RETA-IC2023 Abstract Book

SN Ammonia-free natural rubber latex: A journey with palm-based surfactants Siang Yin Lee1,*, Nurulhuda Binti Abdullah1, Fatimah Rubaizah Mohd Rasdi1, Yun Khoon Liew2, Rhun Yian Koh3, Desmond Teck Chye Ang4, Kok Chong Yong1, Kok Lang Mok1. 1Technology and Engineering Division (BTK), RRIM Sungai Buloh Research Station, Malaysian Rubber Board (MRB), 47000 Sungai Buloh, Selangor, Malaysia. 2School of Pharmacy, International Medical University, No. 126, Jalan Jalil Perkasa 19, Bukit Jalil, 57000 Kuala Lumpur, Malaysia. 3School of Health Sciences, International Medical University, No. 126, Jalan Jalil Perkasa 19, Bukit Jalil, 57000 Kuala Lumpur, Malaysia. 4Department of Chemistry, University of Malaya, Lembah Pantai, 50603 Kuala Lumpur, Malaysia. Email: [email protected]; [email protected] Abstract: We have discovered new ammonia-free natural rubber (NR) preservative system based on our in-house synthesized palm-based surfactants. This solves long-standing problems due to the negative effects of conventional ammonia, tetramethylthiuramdisulphide ( TMTD) / Zinc oxide ( ZnO) natural rubber preservative system. These problems include high volatility and toxicity of ammonia, carcinogenicity of TMTD for releasing nitrosamines and metals toxic effects in aquatic ecosystems. Besides, ammonia production is a highly energy intensive process consuming around 1.8% of global energy output each year and producing about 1.8% of global carbon dioxide emissions. Hence, it is essential to search for green, non-volatile, non-toxic and low carbon footprint stabilizing system to potentially replace ammonia ( high and low) preservative system. Given this, a series of biocompatible palm-based polymeric surfactants of anionic charges were synthesized to address these issues. These surfactants were added into freshly tapped field NRL and subjected to centrifugation to produce latex concentrates for further characterization. We report the use of the surfactants as a stabilizer to produce three types of latexes, namely fresly tapped field NR latex, low ammonia NR latex concentrates and ammonia-free NR latex concentrates was confirmed. The latex storage stability study of these latexes was found to report values within the acceptable range of standard requirements for latex stability applications. Both latex concentrates preserved by non-toxic palm-based surfactants were all within the acceptable range of standard requirements for dipping film applications. The extractable protein contents of ammonia-free latex film after subjected to wet-gel and post-cure leaching were low and the ammonia-free latex films were graded as ‘ 2’ , meaning no or low cytotoxicity. While the total bioburden of ammonia-free latex film was estimated as 6 colony-forming units or CFU. Preliminary study of the oxidative and biodegradation of ammonia-free latex films indicated certain extent of oxidative degradation has taken place in those film samples. Since these palm-based surfactants can be synthetically designed, result from this study provide a useful reference to the follow-up study to alter their functional groups and structures to enhance their functions in latex stabilization in producing ammonia-free NR specialty latexes. RETA-IC 2023 51

SN Insights into the mixing of silica-natural rubber compounds for more sustainable tire industry Ammarin Kraibut1,2, Sitisaiyidah Saiwari1, Wisut Kaewsakul3, Jacques W. M. Noordermeer2, Wilma K. Dierkes2 and Kannika Sahakaro1 1 Department of Rubber Technology and Polymer Science, Faculty of Science and Technology, Prince of Songkla University, Pattani Campus, Thailand 2 Sustainable Elastomer Systems (SES), Faculty of Engineering Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, the Netherlands 3 Elastomer Technology and Engineering (ETE), Faculty of Engineering Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, the Netherlands email: [email protected] Abstract Mixing of silica into non-polar tire rubbers for low rolling resistance tread compounds requires sufficiently high shear forces and proper discharge temperature to optimize the silanization reaction and to obtain the best possible silica-rubber interactions. A combination of both mechanical and thermal actions occurring during mixing raises a concern over natural rubber (NR) degradation. It is well known that NR is sensitive to mastication and prone to oxidation. This work aims to investigate insights into the degradation during mixing of silica-NR compounds by monitoring changes of viscoelastic responses. The silica-filled NR compounds prepared by using different dump temperatures were investigated taking pure NR and unfilled NR compounds as references. The Mooney stress relaxation rates, the dynamic properties as a function of frequency, and the delta-delta (δ∆) values according to Booij and van Gurp-Palmen plots, were used to indicate the changes in elastic-viscous responses. There are two main competitive reactions taking place during mixing: chain scission or degradation and preliminary crosslinking or branch formation. Chain scissions contribute to the viscous response whereas chain recombination and interactions promote the elastic part. For masticated pure NR and unfilled compounds, the viscous responses increase with increasing dump temperature indicating the dominance of chain scission that causes decreased molecular weight, broadened molecular weight distribution, and branched structures. For silica-filled NR compounds, the elastic response due to preliminary crosslinking and/or branching is significant at the dump temperature above 150 °C. These chain modifications introduce network heterogeneity that negatively influences the mechanical properties of the rubber vulcanizates. As NR is more sensitive to degradation than other tire rubbers, an understanding insight into the mixing of silica-NR compounds should lead to a better control of processing to optimize the properties of this sustainable material. 52 RETA-IC 2023

SN Social Issues and Technical Issues Required of the Natural Rubber Industry Naoya Ichikawa Sumirubber Thai Eastern Corporation Co., Ltd. 333 Moo.7 T.Chiang pin A.Muang Udonthani Udonthani Thailand 41000 Email: [email protected] Abstract Natural rubber is used in a wide range of products, from tires and other daily necessities to industrial products, and is an indispensable material in our lives. Along with the increase in demand, the production volume of natural rubber increased to 12.95 million tons worldwide in 2020. Thailand became the world's No. 1 natural rubber producer in 1991, and has continued to increase production since then, producing 4.5 million tons in 2020. There are many people engaged in industries related to natural rubber, from agriculture to industry in Thailand. In terms of exports, it is the second largest agricultural product after rice. As such, natural rubber has become a very important agricultural product in Thailand. Natural rubber is attracting more and more attention as an important material due to the sustainability of natural rubber itself, which is an agricultural product. There is also a growing demand for sustainability, which indicates that natural rubber is supplied without affecting forests and other natural ecosystems, and for traceability, which indicates that natural rubber is sourced from controlled production areas. There are also demands for solutions to issues such as the odor of natural rubber itself and the increase in production volume through a technical approach. In this presentation, I will explain the current situation of social and technical issues surrounding natural rubber, as well as examples of our efforts. RETA-IC 2023 53

SN Socio-Economic Perspective: The Importance of Systematic Management of NR Production towards the Sustainability of the NR Industry International Rubber Consortium (IRCo) The International Tripartite Rubber Council (ITRC) was jointly established in 2002 by the governments of Thailand, Indonesia and Malaysia as key global producers and exporters of natural rubber (NR). The collaborative efforts under the framework of ITRC are implemented to achieve a supply-demand balance to ensure adequate supply of natural rubber in the market at fair prices both for the producers and consumers. The ultimate aim for a healthy balance of NR in the global market is to achieve a long-term price trend that is stabilised, sustainable and remunerative to the farmers who are the backbone of the industry in the upstream sector. Through concerted efforts and coordinated mechanisms among the Member Countries, the Cooperation has and continues to contribute towards the sustainability of the NR industry for the betterment of all stakeholders involved. The price level of natural rubber (NR) has lifted by around 98% from an average of 62.96 US cents/kg before the establishment of the ITRC to the average of 124.89 US cents/kg after 5 years into the Cooperation. Rubber prices showed clear, positive momentum until the all-time peak in 2011, contributed largely by the economic expansion of China - the biggest consumer of NR. The smallholders continued to be compensated with better prices as the prices continued to hover above the prices prior to the incorporation of ITRC albeit moving in a 5-year declining trend from 2011 to 2015. Subsequently, rubber prices have maintained their range of 100 to 200 US cents/kg. Despite the elevated price level of NR, challenges in the NR industry remain on both the supply and demand sides. One of them is overproduction. NR producers have the tendency to overproduce as they anticipate to continue enjoying the lucrative income from NR. Over the past 5 years alone (2017 - 2021), the aggregated surplus of NR surpassed 3 million tons, adding to the already-high stock level globally. This issue of excessive supply could be attributed to two factors. That is, while demand is often overestimated, which encourages overexpansion of NR plantations, there has also been an increase in the number of NR producers and exporters. Therefore, since NR is produced mostly by smallholders and in different regions of the world, unless production management among producing countries is well coordinated, the pressing issue of oversupply will continue to have adverse effects on NR prices and, crucially, the livelihoods of those producing it. Another challenge is increasing demand for sustainable NR. Moving towards ‘sustainability’ is multifaceted. One clear aspect of sustainability is for the environment. As consumers encourage environmentally-friendly farming practices, the governments of producing countries, such as Thailand, Indonesia, Vietnam and Malaysia, have also been striving to address this issue at the farmgate level. Another aspect involves income and livelihoods of smallholders who account for more than 90% of global NR supply. Rubber prices should reflect the rising costs of production and, importantly, added costs of ‘going green’ for a more sustainable sector. Sustainable NR prices will keep smallholders in business, preventing them from switching to other crops and/or other economic activities. With remunerative income from rubber, they will most likely continue to grow and tap rubber - ensuring an adequate supply of NR for the global market and contributing to NR price stability for manufacturers and consumers. All stakeholders in NR will and should reap the benefits of the sustainability of NR. As a way forward for the two pressing issues, namely overproduction and sustainability, “collaboration and concerted efforts among NR producers” and “continuous engagement with consumers” are top priorities. Effective management of NR production and a well-strategized path to sustainability shall lead to the betterment of stakeholders on both the supply and demand sides of the industry. 54 RETA-IC 2023

SN Potential of Rubber Seed Oil for Producing Biodiesel Fuel in Thailand Koryu Kawatani1, Huynh Phuong Uyen Nguyen1, Krit Somnuk2 , Ekwipoo Kalkornsurapranee3,   Ye Min Oo2, Jarernporn Thawornprasert2, Kritsakon Pongraktham2   1Innovare Co. Ltd., Soken-Midosuji-Build. 2F 3-5-13, Awajimachi, Chuo-ku, Osaka, Osaka 541-0047 Japan; 2Department of Mechanical and Mechatronics Engineering, Faculty of Engineering, Prince of Songkla University, Hat Yai, Songkhla, Thailand, 90110; 3Natural Rubber Innovation Research Institute, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla, Thailand, 90110 Author Email: [email protected] Abstract Introduction: The rubber plantation area in Thailand extends to around 3,960,520 ha[ 1] . Rubber seed oil (RSO) contained in Rubber Seed (RS) has the potential of raw material for biodiesel fuel. On the other hand, Fig. 1. Procedure of RSO extraction RSO has high Free Fatty Acid(FFA), and it prevents effective biodiesel production. That is why RSO is not commonly used so far. We at Prince of Songkla University (PSU) and Innovare experimented with utilizing this RSO for producing biodiesel fuel and successfully produced the high FAME yield biodiesel fuel. We would like to contribute to rubber plantations to make alternative income and contribute to the renewable energy sector in Thailand. Experimental: In the recent work, we collected rubber seeds (RS) from rubber plantations in Chiang Mai, Surat Thani, and Songkhla, Thailand, then investigated the properties of seeds, analyzed the compositions of extracted RSO, and then produced biodiesel from RSO. Fig.1 shows the procedure of RSO extraction. Collected RS was dried using the oven at a temperature of 110oC for 6 hours. Dried RS were split into shells and kernels, then ground kernel into powder and extracted oil using hexane with a ratio of around 1: 6. We checked RSO's physicochemical characteristics and produced biodiesel by alkaline-catalyzed transesterification reaction on a laboratory scale. Results and Discussions: Table 1 shows the RSO compositions in each area. The percentage of FFA in RSO in our project shows not-high free fatty acid content, like Chiang Mai:1.55%, Surat Thani:0,21%, and Songkhla: 3,3% . We consider that collecting fresher RS and prompt treatments Table 1. RSO compositions from solvent extraction to stop the enzymatic action/ hydrolytic reaction would work effectively. After - FFA(% ) TG (% ) DG(% ) MG(% ) extracting RSO, we applied a two- stages- Songkhla 0.7-3.3 94-99 0.3-2.8 - method of esterification reaction followed by transesterification reaction and Surat Thani 0.21 99.41 0.3 0.08 successfully obtained high FAME- yield ChiangMai 1.55 97.89 0.51 0.05 biodiesel with 97.73%. In conclusion, PSU and Innovare confirmed that we could produce high FAME-yield biodiesel from RSO. Moreover, we can show the potential of RSO as a raw material of biodiesel. Furthermore, PSU and Innovare will improve the biodiesel production method to produce more effectively to realize our positive social impact and carbon-neutral society in Thailand and the world. References [1] Office Agricultural Economics, Forecasting Agricultural Crop Year 2563. 2020. [2] Widayat, A.D.K. Wibowo and Hadiyanto, Energy Procedia. 2013, 64–73. [3] H. N. T. Le, et al., Chem. Eng. Technol., 2018, 41, 1–7. [4] J. Ahmad, S. Yusup, A. Bokhari and R.N.M. Kamil, Energy Convers Manag. 2014, 78, 266–275. RETA-IC 2023 55

SN Progress of production trials of low-protein NR gloves Piyada Suwandittakul, Suriyakamon Montha, Chayanoot, Preeyawis Na Ubon, Pipatcha Rakdee, Chaveewan Kongkaew National Metal and Materials Technology Center, Innovative Rubber Manufacturing Research Group, Pathum Thani 12120, Thailand email: [email protected] Abstract In the global glove market share, it is found that synthetic rubber gloves have a market share of about 70 percent, while NR gloves have only 30 percent. This may be due to the fact that the major rubber glove importing countries, especially the United States, are concerned about allergies to the NR gloves. In the future, the market share of NR gloves will decrease if the allergy problems are not resolved. Natural rubber (NR) latex contains more than 250 proteins, of which 15 are allergenic proteins. The allergenic proteins found in significant amounts in NR gloves are Hev b 1, Hev b 3, Hev b 5, and Hev b 6.02. This study aims to solve the problem of protein allergies in NR gloves by using the Maillard reaction to crosslink protein molecules in NR gloves. This technique can be applied for the preparation of low-protein NR gloves in both off-line and on-line processes. The results showed that the low-protein NR gloves had good physical properties, while the quantities of soluble protein content and allergenic protein content were less than 20 µg/g and 0.5 µg/g, respectively. Various factors, such as latex sources, latex season, and latex age, did not affect the protein crosslinking efficiency in the NR gloves. Keywords: NR gloves, protein allergy References [1] E. Yip, P. Cacioli, J Allergy Clin Immunol. 2002, 110: S3-14. [2] S. Montha, P. Suwandittakul, A. Poonsrisawat, P. Oungeun, and C. Kongkaew, Adv. in Mater. Sci. Eng. 2016, 1-6. [3] C. Kongkaew, A. Poonsrisawat, V. Champreda, and S. Loykulnant, J. Appl. Polym. Sci. 2017, 314, 45224. [4.] C. Kongkaew, W. Intiya, S. Loykulnant, and P. Sae-oui, Kautsch. Gummi. Kunstst. 2017, 5, 37-41. 56 RETA-IC 2023

SN Ultra-low-ammonia Latex Suriyakamon Montha, Piyada Suwandittakul, Pipatcha Rakdee, Chaveewan Kongkaew National Metal and Materials Technology Center, Innovative Rubber Manufacturing Research Group, Pathum Thani 12120, Thailand email: [email protected] Abstract Concentrated NR latex is a significant raw material for making rubber products used in daily life such as rubber glove, condom, nipple, thread, balloon and rubber foam, etc. However, concentrated NR latex consists of toxic preservatives such as ammonia, tetramethylthiuram disulfide and zinc oxide. Therefore, ultra- low ammonia concentrated latex ( ULA latex) is developed to solve the problems from toxic chemicals in the concentrated NR latex, even to create new alternative NR products using green and safe concentrated NR latex as raw material. Research and development of ultra- low ammonia concentrated latex (ULA latex) covers the source of fresh latex (East and South) and 3 seasons. The production process of the ULA latex is shown in Figure 1. The ULA latex is produced by industrial high- speed centrifuges. The ULA latex contains ammonia in the range of 0.10-0.15%, potassium hydroxide in the range of 0.10-0.30%, and potassium laurate in the range of 0.03-0.08%. The ULA latex production cost is comparable to commercial latex. Its properties meet the requirements of TIS 980-2552 and ISO 2004: 2017. The ULA latex has lower ammonia evaporation and less coagulum content in the temperature range of 4-120 °C than the commercial latex. Gas sensing electrode method is used to efficiently analyze the ammonia content in the latex. We have initiated to push ULA latex into national standards (TIS 980-2552) and international standards (ISO 2004: 2017). We have been successful in making rubber products such as PARA AC (asphalt mixed NR), rubber foam, rubber gloves and soothers both at the laboratory, field and industrial level. Currently, we have already transferred the production and commercial use of ULA latex to manufacturers in the rubber industry. Figure 1. ( a) LA, MA or HA commercial latex production process and ( b) ULA latex production process RETA-IC 2023 57

ABSTRACTS TE Rubber Technology and Engineering

TE Development of Cure Optimization using Arrhenius Model Yen Wan NGEOW1 1 Elastomer Innovation and Technology Unit, Technology and Engineering Division, Malaysian Rubber Board, Experimental Station, 47000 Sg. Buloh, Selangor, Malaysia Email: [email protected] Abstract: The rubber industry faces continuous challenges in optimizing the curing conditions of their rubber products. The vulcanization behaviors of rubber mixtures are affected due to the changes in chemicals, compound formulations or curing instruments. In the interest of achieving good factory productivity by overcoming the temperature variation in a curing chamber or thick rubber article with high ‘ thermal lag’ , the cure curve at different inflection points was measured using a rubber process analyzer (RPA). The cure rate factor chart and the equivalent cure time were developed by performing the Arrhenius model. In this work, the vulcanization process for a rubber compound is considered as a first-order reaction. 10% and 90% torques changed were used to estimate the cure rate constant for rheometer isotherms ranging from 120 ºC to 140 ºC. The apparent activation energy of the rubber compound at different temperatures was also determined. The study showed that RPA variable temperature analysis can be used to determine an appropriate cure time for a vulcanization system in question to reach a ‘satisfactory state’ of cure. Keywords: Arrhenius Model, Cure Kinetics, Activation Energy; Vulcanization RETA-IC 2023 59

TE Structure and Properties of Vulcanized Natural Rubber Seiichi Kawahara and Masaki Yamano Department of Materials Science and Technology, Nagaoka University of Technology, 1603-1, Kamitomioka- machi, Nagaoka, Niigata, 940-2188, Japan email: [email protected] Abstract A long sequence of cis-1,4-isoprene units may accomplish outstanding mechanical properties of vulcanized natural rubber since it results in a high strain-induced crystallizability of the rubber. To achieve the long sequence of cis-1,4-isoprene units, the vulcanized natural rubber is required to consist of both cis-1,4-isoprene units and cross-linking junctions without other structural units. In the previous works, the vulcanization of natural rubber was studied by measuring the mechanical properties of the rubber. However, the reactions were not investigated by structural analysis since no analytical method was applicable for the vulcanized natural rubber. Recently, we developed a rubber- state NMR spectroscopy as a powerful technique for the structural analysis of the vulcanized rubbers. In the present study, the vulcanized natural rubber prepared at various temperatures were characterized by rubber-state NMR spectroscopy with inverse gated decoupling method. Content of the cis-1,4- isoprene units, estimated from intensity ratios of the signals, were directly related to the mechanical properties. Fig.1 shows solution-state 13C-NMR spectrum for un-vulcanized natural rubber and rubber-state 13C-NMR spectra for the vulcanized Fig. 1 13C-NMR spectra for (a) NR and vulcanized natural rubbers natural rubberes prepared at 110，130，150 and prepared at (b) 110, (c) 130, (d) 150 170 oC, respectively. Small signals appeared at 37, and (e) 170 oC. 40, 44.5, 50, 50.5, 57 and 58 ppm in the rubber-state 13C-NMR spectra for the vulcanized natural rubbers, which were assigned to carbon atoms of the trans-1,4-isoprene unit and structure of crosslinking junctions, I – IV, shown in Fig.1, respectively. Intensities of signals at 40, 57, 58 ppm were increased as vulcanization temperature increased; that is, content of cis- 1,4-isoprene units of the vulcanized natural rubber decreased as vulcanization temperature increased. Fig.2 shows a plot of stress at break versus temperature. A value of the stress at break at 20 oC was 25 MPa for the vulcanized natural rubber prepared at 130 oC and it decreased in the order of the vulcanization temperature of 130, 150, 110, 170 oC. It is, thus, found that 130 oC is the most suitable Fig. 2 Plots of stress at break versus vulcanization temperature to prepare the temperature for vulcanized natural strain-induced crystallizable vulcanized rubbers prepared at 110, 130, 150 and 170 natural rubber. 60 RETA-IC 2023

TE Fabrication of superhydrophobic natural rubber via graft copolymerization: Preparation and application Kotchamon Yimmut, Patchararujee Ngamdee, Napida Hinchiranan Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand Center of Excellence of Petrochemical and Materials Technology, Chulalongkorn University, Bangkok, Thailand email: [email protected] Abstract Natural rubber (NR) is one of bio-based materials, which are extensively applied in medical-healthcare devices. A clogging or bacterial attachment onto product's surface can be avoided by creating the non- fouling surface for extending the NR utilization. Although NR has hydrophobicity in nature, this presentation will give the idea to enhance this property via 2 methods: 1) graft copolymerization with monomers having low surface energy such as 2,2,2-trifloroethyl methacrylate (3FMA) and 2) two-step surface modification involving sulfuric acid (H2SO4)-catalyzed hydration to form hydroxyl (-OH) functional groups on the rubber surface followed by grafting with methyltrichlorosilane (MTCS). For the first method, butyl acrylate (BA) acted as a co-monomer to be initially grafted onto NR and then copolymerized with 3FMA to form a grafting poly(BA-co-3FMA) chain onto the NR backbone (NR-g- poly(BA-co-3FMA)) in the latex state. The appropriated BA/3FMA ratio at 30/70 (w/w) provided the highest graft copolymer fraction of 72.8 wt% with 25.3 mol% grafted 3FMA and 68.5% grafting efficiency under center reaction condition. From the morphology analysis, the obtained graft product was core-shell type consisting of NR as a core covered by poly(BA-co-3FMA) shell. After applying the graft product as a compatibilizer for NR/poly(BA-co-3FMA) films (20/80 (w/w)), the compatibilized films exhibited a high hydrophobicity (water contact angle = 109°) and oleophobicity (hexadecane contact angle = 54°) with a low surface energy (8.04 mN/m), which can be further applied as self-sealing films for moisture and oil protection. For another route, the surface modification was performed using vulcanized NR film (VNR). After immersing VNR in 75 wt% H2SO4 solution for 1 h, the OH groups were formed on the VNR surface and expected to act as the active sites for grafting with MTCS via hydrolysis and polycondenzation to obtain a VNR-OH-MTCS film. The water contact angle (WCA) of the VNR-OHMTCS film prepared by using 2 wt% MTCS concentration was greatest at 155. Moreover, the modified film exhibited the flexibility with ability to inhibit the formation of a bacterial biofilm. Not only superhydrophobicity, the VNR-OH-MTCS film also had oleophilicity (oil absorption capacity [k] of 1.13) suggesting that it could be applied for oil/water separation with high separation efficiency of 98.6%. References [1] K. Yimmut, K. Homchoo and N. Hinchiranan, Colloids Surf .A .2018, 540 2018, 11-22 . [2] P. Ngamdee, K. Yimmut and N. Hinchiranan, Polym. Adv. Tech. 2022, 33, 1146. RETA-IC 2023 61

TE An investigation of through-thickness porosity in CFRP by image processing techniques Sawanya Suwannawong1, Pimpet Sratong-on1 1 Faculty of Engineering, Thai-Nichi Institute of Technology, 1771/1 Pattanakarn Rd. Suanluang, Bangkok, 10250, Thailand. e-mail: [email protected] Abstract Porosity in carbon fiber reinforced plastics (CFRPs) has been reported as having a significant impact on the mechanical properties. Several techniques are performed in porosity analysis, such as digital image processing. One of the efficient image analysis methods is a thresholding process which is based on image segmentation by adjusting threshold level. To enhance the simplicity of the method, the thresholding is carried out to measure the content of the composition, i.e., void, fiber, and matrix, on through-thickness cross-section microscopic images. A threshold level range that depends on brightness is selected to highlight each composition. The measured area at different threshold levels indicates a fraction of the composition as presented in Figure 1. The results show that the specimen contains 0.54% porosity, 60.58% fiber, and 38.88% matrix, which the volume fraction of fiber and matrix are close to value indicated in the technical data sheet from maker (Delta-Tech, Italy). Thus, the proposed basic image processing techniques can identify through-thickness porosity. Moreover, this work suggests a configuration for visible void measurement to present void properties. Acknowledgements This project was supported by Thai-Nichi Institute of Technology (project 2102/A004) and Takahashi Industrial and Economics Research Foundation for fiscal year 2021-2022. Authors are grateful to Mr.Praprut Prommachat for technical supports of fabrication of the carbon fiber prepreg specimens. References [1] S. Fanni, Master’s Thesis, KTH, Stockholm, Sweden, 2020. [2] J. G. Díaza, J. León-Becerraa, A. D. Pertuz et al., Mat. Res. 2021, 24 (Suppl 2): e20220049. [3] F. Monticeli, H. Voorwald, M.O. Cioffi, H. Altenbach et al. (Eds.), CAMPE 2021, LNME, pp. 265– 273, 2023. 62 RETA-IC 2023

TE - Poster The influence of processing parameters on the process and product properties of PLA/NR blown films Chananchida pongpakdeea and Cattaleeya Pattamaproma* a Research Unit in Polymer Rheology and Processing, Department of Chemical Engineering, Faculty of Engineering, Thammasat University, Pathumthani 12120, Thailand *Corresponding author: [email protected] Abstract This research investigated parameters involved in pilot- scale production of compounds from the blends of poly lactic acid (PLA) and natural rubber (NR) for film blowing application. The process parameters investigated here included screw speed, output rate, number of compounding step and screw configuration. The effect of these parameters on the stock temperature, retention time, die pressure and die temperature were analysed and correlated. The compounds were also characterized for their morphology, melt flow index and film processibility, whereas the films were characterized for their surface appearance, transparency, and mechanical properties. Keywords: Poly (lactic acid) (PLA), Natural rubber, Film Blowing, Twin-screw extruder, Process condition Acknowledgements The authors are grateful to Thammasat University Research Fund for the financial support. References [1] Cattaleeya Pattamaprom, Wilaiporn Chareonsalung, Chanpen Teerawattananon, Suwit Ausopron, Paweena Prachayawasin, Peter Van Puyvelde. Improvement in impact resistance of polylactic acid by masticated and compatibilized natural rubber, 2016, 25, p. 169-178 [2] Harold F.Giles, Jr., John R. wagner, Jr., Eldridge M. Mount, III . Extrusion The Definitive Processing Guide and Handbook, 2004, p. 162-163 RETA-IC 2023 63

ABSTRACTS AP Science Advancement and Prospects of Rubber and Elastomer

AP Prevulcanized epoxidized natural rubber latex blended with zinc oxide nanoparticles and phosphoric acid for anti-corrosion coating Rattapol Pornprasit1, Talan Tanto2, Pacharawan Siri2, Pramuan Tangboriboonrat3, Philaiwan Pornprasit2 1 Department of Computer Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai 50200, Thailand 2 Program in Rubber and Polymer Technology, Faculty of Engineering and Agro-Industry, Maejo University, San Sai, Chiang Mai 50200, Thailand 3Department of Chemistry, Faculty of Science, Mahidol University, Rama 6 Road, Phyathai, Bangkok 10400, Thailand e-mail: [email protected] Abstract This research involves the preparation of sulfur prevulcanized epoxidized natural rubber (ENR) latex and its use as anti-corrosion coating of steel. The ENR latex (54%mol epoxidation), prepared via the in-situ epoxidation using formic acid/hydrogen peroxide at 70ºC for 24 h, was blended with the synthesized ZnO nanoparticles (NPs) and phosphoric acid (PA), i.e., ENR-ZP, and then casted on a steel. Results showed that the added ZnO NPs significantly improved the anti-corrosion properties of low carbon steel whereas phosphate groups could enhance the adhesion between the coating film and substrate, and hence, its anti-corrosion properties. The phosphate functional group could anchor on the metal surface with covalent bonds which turned the hydrophilic groups into the hydrophobic groups (Fig.2). Therefore, the PA acts as the crosslinking bridge between the ENR-ZP film and metal surface. With adding ZnO NPs (0.5 part per hundreds of rubber; phr) and PA (1 phr), the composite ENR-ZP film could protect the corrosion of steel dipped in 48% NaOH and 10% NaCl. However, the corrosion of steel still occurred when applying 37% HCl, 48% HNO3, 96% H2SO4. The corrosion resistance in 37% HCl of the composite ENR-ZP latex film was better than that of the commercial painting. The good distribution of ZnO NPs and PA in both the ENR and NR latex was supported by the increase in thermal stability of the rubber films determined from thermogravimetric analysis. Fig. 1 TEM micrograph of ZnO NPs Fig. 2 Schematic illustration of the adhesion of ENR-ZP film and steel via phosphate group [1] Acknowledgements This research work was supported by the Faculty of Engineering and Agro-Industry, Maejo University (MJU. 2- 64-008) and the Program Management Unit for Human Resources & Institutional Development, Research and Innovation (B05F640078). References [1] L. Gu, J. H. Ding, S. Liu, and H. B. Yu, Chinese J. Chem. 2016, 29(2), 271. [2] R. Yoksan, Agric. Nat. Resour. 2008, 42(5), 325. [3] P. Chamnanvatchakit, T. Prodpran, S. Benjakul, and S. Prasarpran, Indian J. Sci. Technol. 2015, 8(36), 1. [4] S. Chimenti, J. M.Vega, M. Aguirre, E. García-Lecina, J. A.Díez, H. J. Grande, M. Paulis, and J. R. Leiza, J. Coat. Technol. Res. 2017, 14(4), 829. RETA-IC 2023 65

AP Metal ions Cross-links of Epoxidized Natural Rubber Kriengsak Damampai1, Kamonthip Rittimas1, Skulrat Pichaiyut1, Amit Das2, Charoen Nakason1 1Faculty of Science and Industrial Technology, Prince of Songkla University, Surat Thani, Thailand 2Leibniz-Institut fur Polymerforschung Dresden e.V., D-01069, Dresden, Germany. Abstract The aim of this study was to investigate the crosslinking behavior of epoxidized natural rubber (ENR) with epoxide content of 50 mol% (i.e., ENR-50) and unmodified natural rubber (NR) when compounded with various metal ions (Fe3+, Co2+, Zn2+, Mg2+, and Sn2+), in order to verify the coordination reactions and internal polymerization of epoxirane rings in ENR molecules with the assistance of the metal ions. The study investigated the cure characteristics, mechanical properties, and infrared spectroscopy of the rubber and its compounds with various metal ions. The results showed that the NR compounded with metal ions did not exhibit any crosslinking reaction, as indicated by the flat torque-time curve observed at 160°C. In contrast, the ENR-50 compounds with Fe3+, Co2+, Zn2+, Mg2+, and Sn2+ showed marching cured curves with differences in delta torques and cure rate index (CRI). The infrared spectra also revealed newly formed linkages between epoxirane groups and metal ions. The study also investigated different curing temperatures (150°C, 160°C, 170°C, and 180°C) and found that the curing reaction was more pronounced at higher temperatures, with the optimal curing temperature being about 170°C. These rubber compounds have the potential to be tailored to specific properties by adding various fillers and additives, making them suitable for use in conductive rubbers and self-healing elastomers for various industrial applications. Acknowledgements This work was supported by the National Research Council of Thailand, which provided funding through the Royal Golden Jubilee Ph.D. Program (Grant No. PHD/0121/2560). In addition, partial scholarship support was received from Prince of Songkla University in Thailand and the Leibniz-Institut für Polymerforschung Dresden e. V. (IPF) in Dresden, Germany. References [1] Damampai, K., Pichaiyut, S., Stöckelhuber, K.W., Das, A., Nakason, C. Polymers. 2022, 14, 4392. [2] Damampai, K., Pichaiyut, S., Das, A., Nakason, Exp. Polym. Let. 2022, 16, 812. [3] Mandal, S., Simon, F., Banerjee, S.S., Tunnicliffe, L.B., Nakason, C., Das, C., Das, M., Naskar, K., Wiessner, S., Heinrich, G., Das, ACS Applied Polymer Materials, 2021, 3, 1190. 66 RETA-IC 2023

AP Surface Segregation of Functional Siloxane-Based Cages in a Polymer Matrix Kensuke Naka Faculty of Molecular Chemistry and Engineering, Kyoto Institute of Technology, Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan email: [email protected] Abstract Siloxane-based cage compounds such as polyhedral oligomeric silsesquioxanes (POSS) with hydrophobic organic substituents have lower surface energy. Therefore, they are considered a promising candidate as surface modifiers. Keiji Tanaka et al. reported that terminal POSS units in poly(methyl methacrylate) (PMMA) promoted surface segregation in a PMMA film.[1] We collaborated with Keiji Tanaka and found that a star-shaped POSS, where a central octasilicate core unit is tethered to eight isobutyl-substituted POSS cages, was more effectively covered on the surface of PMMA due to non- crystallized character of the star-shaped architecture.[2] We also reported that hybrid polyurethanes composed of isobutyl-substituted open-cage silsesquioxane in the main chains (PU-POSS) showed excellent optically transparency and surface hydrophobicity and applied them as surface modifiers in PMMA by surface segregation to create hydrophobic surfaces.[3] Although the surface segregation approach can increase the hydrophobicity of polymer surfaces, it is still a challenge to make the surfaces hydrophilic in an equivalent method. We demonstrated that segregation of octa(dimethylsilylhydroxyethoxypropyl)silicate (OS-EGMAE), as a hydrophilic siloxane-based cage compound, occurred on the surface and interface of PMMA casting films without assistance of contacting high-free-energy media.[4] Addition of small amounts of OS- EGMAE in PMMA significantly enhanced wettability and the lowest static contact angle of water of 28.9±0.5˚ was observed for the cast film containing 4 wt% OS-EGMAE. These findings clearly suggest that the siloxane-based cage frameworks are promising candidates for promoting surface segregation because of their predominantly contributed entropy factor to the total free energy. Figure 1. Schematic images of surface segregation of PU-POSS and OS-EGMAE in PMMA. References [1] Matsuno, H.; Tsukamoto, R.; Shimomura, S.; Hirai, T.; Oda, Y. Tanaka, K. Polym. J. 2016, 48, 413−419. [2] Yamamoto, K.; Kawaguchi, D.; Abe, T.; Komino, T.; Mamada, M.; Kabe, T.; Adachi, C.; Naka, K.; Tanaka, K. Langmuir 2020, 36, 9960−9966. [3] Ueda, Y.; Imoto, H.; Okada, A.; Xu, H.; Yamane, H.; Naka, K. Polym. Chem. 2021, 12, 2914−2922. [4] Tokuami, I.; Suzuki, R.; Nagao, M.; Okada, A.; Imoto, H.; Naka, K. ACS Appl. Polym. Mater. 2022, 4, 5413−5421. RETA-IC 2023 67

AP Radiation vulcanization of natural rubber latex and its applications Panithi Wiroonpochit1 1 National Metal and Materials Technology Center, National Science and Technology Development Agency, 111 Thailand Science Park, Phahonyothin Rd., Khlong Nueng, Khlong Luang, Pathum thani, Thailand. email: [email protected] Abstract Radiation vulcanization of natural rubber (NR) is one of the promising ways to create hypoallergenic rubber products because this system needs less or no vulcanizing agent and can reduce allergic proteins in the latex. Radiation, such as ultraviolet (UV) and electron beam (EB), can be used to develop three- dimensional (3D) network structures of natural rubber to improve its physical and mechanical properties. The exposure to radiation causes massive free radicals in the system, and as a result, crosslinking and chain scission take place simultaneously depending on the amount of radiation dose and initiator. In the case of UV, pre-vulcanization of a heterogeneous system, like NR latex, is difficult because the penetration depth of UV is quite low and rubber particles also scatter the UV light having a similar or smaller wavelength. However, the UV pre-vulcanization of NR latex can occur with the assistance of the proper kind of photo-initiator and coagent, together with a special reactor that allows good circulation of NR particles in the latex. Under the proper conditions, the produced UV-pre- vulcanized NR films had nearly 4-5 times of un-pre-vulcanized NR films. In the case of EB, the penetration depth and radiation dose are proportional to the energy of the electrons and the density of the material. Higher electron energies (from KeV to MeV) are capable of thoroughly crosslinking polyisoprene in NR latex. Their physical and mechanical properties are improved without using any initiators. Acknowledgements This work was supported by a research grant from National Metal and Materials Technology Center (MTEC), National Science and Technology Development Agency (NSTDA), Thailand, and National Research Council of Thailand (NRCT). References [1] P. J. Scott, R. Christopher, K. D. Feller, V. Meenakshisundaram, C. B. Williamsb, T. E. Long, Polym. Chem., 2020,11, 3498-3524 [2] S. Schlögl, A. Temel, R. Schaller, A. Holzner, W. Kern, J. Appl. Polym. Sci. 2012, 124, 3478. [3] K. Makuuchi, An introduction to radiation vulcanization of natural rubber latex, 2003 [4] N. Hansupalak, S. Srisuk, P. Wiroonpochit, Y. Chisti, Ind. Eng. Chem. Res. 2016, 55, 3974. [5] P. Wiroonpochit, K. Uttra, K. Jantawatchai, N. Hansupalak, Y. Chisti, Ind. Eng. Chem. Res. 2017, 56, 25, 7217–7223 [6] P. Wiroonpochit, S. Keawmaungkom, Y. Chisti, N. Hansupalak, Polym. Adv. Technol. 2022;1– 15. 68 RETA-IC 2023

AP - Poster Novel Chloroprene Rubber Emulsion for Manufacturing Medical Gloves with Reduced Risk of Hypersensitivity Mousumi De Sarkar1 1Denka Corporation, Louisiana Office, LaPlace, LA, USA Email: [email protected] Abstract Rubber additives, particularly vulcanization accelerators, are known to cause glove-related occupational contact dermatitis 1, 2. However, accelerators are still used in most of the synthetic rubber-based formulations during the manufacturing of medical gloves to provide the required performances in the final products. The new chloroprene rubber (CR) emulsion can be adequately crosslinked without an accelerator or sulfur, thereby minimizing the risk of adversary influence of rubber chemicals. Medical gloves produced using the new CR emulsion in an accelerator- and sulfur-free formulation conforms to the physical property requirements and the permeability resistance towards standard chemicals as per the industry standards. The new chloroprene rubber emulsion also offers intriguing possibilities to produce accelerator-free medical gloves with an extended choice of manufacturability in terms of curing temperature and time. The gloves conforming to ASTM specifications for medical gloves can be manufactured with the new CR emulsion at lower vulcanization temperatures (Figure-1) and/or at shorter vulcanization time than the conventional, leading to the possibility of reducing manufacturing costs and improving cycle time. Figure 1: Effect of Cure Condition on Tensile Strength of Gloves with Thickness 0.2-0.22 mm from New CR-based Formulation without Vulcanization Accelerator or Sulfur. [Aging Condition: 70 oC for 166 hrs] References [1] A. Heese, J. Hintzenstern, K. Peters, H. Koch and O. Hornstein, \"Allergic and irritant reactions to rubber gloves in medical health services,\" J Am Acad Dermatol, 1991, vol. 25, pp. 831-839 [2] H. Chen, C. Sun and M. Tseng, \"Type IV hypersensitivity from rubber chemicals: A 15-year experience in Taiwan,\" Dermatology, 2004, vol. 208, no. 4, pp. 319-325. RETA-IC 2023 69

AP - Poster 3D Printing of Conductive and Stretchable Double Network Hydrogel for Strain Sensor Karl Albright Tiston1, Voravee P. Hoven2, Benjaporn Narupai2 1Green Chemistry and Sustainability Program, Department of Chemistry, Faculty of Science, Chulalongkorn University, Thailand 2Department of Chemistry, Faculty of Science, Chulalongkorn University, Thailand email: [email protected], [email protected] Abstract Double network (DN) hydrogels having superior mechanical properties such as toughness and stretchability as compared to often fragile single network hydrogels are preferred for their practical applications.1 Such applications include gel-based devices like cell culture scaffold, wound healing, flexible wearable electronics and strain sensors.1,2 However, the development of DN hydrogels into these devices is restricted by the traditional casting or mold techniques for fabrication.3 Alternatively, hydrogels are suitable candidates for 3D printing, specifically direct ink writing due to their potential shear-thinning behavior.1,3 Here, we report a simple preparation of a 3D printable conductive and stretchable DN hydrogel comprising of kappa-carrageenan (k-CG) with a physically crosslinked network, and poly(acrylamide)-co-poly(hydroxyethyl acrylate) (PAAm-co-PHEA) chemically crosslinked with micellar crosslinker, Pluronic F127-bisurethane methacrylate (F127BUM). The thermoreversible sol-gel behavior of pre-gel solution allowed the printability of DN hydrogel formulation for the fabrication of complex 3D shapes and structures which can accommodate particular device specifications. The k- CG/PAAm/F127BUM hydrogel showed transparency, excellent stretchability, and elastic recovery. Furthermore, the hydrogel demonstrated strain sensing capability upon monitoring resistance, showing cyclic response and linear resistance change upon applied strain. The developed DN hydrogel is anticipated to be useful for further applications such as a smart material for motion sensing, electronic skin, health monitoring and diagnostics applications. Figure 1. Strain sensor fabrication workflow of k-CG/PAAm-co-PHEA/F127BUM DN hydrogel Acknowledgements This work is supported by Thailand Science Research and Innovation Fund (CU_FRB65_hea(64)_127_23_57)), and the ASEAN/Non-ASEAN Scholarship from Chulalongkorn University. References [1] Qiao, Z., et al. Design and Fabrication of Highly Stretchable and Tough Hydrogels. Polym. Rev. 2019, 60 (3), 420–441. [2] Yang, B, et al. Highly Stretchable and Transparent Double-Network Hydrogel Ionic Conductors as Flexible Thermal–Mechanical Dual Sensors and Electroluminescent Devices. ACS Appl. Mater. Interfaces. 2019, 11 (18), 16765–16775. [3] Liu, S.; Li, L. Ultrastretchable and Self-Healing Double-Network Hydrogel for 3D Printing and Strain Sensor. ACS App. Mater. Interfaces. 2017, 9 (31), 26429–26437. 70 RETA-IC 2023

AP - Poster Effect of polyethylene glycol On mechanical properties of nitrile gloves Pacharawan Siri1, Kanokwan Khongnil2, Kamonwan Khongnil2, Promsak Sa-nguanthammarong1, 1 National Metal and Materials Technology Center, National Science and Technology Development Agency, Thailand Science Park, Pathumthani 12120, Thailand 2 Rubber and Polymer Technology Program, Department of Chemistry, Faculty of Science, Ubon Ratchathani University, Ubon Ratchathani 34190, Thailand e-mail: [email protected] Abstract Nitrile gloves are made from carboxylated acrylonitrile butadiene latex, which has the advantages of good chemical resistance, high tensile strength, and no protein allergy risk. However, the elasticity, softness, comfort, and hand-fitting capability of nitrile gloves are not as good as those of natural rubber gloves. In order to improve these properties, the effect of a polar plasticizer, namely polyethylene glycol (PEG), on the tensile properties and elasticity of the nitrile gloves was investigated. In this study, PEG with different molecular weights (MW = 400, 1500, and 6000) was added to the latex at various contents (1, 3, 5, and 10 phr). The nitrile gloves were prepared by coagulant dipping and vulcanized in an oven at 80 C for 20 minutes prior to being tested. It was found that increasing PEG molecular weight resulted in reductions in elongation at break and tensile strength but had little effect on the modulus of the nitrile gloves. Regardless of the molecular weight, the 100% modulus, 300% modulus, and tensile strength decreased, while elongation at break increased with increasing PEG content. This may be explained by the plasticizing effect of PEG on rubber film. Based on the results, it can be concluded that PEG-400 can significantly improve the softness without a significant change in the tensile strength of the nitrile gloves. However, PEG cannot improve the elasticity of the nitrile gloves, as evidenced by the slight decrease in stress retention. Figure 1 Effect of type and amount of PEG on 100% and 300% Modulus of nitrile gloves References 1. Yew GY, Tham TC, Law CL, Chu DT, Ogino C, Show PL. Emerging crosslinking techniques for glove manufacturers with improved nitrile glove properties and reduced allergic risks. Materials Today Communications. 2019; 19: 39-50. 2. Tan KY, Phang SW, Phang CK, Lang Choh J, Pang Goh C, Ban Wong C, et al. Preliminary Study on Effect of Chemical Composition Alteration on Elastic Recovery and Stress Recovery of Nitrile Gloves. MATEC Web of Conferences. 2018; 152: 01011. 3. Liou DL, inventor; High Stress Retention Nitrile Glove. US Patent 2017/0099889 A1. 2017 Apr 13. RETA-IC 2023 71

ABSTRACTS MC Rubber Materials and Composites

MC New Engineered Elastomer Composite Products Expand the Potential for Performance & Sustainability of Rubber Products Joko Widjaya Cabot Corporation email: [email protected] Abstract In 2020, Cabot Corporation launched its first Engineered Elastomer Composite (E2C™) products, creating a new class of commercially available materials for use in tire & rubber products. Utilizing unique mixing technology, these products break conventional trade-offs in rubber compound design and performance and enable step-change improvements in performance and sustainability. This presentation will explain the product properties that enable performance gains in Tires and Industrial products. RETA-IC 2023 73

MC Natural Rubber for Carbon Dioxide Capture Krittaya Panploo1, Benjapon Chalermsinsuwan1, Sirilux Poompradub1,2 1 Department Chemical Technology, Chulalongkorn University, Praya Thai, Bangkok 10330, Thailand. 2 Center of Excellence in Green Materials for Industrial Application, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand. email: [email protected] Abstract The huge emission of greenhouse gases influences global warming which has received widely attention. Among the greenhouse gases, carbon dioxide (CO2) contributes to global warming because of its large emission amount from fossil fuels combustion, deforestation, and chemical processing. In this research, the significant challenge of CO2 capture and recent advantages of natural rubber (NR) to produce NR- based adsorbents are focused. NR is an important bio-renewable polymer and it shows the outstanding flexibility and elasticity and the excellent mechanical properties. To improve the CO2 adsorption performance, NR was filled with amine functionalized silica particles. The CO2 adsorption capacity of NR-based adsorbents was investigated using a stainless-steel reactor at ambient temperature and pressure. The regeneration of NR-based adsorbents was investigated by a combination of vacuum and temperature swing adsorption. Finally, the mechanism for CO2 adsorption of NR-based adsorbents was also proposed. Acknowledgements The authors gratefully acknowledge the funding support from the Thailand Research Fund (Grant No. RSA6180030), Chulalongkorn University and Malaysia-Thailand Joint Authority (MTJA), Research Cess Fund. References [1] K. Panploo, B. Chalermsinsuwan and S. Poompradub, RSC Adv. 2019, 9, 28916. [2] K. Panploo, B. Chalermsinsuwan and S. Poompradub, Chem. Eng. J. 2020, 402, 125332. 74 RETA-IC 2023

MC Toughness enhancement of PLA-based filaments for material extrusion 3D printing technique Siriwan Pongsathit1, Jutamas Kamaisoom1 Atikarn Rungteerabandit1, Pakorn Opaprakasit2, Krit Jiamjiroch3, Cattaleeya Pattamaprom1 1 Research Unit in Polymer Rheology and Processing, Department of Chemical Engineering, Faculty of Engineering, Thammasat University, Pathumthani 12120, Thailand. 2 School of Integrated Science and Innovation, Sirindhorn International Insitute of Technology, Thammasat University, Pathumthani 12120, Thailand. 3 Department of mechanical Engineering, Faculty of Engineering, Thammasat University, Pathumthani 12120, Thailand. email: [email protected] Abstract Poly(lactic acid) (PLA) is one of the most popular biodegradable thermoplastics in the market of 3D printing filaments used in material extrusion (ME) technique. This is because it is easy to print with low temperatures. However, its inherent brittleness limits its use in many applications. In this work, the toughness of PLA filament is improved by blending with various types of rubbers including natural rubber (NR), acrylic core-shell rubber (CSR), and thermoplastic polyurethane (TPU) in the amount of 15% by weight. It was found that PLA/TPU filament provided the smoothest surface with the best shape and dimension stability, while PLA/NR filament rendered the highest tensile toughness. For the effect of printing temperature, the highest printing temperature in this study (210 oC) provided the highest smoothness with the best shape stability and dimension accuracy. Interestingly, the tensile toughness and elongation at break of 3D printed specimens were found to be higher than those of compression molded specimens for all filament types. This could be explained by the ability of the 3D-printing technique in producing specimens which aligned in the printing direction in a fiber-like pattern. Acknowledgements The authors gratefully acknowledged the Ph.D. scholarship from the Faculty of Engineering, and the research unit funding from Thammasat University. References [1] Van den Eynde, M. & Van Puyvelde, P. (2017). 3D Printing of Polylactic Acid. Industrial Applications of Poly (lactic Acid). Springer: Cham, Switzerland, 139–158. [2] Shahrubudin, N., Chuan, L. T., & Ramlan, R. (2019). An Overview on 3D Printing Technology: Technological, Materials, and Applications. Procedia Manufacturing, 35, 1286-1296. [3] Redwood, B., Schöffer, F., & Garret, B. (2017). The 3D Printing Handbook: Technologies, Design and Applications. 3D Hubs B.V. [4] Gupta, B., Revagade, N., & Hilborn, J. G. (2007). Poly(lactic acid) fiber: An overview. Progress in Polymer Science, 32(4), 455-482. [ 5] Singhvi , M. , Zinjarde, S. , & Gokhale, D. ( 2019) . Polylactic acid: synthesis and biomedical applications. Journal of Applied Microbiology, 127(6). [ 6] Ou- Yang, Q. , Guo, B. , & Xu, J. ( 2018) . Preparation and Characterization of Poly( butylene succinate)/Polylactide Blends for Fused Deposition Modeling 3D Printing. American Chemical Society, 3(10), 2470-1343. RETA-IC 2023 75

MC [7] Prasong, W., Muanchan, P., Ishigami, A., Thumsorn, S., Kurose, T., & Ito, H. (2020). Properties of 3D Printable Poly(lactic acid)/Poly(butylene adipate-co-terephthalate) Blends and Nano Talc Composites. Journal of Nanomaterials. [8] Slapnik, J., Bobovnik, R., Mešl, M., & Bolka, S. (2016). Modified polylactide filaments for 3D printing with improved mechanical properties. Contemporary Materials, 2, 142-150. [9] Fekete, I., Ronkay, F., Lendvai, L. (2021). Highly toughened blends of poly(lactic acid) (PLA) and natural rubber (NR) for FDM-based 3D printing applications: The effect of composition and infill pattern. Polymer Testing. 99. [10] Phattarateera, S., & Pattamaprom, C. (2019). Comparative performance of functional rubbers on toughness and thermal property improvement of polylactic acid. Materials Today Communications, 19, 374-382. [11] Phattarateera, S., & Pattamaprom, C. (2019). The Viscosity Effect of Masticated Natural vs. Synthetic Isoprene Rubber on Toughening of Polylactic Acid. International Journal of Polymer Science. [12] Jia, S., Yu, D., Zhu, Y., Wang, Z., Chen, L., Fu, L. (2017). Morphology, Crystallization and Thermal Behaviors of PLA- Based Composites: Wonderful Effects of Hybrid GO/ PEG via Dynamic Impregnating. Polymers. [13] Hong, J. S., Kim, Y. K., Ahn, K. H., & Lee, S. (2008). Shear�induced migration of nanoclay during morphology evolution of PBT/PS blend. Journal of Applied Polymer Science, 108(1), 565-575. [14] Karamanlioglu, M., & Alkan, Ü. (2019). Influence of time and room temperature on mechanical and thermal degradation of PLA. Thermal Science, 23. Graphical Abstract PLA/Rubber compound Twinscrewextruder Filament 3Dprinter 3DprintingVsCompressionmolding 60 Compressionmolding 3Dprinting 50 Compressionmolding 3Dprinting 50 40 Tensile tSrength(MPa)40PLA/TPUPLA/CSR PLA/NR 30 PLA/NR TensileToughness(MPa)304 Compresionmolding 20 20 10 lEongationat Break(%)1030 0 Neat PLA PLA/TPU PLA/CSR Neat PLA 3Dprintng 2 1 0 Neat PLA PLA/TPU PLA/CSR PLA/NR 76 RETA-IC 2023

MC Study the influence of Nano sized Zinc Oxide (ZnO) Particles on the Properties of vulcanized Natural Rubber Latex Films Phattarawadee Nun-anan1, Jutarat Phanmai1, Sarit Thanomchat2, Ronnapa Phonthong2, Panisara Rattanapanyachot1 1 Chemical Innovation, Bangkok, Thailand, 10240 2 IRPC Public Company Limited, Rayong, Thailand, 21000 Email: [email protected] Abstract Nano-sized zinc oxide (ZnO) particles were synthesized through a mechano-chemical route and their effects on vulcanized natural rubber latex (NRL) properties were investigated. Nano-sized ZnO at different concentrations (i.e., 0.50, 0.10 and 0.05 phr) and conventional ZnO (or micro-sized ZnO) at 0.5 phr were added into the NRL, and the pre-vulcanized NR latex and vulcanized NR properties were compared with conventional ZnO on modified quick swelling index test, mechanical properties and crosslink density (i.e., swelling ratio). In compared to micro-sized ZnO filled NR sample, nano-sized ZnO filled NRL sample performed better curing index. Mechanical properties (i.e., tensile strength and elongation at break) and swelling behavior were found to be higher with less nano-sized ZnO concentrations (i.e., 0.10 and 0.05 phr) in the NRL films. As a result, it can be concluded that nano-sized ZnO can be used at less level than micro-sized ZnO which is beneficial in reducing residual heavy metal oxide (i.e., especially Zn content) and producing more eco-friendly material. This present study may be valuable in dipped products (i.e., glove and condom) that are concerned with the residual Zn in the finished products, following the near future trend of heavy metal reduction. Acknowledgements This work was supported by Chemical innovation Co., Ltd. Also, the support from the IRPC Public Company Limited. In addition, the research and development center is acknowledged for their technical supporting. RETA-IC 2023 77

MC - Poster Porosities and Mechanical Properties of Carbon Fiber Reinforced Plastics Produced by Vacuum-Bag-Only Technique Using Simple Electric Oven Pimpet Sratong-on1, Sutep Joy-A-Ka2, Sawanya Suwannawong1 1 Faculty of Engineering, Thai-Nichi Institute of Technology, Suanluang, Bangkok, 10250, Thailand. 2 Material Properties and Failure Analysis Laboratory, Thailand Institute of Scientific and Technological Research, Khlong Luang, Pathum Thani 12120, Thailand. email: [email protected] Abstract The curing process under pressure in autoclave ovens results in high-quality of carbon fiber-reinforced plastics (CFRPs) parts; however, the cost of an autoclave is not affordable for small-scale enterprises. Vacuum Bag Only (VBO) technique can produce the comparable mechanical properties of CFRP parts to an autoclave by using the electric oven. Nevertheless, the thermosetting plastic is recommended to cure with more than two ramps and isothermal holds leading to the necessity of a complicated controller system. Hence, this oven is hard to find as a commercial product. This study proposes the single-hold curing cycle for carbon fiber prepreg allowing specimens cured in a simple electric oven. The plain weave carbon fiber prepreg was fabricated in the stacking sequence of [0/90/0/90] with the size of 120 x 240 mm2. The specimens were divided into three groups; specimens with and without press at room temperature to reduce entrapped air in prepreg before curing and the specimen curing under a non- vacuum atmosphere. All of them were cured from room temperature to 120C and held for 50 mins followed by air cooling. The tensile test; ASTM D3039/3039M, was carried out and the porosities inside the non-vacuum specimen were observed by X-ray CT. In case of specimen cured under a non-vacuum atmosphere, the resin was unable to fulfill the cross junctions of fiber in Fig.1 (a) and the porosities were also clearly observed in Fig.1(b). Accordingly, this specimen produced the lowest ultimate strength (Fig.1(c)) due to the defects. Figure 1. (a-b) Three-dimensional and side view of X-ray CT image of carbon fiber/ epoxy plastic fabricated under non-vacuum atmosphere and c) The tensile test results of specimens with, without press before curing and cured under non-vacuum atmosphere compared with finite element analysis 78 RETA-IC 2023

MC - Poster Acknowledgements This project was supported by Thai-Nichi Institute of Technology (project 2102/A004) and Takahashi Industrial and Economics Research Foundation for the fiscal year 2021-2022. The authors are grateful to Mr.Praprut Prommachat for technical support References [1] S. Park, C. Choi, W. Choi et al., Appl. Compos. Mater. 2019, 26(1), 187-204. [2] L. Liu, B. Zhang, D. Wang, Z. Wu, Compos. Struct. 2006, 73(3), 303-309. [3] T. Centea, P. Hubert, Compos. Sci. Technol. 2011, 71, 593-599. [4] D. Hyun, D. Kim, J. Shin et al., J. Compos. Mater. 2021, 55(8), 1039-1051. RETA-IC 2023 79

MC - Poster Towards non-toxic and eco-friendly truck tires through the use of bio-oils as an alternative process oil Chesidi Hayichelaeh1, Kanoktip Boonkerd1,2 1 Department of Materials Science, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Bangkok 10330, Thailand. 2 Center of Excellence in Green Materials for Industrial Application, 254 Phayathai Road, Bangkok 10330, Thailand. email: [email protected] Abstract Rubber process oil (RPO) is a crucial ingredient for rubber compounds to provide an easy processibility and improve filler dispersion within rubber matrix that leads to balance overall properties of rubber products especially for truck tires due to its requirement in high filler loadings. Aromatic oil, namely distillate aromatic extract (DAE) oil, is a right choice for rubber compounds of truck tires because of the good compatibility between oil and rubber. Since an introduction of a toxicity of DAE that contains polycyclic aromatic hydrocarbons as a carcinogen, bio-oil being non-toxic, eco-friendly, renewable, and sustainable products has been focused as an alternative to DAE. The properties of carbon black-filled natural rubber compounds containing bio-oil, i.e., palm oil, were investigated. It was found that the use of bio-oil resulted in similar levels of filler-filler interactions, but high filler-rubber interactions when compared to the one with DAE [1]. In addition, the presence of bio-oil in rubber compounds promoted low tan δ at 60oC as referred to low rolling resistance, leading to safe-energy tires [1]. On the other hand, the use of bio-oil encounters inferior mechanical properties as affected the low levels of crosslink density of the rubber compounds because the unsaturated structures in oil molecules can consume the sulfur atom [1, 2, 3]. An improvement on mechanical properties of rubber compound containing bio-oil can be carried out by adjustment of the sulfur contents. So, the effect of sulfur contents on the properties of rubber compounds containing bio-oil will be discussed in this presentation. Figure 1. Graphical abstract Acknowledgements The authors acknowledge the financial support from the Ratchadapisek Somphot Fund for Postdoctoral Fellowship, Chulalongkorn University, and the GAICCE Research Grant from ASEAN University Network/Southeast Asia Engineering Education Development Network (AUN/SEED-Net). References [1] C. Hayichelaeh and K. Boonkerd, Ind. Crops Prod. 2023, 194, 116270. [2] C. Hayichelaeh, P. Nun-Anan, M. Purbaya and K. Boonkerd, Polymers. 2022, 14, 2479. [3] C. Hayichelaeh, K. Boonkerd, P. Nun-Anan, and M. Purbaya, Polym. Adv. Technol. 2022, 33, 303. 80 RETA-IC 2023

MC - Poster Preparation and Characterization of Natural Rubber/Acrylonitrile Butadiene Rubber-Based Composites with Bio-Hydroxyapatite Namthip Bureewong1,2, Preeyaporn Injorhor1,2, Thanapoom Aphidat1,2, Thikamporn Peanchob1,2, Kittima Buapang1,2, Chaiwat Ruksakulpiwat1,2, Yupaporn Ruksakulpiwat1,2 1 School of Polymer Engineering, Institute of Engineering, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand. 2 Research Center for Biocomposite Materials for Medical Industry and Agricultural and Food Industry, Nakhon Ratchasima 30000, Thailand. email: [email protected], [email protected] Abstract Natural rubber (NR)/acrylonitrile butadiene rubber (NBR)-based composites bio-hydroxyapatite BHAp) derived from seabass scales were prepared by using an internal mixer before molding by compression. The BHAp in the range of nano-scale was prepared by treating seabass scales with acid and alkali solution using an autoclave. The BHAp was used as filler in NR/NBR-based composites. Cure characteristics of the rubber composites were investigated by a moving die rheometer. Mechanical properties of the rubber composites such as tensile strength, modulus, tear strength, and hardness were investigated. Moreover, commercial silica (CSiO2) was added to compare the rubber composites' properties. 70NR/30NBR blend showed the highest tensile strength and elongation at break at 15.45±0.26 MPa and 739.19±3.29(%), respectively. 70NR/30NBR/10BHAp/10CSiO2 showed the highest modulus at 200% elongation. Furthermore, it also showed the highest tear strength and hardness compared with other polymer blends and their composites. These rubber composites containing bio- filler were expected to have potential in medical devices. Acknowledgements The authors are grateful to Suranaree University of Technology (SUT), Thailand Science Research and Innovation (TSRI), to the National Science, Research and Innovation Fund (NSRF), and to the Research Center for Biocomposite Materials for the Medical Industry and Agricultural and Food Industry for the financial support. RETA-IC 2023 81

MC - Poster Effect of Fish scales on mechanical properties of grafted natural rubber Natthawadee Jiamkosit1, Yupaporn Ruksakulpiwat1,2, Chaiwat Ruksakulpiwat1,2 1 School of Polymer Engineering, Institute of Engineering, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand. 2 Research Center for Biocomposite Materials for Medical Industry and Agricultural and Food Industry, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand. email: [email protected] Abstract This research studied the effect of Fish scales on the mechanical properties of grafted natural rubber latex (NR) by a Copolymer of Methacrylic acid (MAA) and Glycidyl methacrylate (GMA). Fish scales particle were prepared by Alkali heat treatment. The NR graft MAA-co-GMA (NR-g-MAA/GMA) was then mixed with Fish scales (FS) and silica (Si) to prepare NR-g-MAA/GMA /10 FS composites and NR- g-MAA/GMA /5 FS/5 Si composites. The mechanical properties of polymer composites including tensile strength, and tear strength were investigated by a Universal testing machine ( UTM) . The NR- g- MAA/GMA /10 FS composites gave tensile strength of 20.76 ± 1.51 MPa and Tear strength of 31.4 kN/m which were higher than NR-g-MAA/GMA /5 FS/5 Si composites. Acknowledgments The authors are grateful to Suranaree University of Technology (SUT), Thailand Science Research and Innovation (TSRI), the National Science, Research and Innovation Fund (NSRF), and to the Research Center for Biocomposite Materials for the Medical Industry and Agricultural and Food Industry for the financial support. References [1]. Thuong Nghiem Thi, Ha cao Hong, Yusof Nurul Hayati and Seiichi Kawahara. (2021). Graft copolymerization of methyl methacrylate and vinyltriethoxysilane binary monomers onto natural rubber. Polymer Research,28:246 [2]. Sathiskumar, S.; Vanaraj, S.; Sabarinathan, D.; Bharath, S.; Sivarasan, G.; Arulmani, S.; Ponnusamy, V.K. Green synthesis of biocompatible nanostructured hydroxyapatite from Cirrhinus mrigala fish scale—A biowaste to biomaterial. Ceram. Int. 2019, 45, 7804–7810. 82 RETA-IC 2023

MC - Poster Effect of Filler Content on properties of poly (methacrylic acid-co-N- (hydroxymethyl)acrylamide)-grafted deproteinized natural rubber Pichaya Rumjuan1,2, Pranee Chumsamrong1,2, Chaiwat Ruksakulpiwat1,2* and Yupaporn Ruksakulpiwat1,2* 1School of Material Engineering, Institute of Engineering, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand 2Research Center for Biocomposite Materials for Medical Industry and Agricultural and Food Industry, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand *e-mail: [email protected], [email protected] Abstract The goal of this study is to compare how well nano calcium carbonate and silica work as reinforcing agents in natural rubber. In this study, poly (methacrylic acid-co-N-(hydroxymethyl) acrylamide)- grafted deproteinized natural rubber (P(MAA-co-NHMA)-g-DPNR) was prepared and used as a compatibilizer of the silica (SiO2) and nano-calcium carbonate (Nano-CaCO3) composites. The grafting was used to compatibilized SiO2 and Nano-CaCO3 filler in composites. The P(MAA-co- NHMA)-g-DPNR was prepared by emulsion graft copolymerization of methacrylic acid (MAA) and N- ( hydroxymethyl) acrylamide ( NHMA) using cumene hydroperoxide ( CHPO) and tetraethylene pentamine (TEPA) as redox initiators. The weight ratio of MAA and NHMA was kept constant at 1. The (P(MAA-co-NHMA)-g-DPNR) was then mixed with filler are SiO2 and Nano-CaCO3 by the internal mixer to prepare composites. The effect of P(MAA-co-NHMA)-g- DPNR contents on the mechanical properties of composites was investigated. The amount of filler changed from 0 to 20 phr during the blending process. A moving die rheometer (MDR) was used to analyze the cure properties. The graft copolymerization was studied by scanning electron microscopy (SEM). The bound rubber of compounds and the mechanical properties were measured. Both filler kinds have the same effects on the processing characteristics of rubber, according to studies. That means, adding more filler will require more energy to mix and will likely cause the viscosity of the rubber compound to continue rise. Additionally, it was found that increasing the amount of filler of the scorching time (tS1) and the optimum cure time (tC90) resulted in a shortening. However, the mechanical qualities of the rubber will increase as the filler content rises. From the results of the study, it was found that the rubber compound formulated with 15 phr calcium carbonate and 5 phr silica had a tensile strength of 21.9 MPa, an elongation of 742% , and a hardness of 38. 34 IRHD, respectively, which had the best mechanical properties of all formulations and compared with general rubber compound formulations, gave better results. This is consistent with the results of the SEM experiment, showing that the distribution of the filler is uniform. References [1] Arayapranee, W., & Rempel, G. L. (2013). Effects of polarity on the filler-rubber interaction and properties of silica filled grafted natural rubber composites. (n.d.). Journal of Polymers, 2013. [2] Borapak, W., Chueangchayaphan, N., Pichaiyut, S., & Chueangchayaphan, W. (2021). Cure characteristics and physico-mechanical properties of natural rubber/silica composites: Effect of natural rubber-graft-poly (2-hydroxyethyl acrylate) content. Polymer Bulletin, 78, 2009-2023. [ 3] Hewitt, N. ( 2007) . Compounding precipitated silica in elastomers: theory and practice. William Andrew. RETA-IC 2023 83

MC - Poster Effect of Stereocomplexation by Using PDLA on Heat Resistance of PLA/NR Blends Pongsakorn Malayarom1, Cattaleeya Pattamaprom2 1,2 Department of Chemical Engineering, Faculty of Engineering, Thammasat University, Patumthaini, Thailand email: [email protected] Abstract This research investigated the effect of natural rubber (NR) and poly-D-lactic acid (PDLA) on the improvement of thermal and impact properties of Poly-L-lactic acid (PLLA or PLA). The NR content was fixed at 15 wt% and the PDLA content was varied from 5 to 42.5 wt%. It was found that the incorporation of well-dispersed NR in PLA led to a significant improvement in both thermal resistance and impact strength of PLA as NR contributed to faster crystallization and higher %crystallinity of PLA. With the addition of various PDLA contents into PLA/NR blends, it was found that the higher PDLA content could provide higher %crystallinity and crystallization rate of stereocomplex crystals. The higher percentage of stereocomplex crystals (%Xc,sc) was strongly correlated with the increase in heat resistance of the blends. In terms of impact strength, the PDLA content that could provide the highest impact strength among all stereocomplex blends was 10 wt%. At PDLA content of 30 and 42.5 wt%, the blends could tolerate 100 ⁰C for more than 1 day. Acknowledgements Firstly, the authors acknowledge the financial support by Faculty of Engineering, Thammasat University. Secondly, without them this thesis would have took a longer time to complete, I am grateful to staffs at the National Metal and Materials Technology Center (MTEC) who helped and supported in cut into a pellet of NR form by rubber extruder pelletizer. Lastly, I am also thanks to all colleagues at my laboratory office for cheering and helping as much as they could for this research. 84 RETA-IC 2023

MC - Poster Design and fabrication of thermal neutron shielding materials based on natural rubber and boron carbide Jittinun Saenpoowa1, Chaiwat Ruksakulpiwat2,3, Chinorat Kobdaj1,4,5 1 School of Physics, Institute of Science, Suranaree University of Technology, Muang Nakhon Ratchasima 30000, Thailand. 2 School of Material Engineering, Institute of Engineering, Suranaree University of Technology, Muang Nakhon Ratchasima 30000, Thailand. 3 Research Center for Biocomposite Materials for Medical Industry and Agricultural and Food Industry, Suranaree University of Technology, Muang Nakhon Ratchasima 30000, Thailand. 4 Boron Neutron Capture Therapy Research Center, Suranaree University of Technology, Muang Nakhon Ratchasima 30000, Thailand. 5 Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400, Thailand email: [email protected] Abstract The thermal neutron shielding materials based on natural rubber were fabricated in ten different formulas with boron carbide (B4C) contents of 0, 20, 40, 60, and 139.6 parts per hundred rubbers (phr). Furthermore, formulas with varying rubber base types, such as natural rubber (NR), epoxidized natural rubber (ENR), and a NR/ENR blend, are considered. Additionally, the difference in carbon black contents of 30 and 60 phr in natural rubber-based materials is compared. Two other formulas that differ in the contents of a primary accelerator, N-cyclohexylbenzothiazole-2-sulfenamide (CBS) at 0.5 and 1 phr in a natural rubber base, are also analyzed. And in the last formula, dicumyl peroxide (DCP) was used as both a vulcanization and activation agent. In this work, all shielding formulas were studied for their effect on mechanical and neutron shielding properties. The increase in carbon back at 60 phr resulted in a Shore hardness degree of 76.53, a specific gravity of 1.30, and an activation energy of 120.56 kJ/mol. An increase in CBS at 1 phr gave rise to a minimum cure time of 2.07 minutes, whereas using DCP had the longest curing time of 5.17 minutes. Neutron imaging was used to determine and compare the efficiency of different formulas. Each sample is 6 millimeters thick. We found that B4C at 139.6 phr has the best thermal neutron shielding among all our samples, with the lowest level of a 0.045 brightness fraction. Acknowledgments This work was financially supported by the Thailand Center of Excellence in Physics (Contract No.ThEP-61-PHM-SUT4), Suranaree University of Technology (SUT), Thailand Science Research and Innovation (Contract No. IRN62W0006), National Science, Research and Innovation Fund (Grant No.FF1-105-65-36-01) and the Boron Neutron Capture Therapy Research Center (BNCT). In addition, the authors would like to thank the Thailand Institute of Nuclear Technology for courtesy for the thermal neutron shielding experiment. Moreover, colleagues in the high-energy particle physics group and the polymer lab group, SUT provided fruitful discussions and advice to improve this work. References [1] C. Jumpee, T. Rattanaplome and N. Kumwang, IOP Conf. Ser.: Mater. Sci. Eng. 2020 773 012036 [2] J. Saenpoowa, C. Ruksakulpiwat, C. Yenchai, C. Kobdaj, J. Phys.: Conf. Ser. 2023 2431 012079 RETA-IC 2023 85

MC - Poster Mechanical Properties and Cure Characteristics of Nanocellulose/Natural Rubber Composites: Effects of Surface Treatment and Filler Content Usasawan Plengnok1, Kasama Jarukumjorn2 1 School of Polymer Engineering, Institute of Engineering, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand. 2 Center of Excellence on Petrochemical and Materials Technology, Chulalongkorn University, Bangkok 10330, Thailand. email: [email protected] Abstract Nanocellulose (NC) prepared from sugarcane bagasse (SCB) and Si-69 treated NC were used as reinforcing fillers in natural rubber (NR). The average particle size of NC was 39.15 nm. NC and Si-69 treated NC contents were 0, 2.5, 5.0 and 10 phr. NR composites were prepared using a two-step process including preparation of a masterbatch by mixing NC and Si-69 treated NC in NR latex and then compounding the masterbatch with solid NR and other chemicals by a two roll mill. With increasing NC and Si-69 treated NC content, tensile strength and modulus at 300% elongation of NR composites increased whereas elongation at break decreased. Mechanical properties of Si-69 treated NC/NR composites were higher than NC/NR composites. Increasing NC content resulted in the reduction of scorch time and cure time of the composites but the improvement of maximum torque (MH) and minimum torque (ML). Silane treatment showed insignificant effect on the scorch time, cure time, MH and ML of the composites. Acknowledgements 1. School of Polymer Engineering, Institute of Engineering, Suranaree University of Technology 2. Center of Excellence on Petrochemical and Materials Technology, Chulalongkorn University 86 RETA-IC 2023