A Journal of the ASEAN Committee on Science Technology Vol 30 No. 1&2 2013

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ABOUT THE ASEAN JOURNAL ON SCIENCE AND TECHNOLOGY FOR DEVELOPMENTThe ASEAN Journal on Science and Technology for Development is a refereed Journal of the ASEAN Committeeon Science and Technology (ASEAN COST). It reports on science and technology policies and programmes, andresearch activities undertaken by COST in support of social and economic development of the ASEAN membercountries.The coverage is focused but not limited to, the main areas of activity of ASEAN COST, namely, Biotechnology,Non-Conventional Energy Research, Materials Science and Technology, Marine Sciences, Meteorology andGeophysics, Food Science and Technology, Microelectronics and Information Technology, Space Applications,and Science and Technology Policy, Infrastructure and Resources Development. ABOUT THE ASEAN COMMITTEE ON SCIENCE AND TECHNOLOGYThe ASEAN Committee on Science and Technology was established to strengthen and enhance the capability ofASEAN in science and technology so that it can promote economic development and help achieve a high qualityof life for its people. Its terms and reference are: ●● To generate and promote development of scientific and technological expertise and manpower in the ASEAN region; ●● To facilite and accelerate the transfer of scientific and technological development among ASEAN countries and from more advanced regions of the world to the ASEAN region; ●● To provide support and assistance in the development and application of research discoveries and technological practices of endogenous origin for the common good, and in the more effective use of natural resources available in the ASEAN region and in general; and ●● To provide scientific and technological support towards the implementation of existing and future ASEAN projects.Information on the activities of ASEAN COST can be obtained at its website http://www.asnet.org DISCLAIMERWhile every effort is made to see that no inaccurate or misleading data, opinion or statement appears in the Journal,articles and advertisements in the Journal are the sole responsibility of the contributor or advertiser concerned. Theydo not necessarily represent the views of the Editors, the Editorial Board nor the Editorial Advisory Committee.The Editors, the Editorial Board and the Editorial Advisory Committee and their respective employees, officersand agents accept no responsibility or liability whatsoever for the consequences of any inaccurate or misleadingdata, opinion or statement. © Copyright 2013: ASEAN Committee on Science and TechnologyNo part of this publication may be reproduced, stored in a retrieval system or transmitted in any form of by any means, without permission in writing from the copyright holder.

Editorial Board Editor-in-Chief Emeritus Prof Md Ikram Mohd Said School of Chemical Sciences and Food Technology,Faculty of Science and Technology, Universiti Kebangsaan MalaysiaEditorial Board MembersMalaysia Assoc. Prof Tan Tin WeeDr Ahmad Ibrahim Department of Biochemistry,Chief Executive Officer, National University of SingaporeAcademy of Sciences Malaysia ThailandProf Abdul Halim Shaari Prof Narongrit SombatsompopFaculty of Science, Universiti Putra Malaysia School of Energy, Environment and Materials, King Mongkut’s University of Technology,Prof Thong Kwai Lin ThonburiInstitute of Biological Science, Faculty ofScience/UMBIO Cluster, Institute of Graduate Prof Prida WibulswasStudies, University of Malaya President, Shinawatra UniversityAssoc. Prof Mohd Fadzil Mohd Idris CambodiaHigher Education Leadership Academy, Pal DesMalaysia Vice-Rector, Royal University of Phnom PenhBrunei Darussalam IndonesiaRosita Abdullah Dr Warsito Purwo TarunoSenior Special Duties Officer, Minister, Special Advisor for Research andMinistry of Development CooperationAssoc. Prof Zohrah Sulaiman Lao PDRDeputy Vice-Chancellor, Kongsaysy PhommaxayUniversiti Brunei Darussalam Acting Director General, Cabinet Office of the Ministry of ScienceMyanmar and TechnologyDr Zaw Min AungDirector General, Department of Technical and Keonakhone SaysulianeVocational Education, Acting Director General,Ministry of Science and Technology Department of Information TechnologyPhilippines VietnamDr Carol M. Yorobe Dr Mai HaUndersecretary for Regional Operations, Director General,Department of Science and Technology Ministry of Science and TechnologySingaporeAssoc. Prof Ong Sim HengDepartment of Electrical and ComputerEngineering, National University of Singapore

Editorial Advisory PanelBrunei Darussalam Lao PDREddie Sunny Dr Maydom ChanthanasinhDeputy Permanent Secretary, Deputy Minister, Ministry of Science andMinistry of Development Technology, National COST ChairmanMyanmar SingaporeDr Ko Ko Oo Prof Low Teck SengNational COST Chairman, National COST Chairman,Deputy Minister, Ministry of Science and Managing Director, Agency for Science,Technology Technology and ResearchCambodia ThailandDr Om Romny Assoc. Prof Weerapong PairsuwanDirector, Institute of Technology of Cambodia Deputy Permanent Secretary, Ministry of Science and TechnologyPhilippinesDr Graciano P. Yumul MalaysiaUndersecretary for R&D, Dr Madinah MohamadDepartment of Science and Technology National COST Chairman, Secretary General, Ministry of Science,Indonesia Technology and InnovationProf Syamsa Ardisasmita, DEADeputy Minister for Science and Technology VietnamNetwork, National COST Chairman Dr Le Dinh Tien Deputy Minister for Science and Technology, National COST ChairmanEditor/Technical Editor/Executive Editor Kanesan Solomalai Academy of Sciences Malaysia Dr Mohaida Mohin Higher Education Leadership Academy, Malaysia Production Manager Kamariah Mohd Saidin Universiti Putra Malaysia Publisher Universiti Putra Malaysia Press

Contents ASEAN J. Sc. Technol. Dev. Volume 30(1&2), 2013Computational Fluid Dynamics Simulations of Gas-liquid Two-phase Flow 1Characteristics through a Vertical to Horizontal Right Angled Elbow 17 22 N. Z. Aung and T. Yuwono 29 37Performance Appraisal of Non-governmental Organizations: A Discussion onPakistan 2010 Floods Response and Recovery 44 A. Ali, N. Baig and A. Khan 50 63Toughening of Bisphenol-A Diglycidyl Ether-based Epoxy by Modification withHydroxyl-terminated Liquid Natural Rubber H. L. Pham, B. T. Do, T. S. Pham and D. G. LeSynthesis and Characterisation of Hydroxyl-terminated Liquid Natural Rubberby Photo-Fenton Reaction H. L. Pham, B. T. Do, T. S. Pham and D. G. LePhysical Fitness and Metabolic Profile among Malay Undergraduates of a PublicUniversity in Selangor Malaysia M. Emad, M. Kandiah, W. K. Lim, M. Y. Barakatun-Nisak, A. Rahmat, S. Norasruddin and M. AppukuttyA Preliminary Study: Comparative Toxicity of Extracts from Tinosporatuberculata Beumee and Lumnitzera racemosa Willd on Aedes aegypti LinnaeusLarvae (Diptera: Culicidae) A. A. Wahizatul and R. ShasitaBiodegradation of NR Latex-based Materials via a Carbon Dioxide EvolutionMethod F. M. S. Shabinah and M. Y. A. HashimEffects of Chocolates Using Low Calorie Cocoa Butter Substitutes on Rat’s PlasmaProfile and Determination of Sn-1,3 Position B. Ros-Haniza and S. Mamot



ASEAN J. Sci. Technol. Dev.,  30(1&2): 1 – 16 Computational Fluid Dynamics Simulations ofGas-liquid Two-phase Flow Characteristics through a Vertical to Horizontal Right Angled Elbow N. Z. AUNG1* AND T. YUWONO2Having a clear understanding on the phase distribution of gas-liquid two-phase flow through elbowbends is vital in mixing and separation system designs. This paper presents the computational fluiddynamics (CFD) simulations and experimental observations of gas-liquid two-phase flow patterncharacteristic through a vertical to horizontal right angled (90°) elbow. Experimental observationswere conducted in a transparent test section that consisted of a vertical pipe, elbow bend andhorizontal pipe with an inside diameter of 0.036 m. The CFD simulations were performed by usinga computer software package, FLUENT 6.2. Bubbly flow conditions were created in the vertical testsection with the variation of superficial liquid Reynolds number from 13 497 to 49 488 and volumetricgas quality from 0.05 to 0.2. The CFD results showed a good agreement with experimental results inthe following observations. The results showed that gas-liquid flow pattern inside and downstreamof the elbow bend mainly depended on liquid velocity and it is also influenced by gas quality at highliquid velocities. At lower liquid velocities, gas-liquid separation began early in the elbow bend andgas-phase migrated to outer bend. Then, it smoothly transformed to stratified flow at elbow outlet.When the liquid velocity was further increased, the liquid phase occupied the outer bend rubbingthe gas phase to the inner bend and delayed the formation of gas layer in the horizontal pipe. Theincrease of gas quality in higher liquid velocities promoted gas core formation at the elbow exit andcaused wavy gas layers at the downstream of the elbow.Key words: Gas-liquid; two-phase; flow pattern characteristic; vertical to horizontal; 90° elbowThe understanding of transport phenomena in multi-phase flow piping system designs, sincemultiphase flows plays a vital role in improving these can give strongly interference in phasethe performance of operating systems in distribution and consequently promote theboiling and condensing processes, hydrocarbon vibration of the system (Abdulkadir et al. 2001)production and refining, minerals transport Hence, increasingly, attempts are being madeas well as power generation. Such transport to observe the effect of pipe bends (especiallyphenomena are quite sensitive to the phase 90° elbows) on phase distribution and otherdistribution in the flow termed as ‘flow pattern’. flow related characteristics in multiphase flows.In turn, the flow pattern also mainly dependson the flow velocity and physical properties Akilli (2001) conducted experimentalof each phase and pipe geometry (Akilli et measurements and CFD simulations of gas-al. 2001) In the case of pipe geometry, the solid concentration and velocity profile incorrect usage of pipe bends is very critical in horizontal pipe after vertical-to-horizontal 90°1 Department of Mechanical Engineering, Mandalay Technology University, Myanmar2 Laboratory of Fluid Mechanics, Department of Mechanical Engineering, Institute Technology Sepuluh Nopember, Campus ITS, Sukolilo, Surabaya* Corresponding author (e-mail: [email protected]; [email protected])

ASEAN Journal on Science and Technology for Development, 30(1&2), 2013elbow bend. His distinct observation was that a Zhang et al. (2012) performed CFDstrong rope was formed in the elbow bend and simulations to observe erosive ware damagesit disintegrated within 10D of the pipe after (puncture point locations) in elbow bends byelbow exit. Huseyin (2004) has also performed varying slurry velocity, bend orientation andinvestigations on gas–solid flow characteristics bend angle. They discovered that the locationafter a 90° vertical-to-horizontal elbow. of the maximum erosive location moved to downstream (elbow exit) when slurry velocity Yang and Kuan (2006) have measured increased. Liu et al. (2012) also experimentallythe velocity fluctuation level of gas-solid flow studied air-water flow induced fluctuating forceinside a 90° elbow by using Laser Doppler on a 90° elbow. They discussed force fluctuationAnemometer (LDA). They found that the phenomenon matching with the observations oflevel of velocity fluctuations in the solid flow pattern such as bubbly flow, slug flow andphase was higher than that of the gas phase churn flow. For forgoing review, a summary ofat the bend entrance because of particle-wall information of previous researches that focusedcollisions. Kim et al. (2007) investigated the on 90° elbow bend is shown in Table 1.effect of 90° elbow on local void fractiondistribution. According to their results, From the entire review, it is very obviousthe elbow had more significant effect on that multiphase flow phenomena before, insidephase distribution at further downstream and after elbow bend are very violent and the(L/D = 43.9 after elbow) than immediate effects are undesirable. However, the existencedownstream (L/D = 18.1 after elbow). At of bended pipes is very common in conveyingthe same time, Spedding and Benard (2007) process of oil and gas mixture from downhole toperformed pressured drop measurements separator because they are absolutely necessarythrough a vertical to horizontal 90° elbow for flow directional changes. Thus, in designingbend. They proposed a general correlation for such bended pipes, a clear understanding ofprediction of gas-liquid two-phase pressure phase distribution (or flow pattern) before,drop for elbow bends. The same authors (2008) inside and after the bend is very critical sincealso reported the pressure drop characteristics these can negatively affect the performance ofof water-oil-air three-phase flow through operating system.a vertical to horizontal 90° elbow bend.Concerning the air-water two-phase flow However, available information in literaturepressure drop in vertical to horizontal internal is mostly based on probe measurement.wavy 90° elbow bends, Benbella et al. Indeed, experiences in visual observations(2009) carried out a research. Their results of multiphase flow phenomena without anydemonstrated that wavy 90° wavy elbows intrusive measuring tool are still lack andhad total pressure about 2−5 times greater needed to obtain a better understanding on thethan smooth bends. In the work of Abdulkadir phase distribution through bended pipes. Evenet al. (2011), the effect of 90° bends on air-oil though some visual observations can be found(silicon) flow pattern were observed using in Abdulkadir (2011), the focus point was onlyadvanced instruments such as Electrical inside the elbow bend. Without having visualCapacitance Tomography (ECT), Wire Mesh information at the downstream of the elbowSensor Tomography (WMS) and high-speed bend, a sharp imagination still cannot be madevideo. Changing the flow velocities, they had in designing a bend pipe. Moreover, longdiscovered transitions of flow pattern before elbow bends are also becoming attractive inand after elbow bends. They concluded that industrial applications and related informationhorizontal bend has less effect on the flow is in demand.patterns compared with the vertical bend. 2

N. Z. Aung & T. Yuwono: Gas-liquid Two-phase Flow—through a Vertical to Horizontal 90° ElbowTable 1. Summary of previous researches that focused on effect of elbow.Research (Reference no.) Multiple-phase Elbow geometry MethodologyHuseyin et al. 2004 classification Experiment, CFDKim et al. 2007 R/D = 1.5,3 (vertical toLiu at al. 2012 Gas-solid horizontal upward flow) simulationMahvash & Ross 2008 (Two-phase) ExperimentMahmoud et al. 2012 R/D = 1.5,3 (vertical toMargot et al. 2012 Gas-solid horizontal upward flow) ExperimentRiverina et al. 2006 (Two-phase)Singhal et al. 2002 R/D = 1.5 (horizontal to vertical ExperimentSpedding & Benard 2007 Gas-solid upward flowSpedding et al. 2008 (Two-phase) Experiment R/D = 1.515 (horizontal to Gas-liquid horizontal, the same plane flow) Experiment (Two-phase) R/D = 0.654 (vertical to Experiment and Gas-liquid horizontal upward flow correlations (Two-phase) R/D = 0.654 (vertical to Experiment Gas-liquid-liquid horizontal upward flow (Three-phase) CFD simulation R/D = 4,6,8,10 (vertical to Gas-liquid horizontal upward flow Experiment (Two-phase) R/D = 2.3 (vertical to Gas-liquid horizontal upward flow) (Two-phase) R/D = 3.255 (various Gas-solid orientations) (Two-phase) R/D = 1.451 (vertical to Gas-liquid horizontal upward flow) (Two-phase) In this regard, the aim of this work is to Governing Equationsexperimentally and numerically observe phasedistribution (the flow pattern) characteristic of Flow governing equations for a two-phasegas-liquid two-phase bubbly flow through a mixture are obtained from the ensemblevertical to horizontal right angled (90°) long averaging of the Navier–Stokes equations andelbow bend with a wide focusing view and to the following mass and momentum continuityprovide more descriptive information. equations are solved in computation. Numerical Simulation Continuity equation:Advanced computational methods in fluid 2^tmh + d: ^tm uvmh = 0 (1)dynamics are becoming powerful and 2tcapable of modeling multiphase flows andthe acceptable simulated results are at proven Momentum transfer equation:stage in many researches (Akilli 2001;Zhang 2012; Singhal 2002). Thus, the CFD 2^tm fh + d: ^t uvm uvmh =simulations of gas-liquid two-phase flow 2tthrough a vertical to horizontal elbow bend mare also performed to confirm the experimentalobservations in this work. - dp + d: 6nm ^duvm + uvmT h@ + tm gv + /Fv + d: c n ak tk uvdr,k uvdr,km (2) k=1 3

ASEAN Journal on Science and Technology for Development, 30(1&2), 2013where, the subscript m, k, dr describe the The mesh has 240 000 hexahedral elements. The base of vertical pipe is set as velocity inletmixture, secondary phase and drift respectively, condition and the end of horizontal as outflow µ is viscosity, uv is condition. No slip condition is considered atρveilsocditeyn, spitiys,ptreisssutirme,eF,v is body force vector, the walls.α is volume fraction. For having reasonable accuracy (Singhal Solving Strategies2002; Margot 2002; Mahmoud 2012) thestandard k-ε model is adopted to solve the set A commercial CFD package FLUENT 6.2 isof turbulent kinetic energy and dissipation rate used to solve the set of governing equations;equations. The equations for mixture turbulent continuity, momentum, and turbulent k-εkinetic energy and its dissipation rate are equations. Velocities of phases and gas phaseobtained by the summation of mixture as a fraction are set as known inlet boundarysingle phase. condition for every run. The SIMPLEC algorithm is used for coupling betweenTurbulent kinetic energy equation: velocity and pressure. The second-order upwind discretization scheme is used for the2^tm k h + d: ^tm uvm k h = d: c nt,m dk m + momentum equations while first-order upwind 2t vk discretization is used for volume fraction and (3) k-ε equations. The convergence criteria are Gk,m - tm f third order residual value of each parameter and deviation of 10–5 between the inlet and outletTurbulent dissipation equation: mass flow rates to satisfy the continuity law.2^tm fh + d: ^tm uvm fh = d: c nt,m df m + Experimental Setup 2t vk and Procedure (4)f The schematic diagram of constructed air-waterk ^C1f G k, m - C 2f tm fh two-phase flow loop is shown in Figure 1. The test section consists of 2.1 m long vertical pipe, The turbulent viscosity of the mixture was elbow bend and a horizontal pipe that runs 1 mcalculated by: after the elbow exit. The vertical and horizontal pipes are acrylic pipes which have inside nt,m = Cntm k2 (5) diameter of 0.036 m. The elbow bend is also ! made of acrylic material and has the same inside diameter. The detail structure of the elbow bendwhere the subscript t represents for turbulent, is shown in Figure 2. Aiming to create bubblyk is turbulent kinetic energy, ε is turbulent flow in vertical test section, the air is injecteddissipation rate, C1ε, C2ε, Cµ, σk and σε are the at the base of vertical test section by usingstandard k–ε model constants and G is the radial injectors. There are 32 ports of 710 µmturbulence production term. This standard diameter along the periphery of the injector. Themodel is used without any further modifications liquid flow rate is measured by using “Doppler”taking C1ε =1.44, C2ε =1.92, Cµ =0.09, σk =1 flow meter and the gas flow rate is measuredand σε =1.3 since they have been accepted in by using float type (Dwyer Rate-Master) gasa wide range of wall-bounded air and water flow meter. Two high speed digital cameras areturbulent flows. used to capture the visual observation of flow patterns in vertical pipe, inside elbow bend andComputational Domain at its downstream. Experiments are conductedThe whole test section is considered as thecomputational domain and constructed inGAMBIT 2.2. It is shown in Figure 3a–3b. 4

N. Z. Aung & T. Yuwono: Gas-liquid Two-phase Flow—through a Vertical to Horizontal 90° Elbow1. Water tank 6. Annular air injector 11. Digital camera 12. Pump 7. Pressure gauge 12. Photo editing system 13. Regulation system (Bypass) 8. Thermocouple 13. Test section4. Accumulator 9. Rotameter 14. Digital camera 25. Doppler flow meter 10. Compressor 15. Photo editing system 2 16. Gas-liquid separatorFigure 1. Schematic diagram of experimental test loop. Curvature radius, R = 0.09 m Inside diameter, ID = 0.036 m Outside diameter, ID = 0.04 mFigure 2. Detail structure of elbow bend. 5

ASEAN Journal on Science and Technology for Development, 30(1&2), 2013(a) (b) Figure 3. Computational grid structure of test section: (a) Side view (x-y plane) (b) Cross-sectional view (x-z plane and y-z plane).by varying superficial liquid velocity and Clustered bubbly flow. This kind of flowvolumetric gas quality. The liquid superficial occurs at high superficial liquid velocitiesvelocity (in terms of Reynolds number) is (ReSL = 40490, ReSL = 49488) with lowvaried in the range of ReSL=13497 to 49488 volumetric gas qualities (β = 0.05, β = 0.07) asand the gas volumetric quality (β) is varied in shown in Figure 4a. The gas phase (bubbles)the range of 0.05−0.2. These initial parameters are cluttered in liquid medium forming bubble-are calculated from measureable parameters by clusters. In other word, the bubble distributionusing equations expressed in Appendix. is not symmetric to the vertical axis of the pipe at any elevation and a series of bubble-clusters RESULTS AND DISCUSSION is formed along the pipe.Flow Pattern in Vertical Test Section Homogeneous bubbly flow. This flow condition is observed at every flow conditionIn this work, for all flow conditions, bubbly with medium range of volumetric gas qualitiesflow regimes are created in the vertical test (β = 0.09−0.13) as shown in Figure 4b. Thesection at the upstream of elbow bend. The bubble size becomes larger and it seems thatvisual observations of bubbly flow are captured the bubbles occupy homogeneously over thewith a high speed digital camera at a height of entire cross-section of the pipe at any elevation.0.35 m above the air injector. Some sampleobservations of the bubbly flows in vertical Dense bubbly flow. Figure 4c shows densetest section are shown in Figures 4a–4c. The bubbly flow condition. It is clear that this kindobserved bubbly flows can be classified into of bubbly flow occurs at high gas qualities.three categories. 6

N. Z. Aung & T. Yuwono: Gas-liquid Two-phase Flow—through a Vertical to Horizontal 90° Elbow (a) (b) (c)Figure 4. Visual observations of bubbly flow in vertical test section: (a) ReSL = 49488; β = 0.05; (b) ReSL = 31492; β = 0.11; (c) ReSL= 40490; β =0.2.The entire cross sectional area of the pipe is pressure at the outer surface of the elbow andfilled with bubbles, but formation of elongated the bubbles try to migrate to the outer surface.bubbles is not yet observed. Then, gas-liquid stratification begins before the exit of the elbow bend. Further increaseFlow Pattern in Elbow Bend and of liquid velocity (ReSL = 31492) delays theDownstream gas phase separation from inner surface of elbow bend showing uniformly distribution inFigures 5–9 show the experimental observations the elbow bend. At the outlet of elbow bend,and numerically simulated results of gas-liquid the gas phase moves up to upper surface oftwo-phase flow patterns through the elbow bend horizontal pipe. Formation of gas layer initiatesfor flow conditions of ReSL = 13497−49488 about 2D−3D after elbow exit. Figures 8−9with constant volumetric gas quality β = 0.2. depict comparisons of recorded and computedThe numerical results are taken from both results for flow conditions of ReSL = 40490 andlongitudinal mid-plane and transverse cross- ReSL = 49488 with constant gas quality. Insectional plane at various distances inside and contrast to the former observations, the gasafter elbow bend. The experimental results phase leaves away from the outer surface ofclearly state that the two-phase flow pattern is the elbow and totally concentrates on innermainly governed by liquid velocity. For flow bend. The whole outer surface of the elbowconditions with low liquid velocities (Figures bend is free from migration of gas bubbles and5−6), the gas phase starts to separate from the entire inner surface is apparently coveredinner wall about bend angle (Θ) of 30°−45° by gas layer. This phenomenon is related to theand flows up to the outer wall. It can be increasing of pressure at the outer bend. Whenexplained that the momentum and buoyancy the mixture enters into the elbow bend withforce attained by bubbles overcomes the a high velocity, the liquid phase with higher 7

(a) (b)Figure 5 (a)–(b). Experimental and numerical observation of two-phase flow pattern through elbow bend at ReSL = 13497, β =0.2. 8

(a) (b)Figure 6 (a)–(b). Experimental and numerical observation of two-phase flow pattern through elbow bend at ReSL = 22494, β =0.2. 9

(a) (b)Figure 7 (a)–(b). Experimental and numerical observation of two-phase flow pattern through elbow bend at ReSL = 31492, β =0.2. 10

(a) (b)Figure 8 (a)–(b). Experimental and numerical observation of two-phase flow pattern through elbow bend at ReSL = 40490, β =0.2. 11

(a) (b)Figure 9 (a–b). Experimental and numerical observation of two-phase flow pattern through elbow bend at ReSL = 49488, β =0.2. 12

(a)(b)(c)(d)(e) Figure 10(a)–(e). Experimental and numerical observation of two-phase flow pattern through elbow bend at: (a) ReSL = 13497, β = 0.11; (b) ReSL = 13497, β = 0.15; (c) ReSL = 22494, β = 0.11; (d) ReSL = 22494, β = 0.15; (e) ReSL = 31493, β = 0.11. 13

(f)(g)(h)(i)(j) Figure 10(f)–(j). Experimental and numerical observation of two-phase flow pattern through elbow bend at: (f) ReSL = 31492, β = 0.15; (g) ReSL = 40490, β = 0.11; (h) ReSL = 40490, β = 0.15; (i) ReSL = 49488, β = 0.11; (j) ReSL = 49488, β = 0.15. 14

N. Z. Aung & T. Yuwono: Gas-liquid Two-phase Flow—through a Vertical to Horizontal 90° Elbowmomentum impinges the outer surface and compared with experimental results. Theincreases the surface pressure by pushing the constructed test section diameter was 0.036gas phase to the lower pressure region. However m and the elbow curvature to diameter rationo coalescence of bubbles is found at the inner (R/D) was 2.5. Different flow conditions weresurface since centrifugal force accelerates the created by varying superficial liquid velocitygas bubbles without giving a chance to merge and gas quality.each other. From numerical results (Figures8(b)−9(b)), it is clearly seen that the formation The experimental and numerical resultsof low pressure region at the inner bend creates from this work were of good agreement. Thesetransverse flow (or secondary flow) from elbow results provided a clear view and understandingexit to about 1D. Therefore the bubbles cannot of phase interaction and distribution phenomenamove up to the upper surface of horizontal pipe before, inside and after long elbow bend. Baseduntil a far distance after the elbow outlet. The on recorded observations, it could be concludedbubbly flow is maintained until 5D to 6D after that phase distribution inside and after elbowthe elbow exit. Then, it starts to develop gas- bend mainly depended on liquid velocity. Atliquid stratified flow pattern in horizontal pipe. lower liquid velocities, the gas bubbles migrateIt can be understood that elbow bend causes at the upper surface of bend and smoothlyliquid velocity-dependent interference in flow changed to gas layer at the elbow exit. Whenpattern transition from vertical to horizontal. the liquid velocity was further increased, it occupied the outer surface, suppressed the gas Observed gas-liquid two-phase phenomena phase to inner region of the bend and delayedthrough elbow bend with the variation of the formation of stratified flow pattern. Thegas quality are described in Figures 10. For increase of gas quality in a high liquid velocitylower constant liquid velocities (Figures also caused wavy gas layer after the elbow bend.10(a)−10(d)), the increase of gas velocityenhances the gas layer formation near the ACKNOWLEDGEMENTelbow exit. However, the increase of gasquality promotes the interference at high liquid The authors would to express their special thankvelocities forming a gas core in horizontal to all members of Fluid Mechanic Lab, Mesin,pipe (Figure 10(g)−10(j)). It postpones the ITS for support of their facility and great help.formation of stratified flow pattern and createswavy gas layer at downstream. Therefore, it Appendix 1can be concluded that the phase distributionafter elbow bend also relates to gas quality in Superficial liquid velocity, USL = QL (6)the mixture. A (7) (8) CONCLUSION Superficial gas velocity, USG = QG A (9)Designing a suitable elbow bend is a criticalissue in separation and mixing processes. Since Volumetric quality, b = Q QG (10)long elbow bends are becoming attractive L+Qin such applications, phase distribution (the Lflow pattern) characteristic of gas-liquidtwo-phase bubbly flow through a vertical to Superficial liquid Reynolds number,horizontal right angled (90°) long elbow bendis experimentally observed. Then numerical ReSL = tL U SL D simulations are also performed by using CFD n Lsoftware, FLUENT 6.2 and qualitatively Superficial gas Reynolds number, ReSG = tG UnGSG D 15

ASEAN Journal on Science and Technology for Development, 30(1&2), 2013where, the subscripts G, L, SG, SL denotes Mahmoud, H, Kriaa, W, Mhiri, H, et al. 2012,gas, liquid, superficial gas, superficial liquid ‘Numerical analysis of recirculation bubble sizesrespectively, U is superficial velocity, Q is flow of turbulent co-flowing jet’, J. Eng AppL Comprate, Re is Reynolds number, D is pipe diameter. Fluid, vol. 1, pp. 58–73. Date of submission: January 2013 Mahvash, A & Ross A 2008, ‘Two-phase flow pattern identification using continuous hidden Date of acceptance: March 2014 Markov model’, J. Multiphase Flow. vol. 34, pp. 303–311. REFERENCES Margot, X, Hoyas, S, Gil, A, et al. 2012, ‘NumericalAbdulkadir, M, Zhao, D, Sharaf et al. 2011, modeling of cavitation: validation and paramtetric ‘Interrogating the effect of 90° bends on air– studies’, J. Eng AppL Comp Fluid, vol. 1, pp. silicone oil flows using advanced instrumentation’, 15–24. J. Chem. Eng. Sci., vol. 66, pp. 2453–2467. Riverina, JR, Langre, Ed & Pettigrew, MJ 2006,Akilli, H, Levy, EK & Sahin B 2001, ‘Gas-solid flow ‘Fluctuating forces caused by internal two-phase behavior in a horizontal pipe after a 90° vertical- flow on bends and tees’, J. Sound. Vib., vol. 298, to-horizontal elbow’, J. Powder Technol, vol. pp. 1088–1098. 116, pp. 43–52. Singhal, NH, Athavale, AK & Li, M et al.Benbella S, Al-Shannag M & Al-Anber, ZA 2009, ‘Mathematical basis and validation of the full ‘Gas-liquid pressure drop in vertical internally cavitation model’, J. Fluids Eng 2002, vol. 124, wavy 90° bend’, J. Exp. Therm Fluid Sci., pp. 1–8. vol. 33, pp. 340–347. Spedding PL & Benard E 2007, ‘Gas–liquid twoHuseyin, H, Levy, EK & Besir B 2004, ‘Investigation phase flow through a vertical 90° elbow bend’, of gas–solid flow structure after a 90° vertical- J. Exp. Therm Fluid Sci., vol. 31, pp. 761–769. to-horizontal elbow for low conveying gas velocities’, J. Adv. Powder Technol., vol. 16, Spedding PL, Benard E & Crawford NM 2008, 261–274. ‘Fluid flow through a vertical to horizontal 90° elbow bend III three phase flow’, J. Exp. ThermKim, S, Park, JH, Kojasoy, G et al. 2007, ‘Geometric Fluid Sci., vol. 32, pp. 827–843. effects of 90-degree elbow in the development of interfacial structures in horizontal bubbly flow’, Yang, W & Kuan, B 2006, ‘Experimental J. Nucl. Eng. Des., vol. 237, pp. 2105–2113. investigation of dilute turbulent particulate flow inside a curved 90° bend’, J. Chem. Eng. Sci., vol.Liu, Y, Miwa, S, Hibiki, T et al. 2012, ‘Experimental 61, pp. 359–3601. study of internal two-phase flow induced fluctuating force on a 90° elbow’, J. Chem. Eng. Zhang, H, Tan, Y, Yang & D et al. 2012, ‘Numerical Sci., vol. 76, pp. 173–187. investigation of the location of maximum erosive wear damage in elbow: Effect of slurry velocity, bend orientation and angle of elbow’, J. Powder Technol, vol. 217, pp. 467–476. 16

ASEAN J. Sci. Technol. Dev.,  30(1&2): 17 – 21Performance Appraisal of Non-governmentalOrganizations: A Discussion on Pakistan 2010 Floods Response and Recovery A. ALI1*, N. BAIG1 AND A. KHAN1The paper examines in detail the role of NGOs (Non-governmental Organizations) in response andrecovery phase of a disaster. Donors, INGOs (International Non-governmental Organizations) andNGOs work for the betterment of affected community but due to certain shortfalls, the communitydid not benefit as much as intended. In this research those gray areas are highlighted in detail throughfield visits and interaction with the community devastated by 2010 floods. Lack of inter-agency co-operation, partnership with inexperienced local NGOs and lack of transparency and accountabilitymechanisms are those areas which reduce the effectiveness of response and recovery efforts. Thesegray areas cause loss of precious resources and duplication of efforts which results in increasedvulnerability of that particular community.Key words: Disaster; 2010 flood; response; recovery; non-governmental organizations; internationalnon-governmental organizations; community; inter-agency co-operationIn the last week of July 2010, most of the (Maryum et al. 2012). Electric power supply,Indus River basin in Pakistan submerged due foods and water supply were interrupted byto torrential rains. Resulting floods severely floods in most parts of the country and destroyedaffected about 20 million people and their most of the food stocks like wheat and otherproperty, infrastructure and livelihood along food stuffs across the country and createdwith 1985 deaths and USD9.5 billion economic shortage of these commodities in the affectedloss (Andrew et al. 2010). areas. Livestock and fisheries were destroyed and tube wells were contaminated and clogged Floods has destroyed 728 192 houses with mud carried by flood water.entirely and rendered more than 385 325 housesnon-residential due to rigorous damages. These In district Nowshera of KPK, Nowsheradamages were mostly visible in districts of Kalan is one of the most affected areas in 2010Muzafargarh and Rajenpur in Punjab, Nowshera floods as shown in Figure 1 (Mateeul et al.and Dera Ismail Khan in Khyber-PukhtunKhwa, 2012).and Jafarabad, Jacobabad, Shikaarpur andThatta in Sindh. The provision of critical Nowshera Kalan was totally submerged infacilities like schools and healthcare centres flood water which rendered more than 700 000were severely affected by floods. More than peoples homeless in Nowshera. Dead animals7600 schools were completely destroyed and and dead bodies were lying in the streets, riverneeded to be reconstructed while 436 health and roads and it had a stinging smell in the air.units were either destroyed or severely damaged1 National University of Sciences and Technology, Islamabad, Pakistan* Corresponding author (e-mail: [email protected])

ASEAN Journal on Science and Technology for Development, 30(1&2), 2013Figure 1. District Nowshera, during the 2010 Flood. Such widespread destruction was not others took part in response and recovery of themanageable by the local as well as the national devastated communities (Ali et al. 2012).government and request for external interventionwas made by the Federal Government to tackle INGOsthe situation and reduce further losses. As aresult, Pakistan received overwhelming response Donors Militaryfrom the international community as well asfrom their own people living inside and outside Localfrom the country. Main stakeholders in disaster Communityresponse and recovery were International Non-Governmental Organization (INGOs), Non- Local National/Governmental Organization (NGOs), United NGOs LocalNations, Military, donors, National DisasterManagement Authority (NDMA) / Provincial GovernmentDisaster Management Authority (PDMA),volunteers and charity organizations as shown Figure 2. Different stakeholders of 2010 Flood.in Figure 2. Many INGOs like MedicineSans Frontier (MSF), MuslimAid UK, United The objective of this research is to ascertainNations High Commission for Refugees, that the efforts carried out by NGOs to respondNorwegian Red Cross, International Federation to the emerging situation to build back betterof Red Cross and Red Crescent, Al-Khidmat and resulting social and economic impacts onFoundation, Ummah Welfare Trust, volunteers that community is apprised.from different educational institutions and many 18

A. Ali et al.: Performance Appraisal of NGOs: Discussion on Pakistan 2010 Floods Response and Recovery METHODOLOGY Lack of Inter-agency Co-ordinationThe methodology adopted was extracted from NGOs who take part in disaster responsevarious studies covered by the subject. The main and help victims, have different backgroundssources of primary data were field visits and face and motivation. They are the main source ofto face interviews of the key respondents who providing microfinance and other services butwere either worked as volunteers or affected by according to their own strategies and missionsthe flood and remained present throughout relief (Khan et al. 2009). Due to the strict adherenceand recovery phases. The whole area has been to their own objectives and strategies, they dodivided into urban and rural sub-areas. Urban not co-ordinate with each other and results inarea consists of 14 localities while rural area misuse of scarce and precious resources. Forconsists four villages. Key respondents include example, in the 2010 floods, MSF and UNHCRtwo to four volunteers (male and female) and both have provided Non-Food Items (NFIs) toeight to ten affected households in each urban the same population and resulted in the demandlocality and from each village. Time span for and supply imbalance i.e. NFIs were providedthe primary data collection was 8 months in more than the actual demand.post-disaster scenario. Weekly field visits werearranged each month to collect and record Inexperienced NGOsprimary data. Secondary data were receivedfrom different local and national newspapers Due to the inexperienced NGOs who arein post-disaster scenario for one year and from taking part in disaster response can furtherprogress reports of those organizations who complicate the situation by not co-operatingtook part in response and recovery in the target and co-ordinating with other NGOs and orarea (Adnan et al. 2011, Junqiang et al. 2011). producing poor-quality work. It is evident fromThe information collected from these reports the field visits and respondent views that mostof different NGOs who worked in the target of the NGOs who took part in WATSAN (waterarea on livelihood improvement, rehabilitation/ and sanitation) constructed hand pump on suchreconstruction, WATSAN, WASH (water, points where it was not needed. Those NGOssanitation and hygiene) were compared with who were involved in the recovery phase haveground realities obtained from primary data to provided low quality construction materialsassess the net positive impact of huge public which resulted in bad word of mouth for NGOs.spending by NGOs on affected communitylives. Lack of Community-based Representative Organizations RESULTS AND DISCUSSION Most of the NGOs work with and throughThis research indicates that the work carried local community-based organizations butout by most of the locals NGOs is not upto in developing countries, the influence of asatisfaction of the effected community as it community dictates NGOs which does notis visible from the on-ground realities and represents a community will. The respondentsinteraction with them. The analysis of primary in the target area showed dissatisfaction overdata and different news items and its comparison the behaviour of the staff of NGOs, who werewith reports prepared by different NOGs who acting according to influence by neglecting theworked in the affected areas magnify the needy people (Asif et al. 2013). In the relieffollowing gray areas which contributed to the phase, relief items were distributed throughlow level efficiency and effectiveness of these these influential ones in which they served theirhumanitarian organizations. own nears and dears the most. 19

ASEAN Journal on Science and Technology for Development, 30(1&2), 2013Transparency and Accountability in Delay in Starting of Recovery PhaseRecovery Phase Delay in starting recovery or reconstructionIn the reconstruction phase, design and may result in misuse of resources. Most of theimplementation of reconstruction programmes effected people reconstruct their dwellings asare very important but should be imbed they cannot wait for a long time for aid due towith accountability and transparency. These cultural constraints. After a few months, theseprogrammes must make sure that an effective NGOs do not find houses to reconstruct andcomplaint mechanism is in place for the as a result, the NGOs staff constructs housesneglected people. Interviews with effected for those who does not deserve by acquiringpeople revealed that in the reconstruction monetary benefits.phase, employees of NGOs misused theirpowers and reconstructed houses of those Under-estimating Local Capabilitiespeople who did not deserve just for the sackof few pennies. Due to non-availability of a Under-estimating local capabilities, thecomplaint mechanism, the deserving people behaviour of dependency and misuse ofwere left in the lurch. resources could be the result of an international aid. The background discussion with many Lacking co-ordination and marred by volunteers and locals revealed that manyad-hoc nature, the reconstruction efforts lack NGOs under-estimated the capabilities ofstrategic frame work. People also complained effected people and provided international aidthat in some cases two or three NGOs in such a manner which created the behaviourconstructed houses of a single affected one of dependency and misuse and people becamewhich shows the ad-hoc behaviour and the lazy to work. At last the government removedlack of co-ordination among the responding the shelters provided to the people after flood.agencies. CONCLUSIONINGO’s Partnership with Local NGOs After any disaster, there are too many localINGO’s implement their projects using different NGOs spring out to respond to the emergingstrategies. The most commonly used strategy situation. These local NGOs lack resources andis building partnerships with local NGOs. The expertise to handle such a complex situation.aim through such partnership is, they want to They depend on various donors and INGOs.reach the poorest, neglected and the grass root. Donors and INGOs build partnership to reachBut, the INGOs provide resources to these the most deserving and the gross-root level.local NGOs without accountability and Due to inexperience and lack of resources, thesetransparency as indicated by field visits and local NGOs become the source of problembackground discussion with local people. For and bad reputation for the whole humanitarianexample, the German Society for International community. Misuse of resources and mistrustCooperation provided financial assistance among the affected community could be thethrough the Sarhad Rural Support Program result of depending on these inexperiencedfor WATSAN to each community based NGOs. These problems can be best addressedorganization according to the population but through scrutinizing these local NGOs for theiron ground nothing has been done with the capabilities and past experiences before anysame amount. Just wall chalking and banners partnership is built with them.were prepared by each Community-based-organizations to eye wash the donor and not Date of submission: January 2013more than that (Kristin 2010). Date of acceptance: March 2014 20

A. Ali et al.: Performance Appraisal of NGOs: Discussion on Pakistan 2010 Floods Response and Recovery REFERENCES Junqiang, Xia, Roger, A. Falconer, Lin, B & Tan, G 2011, ‘Numerical assessment of flood hazardAsgary, A, Anjum, MI & Azimi, N 2012, ‘Disaster risk to people and vehicles in flash floods’, recovery and business continuity after the 2010 Environmental Modelling & Software, vol. 26, flood in Pakistan: case of small businesses’, no. 8, pp. 987–998. International Journal of Disaster Risk Reduction, vol. 2, pp. 46–56. Kerr, AC, Khan, M, Mahoney, JJ, Nicholson, KN, Hall, CM 2010, ‘Late Cretaceous alkaline sillsAsif, MK, Haneef, M, Anwar, SK & Tazeem T 2013, of the south Tethyan suture zone, Pakistan: initial ‘Debris-flow hazards on tributary junction fans, melts of the Réunion hotspot?’, Lithos, vol. 117, Chitral, Hindu Kush Range, Northern Pakistan’, no. 1–4, pp. 161–171. Journal of Asian Earth Sciences, vol. 62, pp. 720–733. Khan, MJ, Razzaq, A, Khattak, MK & Garcia, L 2009, ‘Effect of different pre-sowing waterBaqir, M, Sobani, ZA, Bhamani, A, Bham, NS, application depths on wheat yield under spate Sidra Abid, Javeria Farook & Beg, MA 2012, irrigation in Dera Ismael Khan District of ‘Infectious diseases in the aftermath of monsoon Pakistan,’ Agricultural Water Management, vol. flooding in Pakistan’, Asian Pacific Journal of 96, no. 10, pp. 1467–1474. Tropical Biomedicine, vol. 2, no. 1, pp. 76–79. Solberg, K 2010, ‘Worst floods in living memoryHaq, M, Akhtar, M, Muhammad, S, Paras, S & leave Pakistan in paralysis’, The Lancet, vol. 376, Rahmatullah, J 2012, ‘Techniques of Remote no. 9746, pp. 1039–1040. Sensing and GIS for flood monitoring and damage assessment: a case study of Sindh province, Tahir, AA, Chevallier, P, Arnaud, Y, Luc Neppel, L Pakistan’, The Egyptian Journal of Remote & Ahmad, B 2011, ‘Modeling snowmelt-runoff Sensing and Space Science, vol. 15, no. 2, pp. under climate scenarios in the Hunza River basin, 135–141. Karakoram Range, Northern Pakistan’, Journal of Hydrology, vol. 409, no. 1–2, pp. 104–117. 21

ASEAN J. Sci. Technol. Dev.,  30(1&2): 22 – 28Toughening of Bisphenol-A Diglycidyl Ether-basedEpoxy by Modification with Hydroxyl-terminated Liquid Natural Rubber H. L. Pham1*, B. T. Do1, T. S. Pham1 and D. G. Le2Hydroxyl-terminated liquid natural rubbers (HTNRs), prepared by the Photo-Fenton reaction, wereused to modify bisphenol-A diglycidyl ether-based epoxy (DGEBA). A chemical link betweenHTNRs and the epoxy resin was promoted employing toluene diisocyanate. The reactions betweenelastomers and epoxy resin were followed by FTIR. The mechanical properties of the compositeswere evaluated and the microstructure was investigated using scanning electronic microscopy. Theresults showed that the impact resistance of HTNR-modified DGEBA was superior to that of thepure epoxy resin. For the composites with HTNR, the impact resistance increased with elastomerconcentration up to 2.5 parts per hundred parts of resin. Higher concentration of HTNR resulted inlarger particles which gave lower impact values.Key words: Natural rubber; liquid natural rubber; impact resistance; mechanical properties; epoxyresin; SEM; FTIREpoxy resins are one type of thermoset resins their toughness without adverse influence oncombining many attractive features such as their other useful properties i.e. high thermalhigh mechanical properties and excellent stability and low cure shrinkage (Kong et al.dimensional, thermal and environmental 2008; Thomas et al. 2070; Kaynak et al. 2002).stabilities, toughness, rigidity, high temperatureperformance, chemical resistance, adhesive To overcome the above stated disadvantages,properties, formulation latitude and reactivity many types of modifiers were employed towith a wide variety of chemical curing agents, improve the mechanical and thermal propertieshigh mechanical properties and excellent of epoxy resins, such as reactive liquid rubbersdimensional, thermal and environmental (Chikihi et al. 2002; Ratna & Banthia 2007),stabilities. Up till today, epoxy resins are amine-terminated poly(arylene ether ketone)swidely applied as matrix of coatings, adhesives (Yıldız et al. 2027), triblock copolymers (Hydroand composites. However, one practical & Pearson 2007), thermoplastics (Goossensdisadvantage of highly crosslinked materials et al. 2006), carbon nanotubes (Moniruzzamanis it’s poor resistance to crack propagation. et al. 2006) and silicate-based nanofillersThese materials are brittle and cannot be used (Brunner et al. 2006). Modification withfor damage tolerant applications due to the reactive liquid rubbers is one of the mosthigh cross-linking and inherent low toughness effective strategies to toughen epoxy resins.of epoxy resin. So, it is desirable to enhance In this new method, the liquid rubbers were1 Institute of Chemistry, Vietnam Academy of Science and Technology, 18-Hoang Quoc Viet Road, Cau Giay District, Hanoi, Vietnam2 University of Vinh, Nghe An, Vietnam* Corresponding author (e-mail: [email protected])

H.L. Pham et al.: Toughening of Bisphenol by Modification with Hydroxyl-terminated Liquid Natural Rubberinitially dissolved in epoxy resins and then for 3 h before use. The elastomer employed wasthe rubber separated as a discrete particulate a hydroxyl-terminated liquid natural rubberphase due to the decreased solubility of rubber (HTNR) with Mn = 3060 containing hydroxylin matrices, this was caused by the increase groups and having an OH content of 2.2 molof molecular weight of the cross-linked epoxy of OH/mol of HTNR. The toluene diisocyanateresins (Thomas et al. 2000). Many reactive (Fluka AG) employed contained isomers 2,4liquid rubbers, such as acrylate rubber (Kong and 2,6 in 80:20 ratio). Piperidine was chosenet al. 2008), carboxyl-terminated polybutadiene as the curing agent (Aldrich, 98%). Tetra-butyl(CTPB) (Devi & Srivastava 2007), carboxyl- ammonium iodide (TBAI) from BHD Englandterminated butadiene, acrylonitrile copolymer of 98%, was employed as the catalyst for the(CTBN) (Wise et al. 2000) and hydroxyl reaction between the epoxy and the isocyanateterminated polybutadiene (HTPB) (Ozturk groups. Table 1 summarises the experimentalet al. 2001) have been employed as effective conditions used to fabricate these DGEBAtoughening modifiers for epoxy resins. systems.Other high performance polymers have alsobeen used to modify epoxy resins, these Table 1. Composition in parts per hundred of resininclude polysulphone (PSF), poly(etherimide) (phr) for each component in the final materials.(PEI), polyimide (PI) (Mimura et al. 2001),poly(ether ether ketone) (Francis et al. 2005), Materials code ER/ HTNR (phr)polyetesulphone (PES) (Yang et al. 2008),amino-terminatd poly(arylene ether ketone) S0 100: 0(Yıldız et al. 2007). Up to now, there have S1 100: 1.5been no publications regarding the use of liquid S2 100: 2.0natural rubbers (LNRs) in general and HTNRs S3 100: 2.5in particular, to modify epoxy resins. S4 100: 3.0 S5 100: 3.5 The main objective of the present work S6 100: 4.0was to evaluate the use of HTNRs, as impact S7 100: 4.5modifiers for DGEBA. The low reactivity of the S8 100: 6.0hydroxyls of HTNRs toward the epoxy groups S9 100: 8.0imposed the utilization of a route through the S10 100: 10.0use of a bifunctional reagent that would reactwith both groups. The reaction of diisocyates Preparation of the Pre-polymer ofwith hydroxyls is well known in the formation DGEBA-TDI-HTNRof urethane linkages, as in the catalysed reactionof these with epoxy rings. The reactions to chemically modify HTNR and to subsequently link it to the epoxy resin were EXPERIMENTAL conducted in two steps, as shown in Figure 1. First, a reaction between HTNR and TDI wasMaterials carried out to produce urethane links while leaving free isocyanate groups that would reactEpoxy resin (ER), bisphenol-A diglycidyl afterwards with the epoxy groups of DGEBA.ether-based epoxy (DGEBA), DER 331 trade This second reaction was promoted upon thename, from Dow Chemical Company Co. addition of the catalyst and increasing the(USA), with equivalent weight of epoxy groups temperature. At this stage a pre-polymer ofequal to 204.5 g/ equiv, average molar ratio of HTNR and ER was formed in the epoxy resinsecondary hydroxyl groups to epoxy groups medium. This pre-polymer would be furtherequal to 0.355, was dried at 80°C under vacuum diluted before being cured, depending on the final HTNR concentration intended. The TDI 23

ASEAN Journal on Science and Technology for Development, 30(1&2), 2013was employed in excess of the equimolar ratio 5 parts of piperidine were added and then thebetween NCO groups and OH groups in HTNR. mixtures were degassed again. SubsequentlyThis would leave enough isocyanate groups to the mixtures were poured into a pre-heatedreact with epoxy groups. The modification of metal mould and cured in an oven at 120°C forHTNR with TDI was conducted at 120°C for 3 24 h. Specimens for the tests were cut from thish in a nitrogen atmosphere, in the presence of block of cured material.ER. After this period of time, the temperaturewas raised to 160°C, while the catalyst TBAI Characterization of Reaction Productswas added, always in one part per hundred ofER. This condition was kept for another 3 h The reaction products were characterized byand after that the reaction mixture was cooled infrared spectrometry with fourier transformand allowed to rest at room temperature for (FTIR IMPACT 410, Germany) using KBr24 h. Before initialization of the cure process, pellets.the pre-polymer was diluted by the additionof DGEBA and the composites with 1.5, 2.0, Morphological characterization and the2.5, 3.0, 3.5, 4.0, 4.5, 6.0, 8.0 and 10.0 p.h.r. impact behaviour of cured materials wasof HTNR were prepared (S1 to S10 materials then studied. A minimum of 10 specimens oflisted in Table 1). dimensions 63.5 × 12.7 × 10 mm were prepared and tested by the Izod impact method followingCure Process the ISO 180–2000 procedure, in a universal machine for mechanical tests EMIC LTDThe cure process of all materials prepared model 202. For the morphological analysis,followed three steps: the mixture were degassed, specimens were fractured after being cooled (120°C)Figure 1. Scheme showing the formation of functional group urethane in the reaction between hydroxyl groups of HTNR and NCO group of TDI. 24

H.L. Pham et al.: Toughening of Bisphenol by Modification with Hydroxyl-terminated Liquid Natural Rubberin liquid nitrogen in order to prepare a smooth chains was formed, where TDI and HTNRsurface. The analysis was carried out in a were bound through urethane linkages, asscanning electron microscope, JEOL, JSM- illustrated in Figure 1. The FTIR of the product5300 (Japan) using 15 kV working energy and formed in the first step exhibited an absorptiona gold coating. band at 1735 cm–1 (Figure 3b), indicating the formationn of the functional group urethane. RESULTS AND DISCUSSION In the second step, the temperature wasCharacterization of the Pre-polymer of raised to 160°C, the catalyst was added, andDGEBA-(TDI)-HTNR after 3 h the product formed presented the characteristic bands of oxazolidone besides theThe process for the chemical modification of urethane bands, that is a carbonyl absorption atthe DGEBA was carried out through two steps. 1779 cm–1 attributed to a C-N link (Figure 3c).The first involved the reaction of primary OH These FTIR results confirm the formation ofgroups of HTNR with isocyanate groups of the proposed links as shown in scheme 2 ofTDI, by employing an excess of TDI and a Figure 2 but also reveal that DGEBA is linkedreaction temperature of 120°C, in the presence to TDI-HTNR-TDI by the formation of twoof the DGEBA. In this step, a pre-polymer of functional groups, respectively urethane andTDI-HTNR-TDI with isocyanate terminated oxazolidone.(160°C)Figure 2. Scheme showing the formation of functional groups urethane and oxazolidone in the reaction between NCO groups of TDI-HTNR-TDI and epoxy groups of DGEBA. 25

ASEAN Journal on Science and Technology for Development, 30(1&2), 2013Absorbance Wavenumbers (cm–1)Figure 3. FTIR spectrum of HTNR: (a) TDI-HTNR-TDI; and the reaction product between TDI-HTNR- TDI (b) and DGEBA (c).Impact Strength 2.5 phr but it decreased as more elastomer was incorporated. These results allow theThe impact strength results are shown in conclusion that 2.5 phr was the maximumFigure 4. The DGEBA composites were content of HTNR that might be added in ERprepared with different HTNR concentrations. composites for a possitive effect upon theThe impact strength of these materials impact strength.increased with HTNR concentration, up to Impact strength (J/m) HTNR (phr) Figure 4. Impact strength of DGEBA modified with different HTNR concentrations. 26

H.L. Pham et al.: Toughening of Bisphenol by Modification with Hydroxyl-terminated Liquid Natural RubberMicrostructure particles in the epoxy continuous phase, which lead to toughening mechanisms such asThe microstructure of the composites were cavitation of rubber particles followed by voidobserved by the SEM to examine the correlation growth with consequent shear yielding of thebetween particle sizes of the neat elastomeric epoxy matrix (Auad et al. 2001), the higherphase and impact strength results. Figure 5 cavitation resistance of rubber particles mightshows the SEM micrographs of neat DGEBA further improve the toughness of the structure(a), DGEBA modified with 6% of HTNR (b), (Pearson & Yee 1993; Ratna & Banthia 2001).and DGEBA modified with 2.5% of HTNR. The generation of the voids is due to the cavitation of rubber particles, which is the most From these, it could be seen that the important energy-dissipating mechanism in theunmodified ER had only one phase and the case of rubber-toughened epoxy (Pearson &fracture surface was smooth. In the modification Yee 1993; Ratna & Banthia 2001). The reactionwith 2 p.h.r. – 10 p.h.r. of HTNR, a two-phased between NCO groups of TDI-HTNR-TDI andmorphology was seen with the elastomer-rich epoxy groups of DGEBA might lead to anphase forming the continuous matrix and increase in toughness of the epoxy network.the elastomer-rich phase forming dispersedspherical particles, with rubber particles CONCLUSIONuniformly distributed throughout the matrix.The average particle diameters increased Hydroxyl-terminated liquid natural rubbersteadily with HTNR concentration. The data (HTNR) was used to modify bisphenol-Acorrelated with the impact strength results. As diglycidyl ether-based epoxy (DGEBA). AHTNR concentration increased, the impact chemical link between the HTNR and thestrength decreased. All the materials presented epoxy resin was promoted employing toluenephase separation between ER and elastome, diisocyanate. The impact strength results ofwhich was necessary to improve impact DGEBA modified with HTNR were superior toresistance and also showed the excellent those of the pure epoxy resin. Microstructuredispersion of the elastomeric particles in the studies employing SEM, clearly identified theepoxy matrix. two-phase nature of the rubber-modified epoxy, consisting of rubbery particles embedded inToughening Mechanism an epoxy matrix and also showed excellent dispersion of the elastomeric particles inIn the studied material, phase separation the epoxy matrix. HTNR has the potentialgenerated a morphology of spherical HTNR(a) (b) (c)Figure 5. SEMs of the fracture surfaces of (a) neat DGEBA; (b) DGEBA modified with 6% of HTNR; and (c) DGEBA modified with 2.5% of HTNR. 27

ASEAN Journal on Science and Technology for Development, 30(1&2), 2013to be a toughening agent for epoxy resins in Kaynak, C, Ozturk, A & Tincer, T 2002, ‘Flexibilitygeneral and DGEBA in particular, although the improvement of epoxy resin by liquid rubberprocedure used here might impose a limit to the modification’, Polym. Int., vol. 51, pp. 749–756.amount of HTNR that could be incorporated. Kong, J, Tang, Y, Zhang, X & Gu, J 2008, ‘Synergic ACKNOWLEDGEMENT effect of acrylate liquid rubber and bisphenol a on toughness of epoxy resins’, Polym. Bull.,This study was supported by Vietnam’s vol. 60, pp. 229–236.National Foundation for Science andTechnologyDevelopment (NAFOSTED, Mimura, K, Ito, H & Fujioka, H 2001, ‘Toughening104.04.70.09). of epoxy resin modified with in situ polymerized thermoplastic polymers’, Polymer, vol. 42, Date of submission: April 2013 pp. 9223–9233. Date of acceptance: March 2014 Moniruzzaman, M, Du, FM, Romero, N & Winey, KI 2006, ‘Increased flexural modulus and strength REFERENCES in SWNT/epoxy composites by a new fabrication method’, Polymer, vol. 47, no. 1, pp. 293–298.Auad, ML, Frontini, PM, Borrajo, J & Aranguren, MI 2001, ‘Liquid rubber modified vinyl ester resins: Ozturk, A, Kaynak, C & Tincer, T 2001, ‘Effects fracture and mechanical behavior’, Polymer, vol. of liquid rubber modification on the behaviour 42, pp. 3723–3730. of epoxy resin’, Eur. Polym. J., vol. 37, no. 12, pp. 2353–2363.Brunner, AJ, Necola, A, Rees, M, Gasser, P, Kornmann, X, Thomann, R & Barbezat, M 2006, Pearson, RA & Yee, AF 1993, ‘Toughening ‘The influence of silicate-based nano-filler on the mechanisms in thermoplastic-modified epoxies: fracture toughness of epoxy resin’, Eng. Fract. 1. Modification using poly(phenylene oxide)’, Mech., vol. 73, pp. 2336–2345. Polymer, vol. 34, no. 17, pp. 3658–3670.Chikihi, N, Fellahi, S & Baker, M 2002, ‘Modification Ratna, D & Banthia, AK 2007, ‘Reactive acrylic of epoxy resin using reactive liquid (ATBN) liquid rubber with terminal and pendant carboxyl rubber’, Eur. Polym. J., vol. 38, pp. 251–264. groups as a modifier for epoxy resin’, Polym. Eng. Sci., vol. 47, no. 1, pp. 26–33.Devi, A & Srivastava, D 2007, ‘Studies on the blends of cardanol-based epoxidized novolac Ratna, D, Banthia, AK & Deb, PC 2001, ‘Acrylate- type phenolic resin and carboxyl-terminated based liquid rubber as impact modifier for polybutadiene (CTPB)’, I. Mater. Sci. Eng. A, epoxy resin’, J. Appl. Polym. Sci., vol. 80, vol. 458, no. 1–2, pp. 336–347. pp. 1792–1801.Francis, B, Thomas, S, Jose, J, Ramaswamy, R & Thomas, R, Durix, S, Sinturel, C, Omonov, T, Rao, VL 2005, ‘Hydroxyl terminated poly(ether Goossens, S, Groeninckx, G, Moldenaers, P & ether ketone) with pendent methyl group Thomas, S 2007, ‘Cure kinetics, morphology toughened epoxy resin: miscibility, morphology and miscibility of modified DGEBA-based epoxy and mechanical properties’, Polymer, vol. 46, resin – effects of a liquid rubber inclusion’, pp. 12372–12385. Polymer, vol. 48, pp. 1695–1710.Goossens, S, Goderis, B & Groeninckx, G Wise, CW, Cook, WD & Goodwin, AA 2000, 2006, ‘Reaction-induced phase separation in ‘CTBN rubber phase precipitation in model epoxy crystallizable micro- and nanostructured high resins’, Polymer, vol. 41, no. 12, pp. 4625–4633. melting thermoplastic/epoxy resin blends’, Macromol, vol. 39, no. 8, pp. 2953–2963. Yang, G, Zheng, B, Yang, J, Xu, G & Fu, Sh 2008, ‘Preparation and cryogenic mechanical propertiesHydro, RM & Pearson, RA 2007, ‘Epoxy- toughened of epoxy resins modified by poly(ethersulfone)’, with triblock copolymers’, J. Polym. Sci., Part B: J. Polym. Sci. Part A: Polym. Chem., vol. 46, Polym. Phys., vol. 45, pp. 1470–1481. pp. 612–624. Yıldız, E, Ozarslan, O, Kuyulu, A & Güngör, A 2007, ‘Toughening of epoxy resins by amine terminated poly(arylene ether ketone)s having pendant tertiary butyl groups’, Polym. Bull., vol. 58, pp. 503–511. 28

ASEAN J. Sci. Technol. Dev.,  30(1&2): 29 – 36Synthesis and Characterisation of Hydroxyl-terminated Liquid Natural Rubber by Photo-Fenton Reaction H. L. PHAM1*, B. T. DO1, T. S. PHAM1 AND D. G. LE2 Hydroxyl-terminated liquid natural rubber (HTNR) was prepared by the photo-Fenton reaction, which was carried out in solution in the presence of H2O2/Fe(II) combined with UV irradiation. The HTNR obtained was characterized by GPC, FT-IR, 1H-NMR, 13C-NMR, DEPT-NMR spectroscopy as well as by chemical methods. A probable mechanism leading to the formation of HTNR was discussed based on the analytical data. Key words: Synthesis; natural rubber; liquid natural rubber; FT-IR; gel permeation chromatography (GPC); epoxy; UV irradiationBasically, the methods for the preparation liquid natural rubbers (HTNRs) using hydrogenof liquid natural rubbers (LNRs) involve peroxide as the reagent at high temperaturecontrolled degradation or depolymerization and pressure, while Ravindran and co-of the natural rubber (NR) backbone via workers reported the production of HTNRsoxidative chain scissions by either chemical by photochemical depolymerization of NRor photochemical routes. Thus far, several toluene solution at room temperature in themethods leading to the production of LNRs presence of H2O2 and homogenizing agentshave been developed and can be placed into such as methanol and THF (Ravindran et al.three main categories, i.e. redox, photochemical 1988; Nor & Ebdon 1988).degradation and oxidation at high temperatureand pressure. Of these methods, the redox and It is well known that the catalyzation ofphotochemical methods have received the most hydrogen peroxide by ferrous sulfate, Fenton’sattention (Ravindran et al. 1988). reagent, is one of the most common advanced oxidation processes. Fenton’s reaction is defined According to the first method, NR in as the catalytic generation of hydroxyl radicalthe latex stage or in an organic solvent was resulting from the chain reaction betweendegraded on a large scale by the redox reagent ferrous ion and hydrogen peroxide, and organicphenylhydrazine and atmospheric oxygen at compounds could be oxidized according the50°–70°C. The method yielded LNRs with chain reaction mechanism (Kang & Kwangterminal carbonyl groups which in the presence 2000; Zhang et al. 2005). Recent reports indicateof excess phenylhydrazine were transformed that a combination of H2O2/UV irradiation withinto phenylhydrazones (Nor & Ebdon 1988). Fe (II), the so-called the photo-Fenton process,Concerning the photochemical method, can significantly enhance decomposition ofGupta et al. obtained hydroxyl-terminated a variety of organic compounds, including1 Institute of Chemistry, Vietnam Academy of Science and Technology, 18-Hoang Quoc Viet Road, Cau Giay District, Hanoi, Vietnam.2 University of Vinh, Nghean, Vietnam.* Corresponding author (e-mail: [email protected])

ASEAN Journal on Science and Technology for Development, 30(1&2), 2013depolymerization of a variety of polymers, such The pH of the solution was adjusted withas the different copolymers of acrylamide and H2SO4 and /or NaOH solution in THF. Allacrylic acid (Mai et al. 2002), polychloroprene experiments were conducted at pH~2.5–3.0, and(Freitas et al. 2005), aminosilicone polymer the H2O2/ Fe (II) molar ratio was maintained at(Teixeira et al. 2005), NR and polychloroprene/ 1.5 because these values were optimum for theNR blends (Freitas et al. 2008), and PVA (Lei photo-Fenton reaction (Piglatello et al. 1999;et al. 1998; Giroto et al. 2006). Giang 2010). The reaction temperature was varied from 30°C to 70°C using a water bath In this paper, we report some results that for a reaction time period of 1 h to 50 h.concern the preparation of HTNR by thephoto-Fenton reaction, the characterization of For the experiment, a 160 W high pressurethe HTNR obtained by GPC, FTIR, 1H-NMR, Hg lamp was used as a UV light source. The13C-NMR spectroscopy as well as by chemical beam was parallel and the length between themethods. The mechanism of depolymerization lamp and the reactor wall was 3 cm.and hydroxylation of NR to form HTNR basedon the analytical data is also discussed in this After about 32 h of irradiation, 0.2 gstudy. hydroquinone (about 0.02% w/v of the reaction mixture) was dispersed in the solution and that EXPERIMENTAL was allowed to stand for a certain time. A layer of water separated at the bottom along withMaterials some white deposits as by-products. These were removed, and liquefied rubber was recoveredNatural crumb rubber (SVR20, Mn~780,000) from the top toluene layer by distilling off thewas supplied by the Dong Duong Group,Vietnam. solvent under low pressure. The product wasToluene, methanol, and tetrahydrofuran (THF) finally washed successively with water andwere of reagent grade and used as received. methanol, treated with 0.6% w/w SantowhiteHydroquinone ReagentPlus® from Aldrich MK antioxidant and finally vacuum dried.was used. Santowhite MK, the non-staining The sample for analysis was purified furtherantioxidant and phenyl-b-naphthylamine were by repeated precipitation of methanol fromobtained from Merck. FeSO4.7H2O, H2O2 (30%, the toluene solution and dried in a vacuumw/w), H2SO4, were also purchased from Merck. oven. The by-product was finally washed withAll other chemicals and solvents were of purest methanol and dried in a vacuum to obtain agrade commercially available and used without 7%–8% yield of highly viscid material.further purification.Experimental Procedure MeasurementsNatural crumb rubber was masticated for 30 The molecular weights and molecular weightmin at 40°C. 10 g of it was dissolved in 100 distribution of the original NR as well asml of toluene and the solution was charged those of the HTNRs were determined by a gelin a reactor, a flat-bottomed borosilicate glass permeation chromatography (GPC) systemflask of 250 ml capacity fitted with a water equipped with a series of PL aquagel-OHcondenser, a magnetic stirrer and a water bath. columns (one Guard 8 mm, 50 × 7.5 mmPrecise amounts of Fenton reagent (Fe (II) and and two MIXED 8 mm, 300 × 7.5 mm, PLLH2O2) were added dropwise and continuously Laboratories, UK), and a refractive index (RI)stirred with a magnetic bar. The mixture was detector (RI2000-F, SFD, Torrance, CA), usinghomogenized to a certain extent by the addition polystyrene standards of different molecularof 25 ml of THF. weight and narrow polydispersity to produce a 30

H.L. Pham et al.: Synthesis and Characterisation of Hydroxyl-terminated Liquid Natural Rubber by Photo-Fenton Reactioncalibration curve. The mobile phase was 1.0 ml/ RESULTS AND DISCUSSIONmin, and the columns and the RI detector cellwere maintained at 30°C. The molecular weight Characterization of Hydroxyl-terminated(Mn) of the original NR, as determined by the Liquid Natural Rubber (HTNR)above-mentioned methods, was about 780 000.A sample of HTNR having Mn~3060 was used The original natural rubber (NR) and thethroughout this study for characterization by product obtained by the photo-Fenton process,1H-NMR, 13C-NMR, DEPT-NMR and FTIR HTNR, were analyzed by FTIR, 1H-NMR,analyses. This sample of HTNR would also be 13C-NRM, DEPT- NMR, and other chemicalused to modify bisphenol-A diglycidyl eter- methods.based epoxy (DGEBA), the results of whichwere going to be published in the other article The following absorptions were observedin this issue of ASEAN J. Sc. Technol. Dev., in the IR spectra, both of the original NR (Figurepp. 22–28. 1a) and of HTNR (Figure 1b): 3032 cm–1 (m), 2958 cm–1 (s), 2862 cm–1 (s), 2726 cm–1 (s) The 1H-NMR, 13C-NMR and DEPT-NMR (C-H str.); 1661 cm–1 (m, C=C, cis-vinylene);spectra of the investigated samples were 1446 cm-1 (s), 1377 cm–1 (s) (C-H def.); 891 cm–1recorded from a solution in CDCl3 using NMR (m, -CH3 def.); 842 cm–1 (s, C-H out of planespectrometer (NMR-Brucker-500 MHz). FTIR def. in –CHR=CCR1).analysis was performed on a FTIR IMPACT410 spectrometer and the samples were scanned Apart from the major IR absorptionfrom 400 – 4000 cm–1. band characteristics for cis-1,4-polyisoprene (cis-1,4-PIP), other IR absorptions were also Hydroxyl, hydroperoxide, carboxyl, and observed in the FTIR spectrum of HTNRcarbonyl groups were estimated using standard (Figure 1b): a broad absorption band at 3600–methods (Krause et al. 1983). 3400 cm–1, characteristic of OH stretching vibration; an absorption band at 1310 cm–1 (a) (b)Figure 1. FTIR spectrum of (a) NR and (b) HTNR prepared by the photo-Fenton process. 31

ASEAN Journal on Science and Technology for Development, 30(1&2), 2013(m, C-O str., aliph.primary.alcohol) that p.p.m.; C3: d = 125.03 p.p.m.; C4: d = 26.38confirmed the presence of primary hydroxyl p.p.m.; C5: d =23.4 p.p.m. (Equation 10).groups in the depolymerized product, i.e. inthe HTNR. Apart from these major peaks the spectrum also contained minor peaks at d = 78.39, 76.98 The 1H-NMR and 13C-NMR spectra in and 75.57 p.p.m. due to CDCl3. Other minorCDCl3 at 28°C of the depolymerized product peaks at d = 60.847 and 64.540 p.p.m. could(Figures 2a, b and 3a, b) lent further support to be due to a-carbons attached to the hydroxylthe above conclusion.1H-NMR: d = 1.679 p.p.m. groups in structures like (I) and (II), respectively[s; -CH3 (5), 3H]; d =2.042 p.p.m. [brs; -CH2-(1) and hence could indeed correspond to anand -CH2-(4), 4H]; d = 5.125 p.p.m. [m; CH (3), a-hydroxymethyl group. The allylic hydroxyl1H]. The spectrum also contained minor peaks protons in the 1H-NMR spectra were masked byat d from 1.254 ppm to 1.611 p.p.m., indicating the multiples at d = 5.125 p.p.m. of the >C=C-Hthe probable presence of side products. protons (Equation 9). Several minor peaks couldA minor peak was observed at around d ~ 2.69 also be observed at d from 2.00 to 3.53 p.p.m. inppm (Figure 2b) in the 1H-NMR of HTNR the 13C-NMR spectrum of HTNR (Figure 3b),prepared by the photo-Fenton reaction due indicating the probable side products due to theto the formation of an epoxy group, i.e. the formation of epoxy group.proton attached to the oxirane ring (Burfieldet al. 1984), whereas it was not observed in the The broad OH stretching band at 3600 cm–11H-NMR of the original NR (Figure 2a). – 3400 cm–1 in the FTIR spectrum of the HTNR (Figure 1b) and also the peaks at d =60.847 The signal due to the hydroxyl proton in p.p.m. and 64.540 p.p.m. (Figure 3b) which werethe hydroxymethyl group is usually observed characteristic of the a-carbons of allylalcoholaround d = 4.0 p.p.m. to 4.2 p.p.m. This in the 13C-NMR spectrum of HTNR suggesthowever, could not be detected in the present the terminal hydroxyl groups in the product.case, since the signal / noise ratio was too The allylic hydroxyl protons in the 1H-NMRunfavorable to see the end groups. spectra were masked by the multiples at d = 5.125 p.p.m. of the >C=C-H protons. The 13C-NMR spectrum indicated 13Cshieldings, typical of cis-1,4-PIP at the following All the other signal characteristics for bothpositions: C1: d = 32.23 p.p.m.; C2: d = 135.16 NR and HTNR were observed in the 1H-NMR (a) (b)Figure 2. 1H-NMR spectrum of NR(a) and HTNR(b) prepared by the photo-Fenton reaction. 32

H.L. Pham et al.: Synthesis and Characterisation of Hydroxyl-terminated Liquid Natural Rubber by Photo-Fenton Reaction (a) (b)Figure 3. 13C-NMR spectrum of NR (a), and HTNR (b), prepared by the photo-Fenton process.spectrum (Figures 2a, b): d = 5.08 p.p.m., (=CH); d = 2.00 p.p.m., (-CH2-); d = 1.67 p.p.m., (-CH3),as well as in the 13C-NMR spectrum (Figure 3): d = 135.012 p.p.m., (C2 atom); d = 124.900 p.p.m.,(C3 atom); d = 32.216 p.p.m., (C1 atom); d = 26.409 p.p.m., (C4 atom); and d = 23.433 p.p.m.,(C5 atom). The cis-1,4-PIP configuration of both NR and LNRs were preserved in the DEPT-NMRspectrum (Figure 4). The main absorption bands, characteristic of NR, were also preserved in theFTIR spectra. All these indicated that the cis-1,4-PIP configuration was not disturbed during thedepolymerization process. Further evidence was the fact that there was no observed change in theabsorption band of the isoprene unit, i.e. at 836 cm-1 in the FTIR spectrum (Figures 1a, b). The hydroxyl value estimated for HTNR was 27.12 mg of KOH / g, which gave it a hydroxylfunctionality of 1.97–1.98. The product readily reacts with diisocyanates such as toluenediisocyanate, leading to chain extention.Mechanism of Depolymerization of NR by the Photo-Fenton ProcessIt is well known that in the photo-Fenton process, the reaction between H2O2 and ferrous salt, i.e.the Fenton reaction, the primary reactions in representative Fenton process are (Yang et al. 2005).Fe2+ + H2O2 + H+ → Fe3+ + HO● + H2O (k1 = 58 mol–1dm3.s–1) (1)Fe3+ + H2O2 → Fe2+ + H+ + HOO● (k2 = 0.02 mol–1dm3.s–1) (2) As seen from Equations 1 and 2, the decomposition of H2O2 by iron ions is through theinteraction between Fe2+ and Fe3+. As the reaction rate in Equation 1 was faster than that ofEquation 2, Fe2+ was rapidly oxidized to Fe3+ in the reaction process. Therefore, the concentrationof ●OH in the solution rapidly increased and could degrade the NR macromolecule. In addition,from Equation 2 it could be seen that Fe2+ could be re-generated from the reduction of Fe3+, leadingto the continuous generation of ●OH. The combination of thermal process and UV irradiationenabled the oxidation power of Fenton reagent to be significantly increased due mainly to thephoto-reduction of Fe(III) to Fe(II), which could react with H2O2 establishing a cycle mechanismof generating additional ●OH by Equation 3.Fe3+ + H2O2 + hv → Fe2+ + OH● + H+ (3)33

ASEAN Journal on Science and Technology for Development, 30(1&2), 2013 Figure 4. DEPT spectra of HTNR prepared by the photo-Fenton reaction. The hydrogen peroxide used in the degradation process is susceptible to decomposition underthe influence of radiation. Although hydrogen peroxide has an absorption maximum at 254 nm; itinteracts with radiation up to 370 nm, yielding hydroxyl radicals. If hydrogen peroxide and hydroxylradicals were in excess, competitive reactions could take place (Yang et al. 2005). Hydroxyl radicalsare prone to recombination or to reactions according to the following schemes: OH● + H2O2 → HOO● + H2O (k3 = 2.7 × 107 mol–1dm3.s–1) (4) HOO● + H2O2 → OH● + H2O + O2 (k4 = 0.5 ± 0.009 mol–1dm3.s–1) (5) 2HOO● → O2 + H2O2 (k5 = 8.3 × 105 mol–1dm3.s–1) (6) 2HOO● + OH● → O2 + H2O2 (k6 = 1.0 × 1010 mol–1dm3.s–1) (7) 2OH● → H2O2 (k7 = 4.2 × 109 mol–1dm3.s–1) (8) Ravindran and co-workers (1988) have demonstrated the existence of Structures 1 and 2 inthe depolymerized products: 34

H.L. Pham et al.: Synthesis and Characterisation of Hydroxyl-terminated Liquid Natural Rubber by Photo-Fenton Reaction by the photo-Fenton process leading to the formation of HTNR could be suggested to be as below (Structure 4). (I) Structure 1 1,4-cis-polyisoprene (II)Structure 2 The generation of such structural entities Structure 4entails the cleavage of the original rubbermolecule between the a-carbon atoms. In the CONCLUSIONScase of NR, the s bond between a- methylenic Hydroxyl-terminated liquid natural rubbergroups which connect the isoprene units are not (HTNR) was successfully prepared by thein the same plane with the double bonds. This Photo-Fenton reaction, which was carried outis because there is a tendency of coiling up of in solution in the presence of H2O2/ Fe (II)the rubber segments due to its cis configuration combined with UV irradiation. The HTNRs(Structure 3): obtained were characterized by FTIR, 1H-NMR, 13C-NMR and DEPT-NMR spectroscopy as 1,4-cis-polyisoprene well as by chemical methods. A probable Structure 3 mechanism leading to the formation of HTNR was discussed based on the analytical data. The steric hindrance caused by such anunbalanced structure with pendent methyl Acknowledgementgroups weakens the -CH2-CH2- bond, leading This study was supported by the Vietnam’sto its rupture under certain conditions which National Foundation for Science andcould be provided by thermal energy or chain Technology Development (NAFOSTED,modifications caused by radical species or by 104.04.70.09).radiation. Date of submission: January 2014 Based on the above analytical data, themechanism for the depolymerization of NR Date of acceptance: March 2014 35

ASEAN Journal on Science and Technology for Development, 30(1&2), 2013 References Mai, C, Majcherczyk, A, Schormann, W & Huttermann, A 2002, ‘Degradation of acrylicBurfield, DR, Lim, KL, Law, KS & Soon, Ng copolymers by Fenton’s reagent’, Polym. Deg. 1984, ‘Analysis of epoxidized natural rubber. A Stab., vol. 75, pp. 107–112. comparative study of D.S.C., N.M.R., elemental analysis and direct titration methods’, Polymer, Neyens, E & Baeyens, J 2003, ‘A review of clasical vol. 25, pp. 995–998. Fenton’s peroxidation as an advance oxidation technique’, J. Hazard Mater., vol. B98, pp.Freitas, AR, Vidotti, GJ, Rubira, AF & Muniz, EC 33–50. 2005, ‘Polychloroprene degradation by a Photo- Fenton process’, Polym. Deg. Stab., vol. 87, pp. Nor, HM & Ebdon, JR 1998, ‘Telechelic liquid 425–432. natural rubber: a review’, Prog. Polym. Sci., vol. 23, no.1, pp. 143–177.Freitas, AR, Vidotti, GJ, Rubira, AF & Muniz, EC 2008, ‘Degradation of polychloroprene/natural Piglatello, JJ, Liu, D & Huston, P 1999, ‘Evidence rubber (PCP/NR) blends by photo-Fenton for an additional oxidant in the photo-assisted process’, Polym. Deg. Stab., vol. 93, pp. 601–607. Fenton reaction’, Environ. Sci. Technol., vol. 33, pp. 1832–1839.Giang, LD 2010, ‘Modification of epoxy resin with epoxidized liquid natural rubber’ (in Vietnamese), Ravindran, T, Gopinathan, NMR & Francis, JD PhD Thesis, Univesity of Vinh. 1988, ‘Production of hydroxyl-terminated liquid natural rubber-mechanism of photochemicalGiroto, JA, Guardani, R, Teixeira ACSC & depolymerization and hydroxylation’, J. Appl. Nascimento, CAO 2006, ‘Study on the photo- Polym. Sci., vol. 35, no. 5, pp. 1227–1239. Fenton degradation of polyvinyl alcohol in aqueous solution’, Chem. Eng. Proc., vol. 45, Teixeira, ACSC, Guardani, RG, Braun, AM, Oliveros, pp. 523–532. E & Nascimento CAO 2005, ‘Degradation of an aminosilicone polymer in a water emulsion byKang, YW & Kwang, KY 2000, ‘Effect of reaction the Fenton and the photochemically enhanced conditions on the oxidation efficiency in the Fenton reactions, Chem. Eng. Proc., vol. 44, pp. Fenton process’, Water Res., vol. 34, pp. 2786– 923–931. 2790. Zhang, H, Choi, HZ & Huang, CP 2005,Krause, A, Lange, A & Erzin, M 1983, Plastic ‘Optimization of Fenton process for the treatment analysis guide, Macmillan, New York. of landfill leachate’, J. Hazard Mater., vol. B125, pp. 166–174.Lei, L , Hu X, Yue, PL, Bossmann, SH, Glib, S & Braun, AM 1998, ‘Oxidative degradation Yang, GP, Zhao, XK, Sun, XJ & Lu, XL 2005, of polyvinyl alcohol by the photochemically ‘Oxidative degradation of diethyl phthalate by enhanced Fenton reaction’, J. Photochem photochemically-enhanced Fenton reaction’, Photobiol, A : Chemistry, vol. 116, pp. 159–166. J. Hazard Mater., vol. B126, pp. 112–118. 36

ASEAN J. Sci. Technol. Dev.,  30(1&2): 37 – 43Physical Fitness and Metabolic Profile amongMalay Undergraduates of a Public University in Selangor MalaysiaM. EMAD1, M. KANDIAH2, W. K. LIM3, M. Y. BARAKATUN-NISAK1, A. RAHMAT4, S. NORASRUDDIN4 AND M. APPUKUTTY4*This study investigated health-related components of physical fitness consisting of morphologicalfitness (body fat % or BF %; Body Mass Index or BMI; and waist circumference or WC), metabolicfitness (blood glucose, lipid profiles and haemoglobin) and aerobic capacity (VO2max). This cross-sectional study involved 324 undergraduates recruited voluntarily by systematic random samplingfrom a public university in the city Shah Alam, Selangor Malaysia. The respondents’ aerobic capacitywas measured by field fitness tests and anthropometric measurements using standard protocols. Themean BMI of respondents was 22.51 ± 4.18 kg/m2, and majority of the respondents (93%) are withinnormal range of WC. The prevalence of underweight was 13.5% and overweight/obese was 20.2%.The blood glucose levels of respondents were within the normal range (94.4%) and about 5% offemale respondents had moderate anaemia. More than 70% of the males and 25% of the femaleshad poor VO2max levels (aerobic capacity). In summary, the present results suggest the necessityof health promotion programme focusing on physical activity and nutrition for university students.Key words: Anthropometric; aerobic capacity; university students; physical activity; nutritionPhysical inactivity and poor cardiorespiratory World Health Organization (WHO) predictsfitness is strongly associated with an increased that the majority of deaths by broad causerisk of premature disease and death (Lakka (59%) are from non-communicable diseaseset al. 2003). Although the relationship between (NCDs).life-threatening health consequences andphysical inactivity has been clearly established, The current understanding is that PAthe majority of adults continue to lead sedentary and physical fitness are reciprocally relatedlifestyles (Flegal et al. 2002). In the US, and that they exert independent effects onapproximately one-half of university students’ health. Health is also an important factor fordo not meet current physical activity (PA) academic achievement at school (Novello et al.recommendations (Irwin 2004) and one-third 1997) and in higher education (Tsouros et al.are classified as either overweight or obese 1998). The academic achievements of students(American College Health Association 2005). in higher education institutions face dual1 Department of Nutrition and Dietetics, Faculty of Medicine and Health Sciences, University Putra Malaysia, Kuala Lumpur, Malaysia2 Department of Food Science and Nutrition, Faculty of Applied Sciences, UCSI University, Kuala Lumpur, Malaysia3 Department of Community Health, Faculty of Medicine and Health Sciences, University Putra Malaysia, Kuala Lumpur, Malaysia4 Exercise and Sports Nutrition Research Group, Faculty of Sports Science and Recreation, University Technology MARA, Shah Alam, Selangor, Malaysia* Corresponding author (e-mail: [email protected])

ASEAN Journal on Science and Technology for Development, 30(1&2), 2013challenges namely the continuous changes in the n = 50 + 8 m (Cochran 1977), where “m” isdemographic pattern of the student and economy equal to the number of independent variables,(Ansari et al. 2010). Poor school performance the sample size derived was 324 respondents.is associated with health-compromisingbehaviors and physical, mental, and emotional After adding a non-response rate of 20%,problems (Symons & Cinelli 1997). School a total of 390 students were needed for theperformance is also compromised by poor study. A list of first year students was obtainednutrition, substance abuse, sedentarylifestyle, from the assistant registrar of the faculty,violence and depression (Ansari et al. 2010). which showed that there were almost 900Thus, healthy eating and an active lifestyle students on the list. A ‘systematic randommust be incorporated in daily life for better life sampling’ approach was adopted wherebyand it must start from young. Practicing a good every alternate student on the list was selected.health-related fitness is related to lower risk of Later, these students were contacted via emaildisease and improved quality of life. Evidence or telephone, and briefed about the study.suggests that maintenance of a healthy weight Those who had current acute illness such asthroughout the lifespan is a key component for fever and influenza or any chronic disease, hadprotection against non-communicable diseases participated in other research projects, or who(NCDs). were more than 25 years old were excluded from the study. In due course after following The physical fitness among Malaysian the inclusion and exclusion criteria, a total ofuniversity students information is lacking. 324 respondents met the inclusion criteria andThere was a need to identify and evaluate responded to the data collection. Data protectionphysical fitness among university students, and confidentiality were observed at all times.which will be reference data for future health A respondent’s information sheet was attachedintervention studies among university students. to each questionnaire, and respondents wereTherefore, the purpose of the present study was asked to read the information sheet and keepto determine morphological fitness (body fat % it for future reference. Respondents were alsoor BF %; Body Mass Index or BMI; and waist asked to sign a consent form once they agreed tocircumference or WC), metabolic fitness (blood participate in the study. The information on theglucose, lipid profiles and haemoglobin) and respondents’ personal attributes, such as gender,aerobic capacity (VO2max) among a selected age, university entry level (matriculation,public university in Shah Alam Selangor A-level and O-level), place of accommodationMalaysia. (campus or off-campus), allowance sufficiency with a four-point response scale (Ansari et al. MATERIALSAND METHODS 2010) (1 = “always insufficient”, 4 = “always sufficient”) and scholarship (yes or no)Study Design were recorded using the self-administered questionnaire.This was a cross-sectional study undertakenamong first year students at University The respondents’ stature was measuredTechnology MARA (UiTM), Shah Alam using a non-stretchable stadiometer (SECAduring the academic session of the years 2010 201, Germany). Weight was measured by anto 2012. Ethical approval was obtained from the Omron HBF-514C full body compositionEthics Committee of the Faculty of Medicine sensing monitor and scale (OMRON, Japan).and Health Science, University Putra Malaysia The waist circumference (WC) was measured(UPM). According to the sample size formula; 38

M. Emad et al.: Physical Fitness and Metabolic Profile among Malay Undergraduates of a Public Universityusing a non-stretchable measuring tape, and RESULTS AND DISSCUSIONBF% was measured using a bioelectricalimpedance analysis (BIA) technique using the A total of 324 Malay respondents wereOmron HBF-514C (OMRON, Japan). The BMI recruited, the majority of whom were females(kg/m2) was calculated using the individual’s (n = 167; 51.4%). The mean age (±S.D.) ofheight and weight, and classified according to the respondents’ was 21.77 ± 1.1 years old,WHO (WHO 2006). The BF% was classified with almost half of them (50.1%) at the age ofbased on American College of Sports Medicine 22 years. The present study revealed that the(American College of Sports Medicine 2009). respondents had varying background educationThe WC was based on (International Diabetes levels such as diploma (45.5%), STPM (A-levelFederation International Diabetes Federation equivalent) (28.6%), SPM (O-level) (23.4%)2006). A blood sample was drawn from a and matriculation (2.5%). The majority ofsubsample of 162 respondents (79 males and 83 the respondents lived on campus (63.0%),females) by proportionate stratified sampling, additionally most of the respondents receivedwhereby, every other respondent was chosen scholarships (79.3%) to pursue their studies.from the total population list (n = 324). The mean (±SD) of BMI of the A finger prick sample of blood was drawn respondents was 22.5 ± 4.18 (kg/m2). Theby a trained laboratory technician to measure findings are similar to another local universityhaemoglobin, blood glucose and blood lipids study (Quah & Zaitun 2005). Although(serum total cholesterol, HDL-cholesterol, the majority of the respondents were ofLDL-cholesterol, and triglycerides) by average BMI, 14% of the respondents werethe Reflotron® Plus instrument (ROCHE, underweight and 21% were overweight andSwitzerland). The cut-off point for hemoglobin obese (Table 1). However, the mean (±SD)was based on WHO (WHO 2001). To measure BMI of the male students (23.0 ± 3.9 kg/m2)Maximum Aerobic Capacity (VO2max) was slightly higher than that of female studentslevelrespondents had to perform the Queens (22.0 ± 4.3 kg/m2). Similar findings were alsoCollege Step test (McArdle et al. 1972). reported in another study (Saat et al.2010. It isRespondents were required to do light warming- generally believed that young females desireup activities prior to actual measurements. to lose weight while young males basicallyTable 1. Distribution of Body Mass Index of the respondents.BMI (kg/m2) Mean ± S.D. n (%) (n = 324) –Overall 22.51 ± 4.18 9 (2.7)Severe thinness (<16.00) 35 (10.8)Moderate thinness (16.00–16.99) 215 (66.3)Mild thinness (17.00–18.49) 45 (13.9)Normal (18.50–24.99) 14 (4.3)Overweight/pre-obese (25.00–29.99) 5 (1.5)Obese 1 (30.00–34.99) 1 (0.5)Obese 2 (35.00–39.99)Obese 3 (>40.00)Note. Data are expressed as n (%) unless otherwise indicated.Based on BMI classification by World Health Organization 2006 39

ASEAN Journal on Science and Technology for Development, 30(1&2), 2013would like to gain weight. The weight gain in lipid profiles in 2008 (Lee et al. 2010), whichmales is commonly due to increase in muscle may be due to the younger age group (18–25mass. Females are more likely to go on a diet years old) in the present study. While, inand try other weight-loss practices just to have haemoglobin measurement (Table 3), mild orlower body weight. Nevertheless, the majority moderate anaemia was reported in the current(66.3%) of the respondents had normal BMI. study (34.5%), which is slightly higher when compared to another study conducted in Tuaran The majority of the respondents (93%) District of Sabah (Leng et al. 2004).were in the normal WC range. The mean (± SD)of WC was 74.3 ± 9.01 (cm) for males and Table 2. Lipid profile of the respondents68.7 ± 9.77 (cm) for females, which were (n = 162).within the normal range. The MalaysianNCD surveillance (MyNCDs-1) among 2572 Lipid (mmol/l) Mean ± S.DMalaysian adults (25–64 years old) using theInternational Diabetes Federation (IDF) cut- Serum total cholesterol 4.29 ± 0.79off points, reported a higher prevalence of HDL-cholesterol 0.75 ± 0.18abdominal obesity at 48.6% for women and LDL-cholesterol 2.98 ± 0.5940.7% for men (Disease Control Division, Triglycerides 1.10 ± 0.62Ministry of Health 2006). The difference in thepresent study might be attributed to the larger Note: Data are expressed as n (%) unless otherwiseproportion of the younger age group from indicated.18 to 25 years old. Nevertheless, the presentstudy revealed that WC was comparable other Based on cut-offs by International Diabetics Federationlocal university students (Gan et al. 2011). The 2006mean body fat percentages (BF%) of the maleand female respondents was 16.4 ± 5.98% and The majority of the respondents had poor26.0 ± 5.50%, respectively. aerobic capacity (70.7% males and 25.7% females) (Table 4). It is also noted that the male The mean (± SD) blood glucose (5.7 ± respondents generally had a higher VO2max than0.95 mmol/l) was within the normal range, their female counterparts. The VO2max valuesbased on Clinical Practice Guidelines — of the present study (51.17 ± 3.93 ml/kg/min)Management of Type 2 Diabetes Mellitus 2009, were lower when compared with another studyfor 94.4% of the respondents, and there was (56.8 ± 3.5 ml/kg/min) (Singh et al. 1989).no significant difference observed within eachgender. In addition, in the present study, the Although our study relied on the inclusionglucose reading was similar to fasting blood of a large, convenient sample, a major limitationglucose of Malaysians in 2008 (Lee et al. 2010). still exists, data were self-reported and cross- sectional (does not infer causal relationships). As presented in Table 2, the mean (± SD) The limited blood samples are obtained that mayof the respondents’ serum total cholesterol, not be able to give comprehensive metabolicHDL-cholesterol, LDL-cholesterol and profiles. The aerobic capacity measurementtriglycerides were 4.3 ± 0.79 (mmol/l), 0.8 ± may need to include lab protocol using0.18 (mmol/l), 3.0 ± 0.59 (mmol/l) and 1.1 treadmill to obtain actual aerobic capacity.± 0.62 (mmol/l), respectively. The current Food consumption should have been obtainedfindings reveal that total cholesterol levels were which will able to portray the eating habits aslower when compared with data on Malaysian well as energy consumption. Due to the lack of direct physical activity and food consumption assessment in our current study, concrete evidence to support this finding requires further investigation. 40

M. Emad et al.: Physical Fitness and Metabolic Profile among Malay Undergraduates of a Public UniversityTable 3. Distribution of haemoglobin of the respondents by gender.Haemoglobin (g/l) Mean ± S.D n (%) (n = 162)Male (n = 79) 147.4 ± 14.9 –Severe anemia (< 80) 122.9 ± 13.7 –Moderate anemia (80–109) 19 (24.0)Mild anemia (110–129) 60 (76.0)Non-anemia (≥ 130)Female (n = 83) -Severe anemia (< 80) 3 (4.5)Moderate anemia (80–109) 34 (40.1)Mild anemia (110–119) 46 (55.4)Non-anemia (≥ 120)Note. Data are expressed as n (%) unless otherwise indicated.Based on cut-offs by WHO, UNICEF, UNU2001Table 4. Distribution of VO2max of the respondents by gender.VO2max (ml/kg/min) Mean ± S.D n (%) (n = 324)Male (n = 157) 51.17 ± 3.93 16 (10.2)Excellent (≥48.20) 38.82 ± 3.93 16 (10.2)Good (44.23–48.19) 14 (8.9)Fair (40.98–44.22) 111 (70.7)Poor (<40.98)Female (n =167) 13 (7.8)Excellent (≥40.98) 29 (17.4)Good (36.65–40.97) 82 (49.1)Fair (33.76–36.64) 43 (25.7)Poor (<33.76)Note. Data are expressed as n (%) unless otherwise indicated.Based on cut-offs American College of Sports Medicine 2006 The metabolic risk factors for cardiovascular (National Health and Morbidity Survey 2011).disease and Type 2 diabetes are increasingly The respondents’ blood profiles were good;apparent in young adults (Ramachandran et al. BF% and WC are within normal range.2012). There is no data available on physical Conversely, the poor aerobic capacity, whichfitness among younger age group in Malaysia. means they are not physically fit, may predisposePhysical fitness and physical activity are to non-communicable disease in future.strong determinants for health outcomes. Infit individuals, confer a lower metabolic risk CONCLUSIONprofile. It is noted from recent National HealthMorbidity Survey (NHMS), Malaysian are The current study provides important insightgenerally inactive and non-communicable into the level of physically active lifestylesdisease increasingly apparent in adults and metabolic profile in the university-aged 41

ASEAN Journal on Science and Technology for Development, 30(1&2), 2013population, revealed that the respondents in REFERENCESthis study have low physical fitness level, andthere is evidence of under- as well as over- American College Health Association 2005,‘Thenutrition (overweight and obese) issues among American College Health Association Nationalundergraduates. Despite knowing the health College Health Assessment (ACHA-NCHA)’,benefits associated with an active lifestyle, Spring 2003 reference group report, Journal ofthe majority of young adults do not engage in American College Health, vol. 53, pp. 199–210.sufficient levels of physical activity. Increasingphysical activity and obesity prevention has American College of Sports Medicine 2009, ACSM’sbeen identified as the top priorities in the guidelines to exercise testing and prescription,national health agenda, which may require 8th edn, Baltimore: Williams & Wilkins.additional focus among university students.PA needs to be increased and emphasized Ansari,W & Stock, C 2010, ‘Is the health andduring university life because it is likely that wellbeing of university students associated withthe undergraduates may persist in this low their academic performance? Cross sectionallevel of PA, or even decrease it further in findings from the United Kingdom’, Internationalthe years following graduation. Establishing Journal of Environmental Research and Publichealthy lifestyle from the time they are in Health, vol. 7, pp. 509–527.university would ensure that they are in betterhealth when they enter the workforce where Cochran,WG 1977, Sampling techniques, 3rd edn,stress levels and time demands will be even New York, John Wiley.greater. Additionally, it is also important thatvarsity-aged students are educated concerning Flegal, K, Carroll, J,Ogden, C & Johnson, C 2003,how important is the simple height and ‘Prevalence and trends in obesity among USweight measurement to calculate the BMI and adults 1999-2000’, Journal of the Americanunderstand that this measure is abasic health- Medical Association, vol. 286, pp. 1195–1200.screening tool. On the other hand, the universityshould also incorporate a health promotion Gan, WY, Mohd, NMT, Zalilah, MS & Hazizi, ASprogramme propounding PA and nutrition into 2011, ‘Differences in eating behaviours, dietarythe university’s general education requirements. intake and body weight status between male and female Malaysian university students’, Mal. J. ACKNOWLEDGMENTS Nutrition, vol. 17, no. 2 pp. 213–228.The authors would like to thank University Institute for Public Health, Kuala Lumpur, MinistryPutra Malaysia for the technical and financial of Health, Malaysia 2011, National Health andsupport under the Research University Grant Morbidity Survey.Scheme. The authors wish to acknowledgethe Faculty of Sports Sciences and Recreation International Diabetes Federation 2006, ‘The IDF(FSR), University Technology MARA (Shah consensus worldwide definition of the metabolicAlam) and the FSR Physiology Laboratory. syndrome’, viewed 3 June 2013, <http://www.idf.The authors express their utmost gratitude to org/webdata/docs/IDF_Metasybdrome_definition.the respondents for their participation. pdf>. Date of submission: December 2013 Irwin, J 2004, ‘Prevalence of university students’ sufficient physical activity’, a systematic review, Date of acceptance: April 2014 Perceptual and Motor Skills, vol. 98, pp. 927–943. Lakka, TA, Laaksonen, DE, Lakka, HM, Ma Nnikk N, Niskanen, LK, Rauramaa, R & Salonen, JT 2003, ‘Sedentary lifestyle, poor cardiorespiratory fitness, and the metabolic syndrome’, Med. Sci. Sports Exerc., vol. 35, no. 8, pp. 1279–1286. Lee, PY, Ong, TA, Muna, S, Alwi, SSAR & Kamarudin, K 2010, ‘Do university students have high cardiovascular risk? A pilot study from 42

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ASEAN J. Sci. Technol. Dev.,  30(1&2): 44 – 49 A Preliminary Study: Comparative Toxicity of Extracts from Tinospora tuberculata Beumeeand Lumnitzera racemosa Willd on Aedes aegypti Linnaeus Larvae (Diptera: Culicidae) A. A. WAHIZATUL1* AND R. Shasita1Research has been widely made on the potential use of herbal plants as effective agents for mosquitovector control. However, only a few studies have been carried out to investigate the potentialinsecticidal activity of mangrove plants against these dengue vectors. This study was carried out toexamine the comparative toxicity of two mangrove plants, Tinospora tuberculata and Lumnitzeraracemosa against the Aedes aegypti larvae. The leaf and stem of T. tuberculata and L. racemosa,were extracted using 95% methanol and these extracts bioassayed against the 3rd instar larvae ofaegypti under laboratory conditions. The LC50 values of the crude extract of T. tuberculata stem andleaf were 0.5778 mg/ml and 0.7213 mg/ml, respectively. For L. racemosa, the LC50 value for stemwas 1.2833 mg/ml and 1.1957 mg/ml for leaf. However, no significant differences in toxicity weredetected for the stem and leaf of both plants. Both plants, especially T. tuberculata might containinsecticidal components toxic to larvae of Ae aegypti.Key words: Toxicity; Tinospora tuberculata; Lumnitzera racemosa; Aedes aegypti; herbal plants;mosquito vector; dengue vectorsSome mosquitoes are known to transmit but antigenically distinct virus serotypes,many serious diseases to humans. Among DEN-1 DEN-2 DEN-3 and DEN-4. Infectionthese mosquitoes, the commonest genus by one of these serotypes provides immunitythat bites humans are Anopheles, Culex, to only that serotype for life, so people livingAedes, Mansonia, Haemogogus, Sebethes and in a dengue-endemic area could have morePsorophora. In Malaysia, there are 381 species than one dengue infection during their lifetimein 20 genera of mosquitoes, some of which are (Glubber 1989).medically important vectors of arboviruses(Ken et al. 2002). The incidence of dengue has attained levels that are of considerable concern to local The principal mosquito vector that transmits authorities. Until today, there are no effectivethe arbovirus of dengue is Aedes aegypti. The dengue vaccines available. The only way ofdengue (Flaviviridae) virus is arguably the most decreasing the incidence of the disease is theimportant arbovirus affecting humans (Curtis suppression of Ae. aegypti. Experience has1986). Dengue fever and dengue hemorrhagic shown that spraying of chemical insecticidesfever are caused by one of four closely related against this mosquito was not effective, since1School of Marine Science and Environment, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, Malaysia.*Corresponding author (e-mail: [email protected])