Papers by Author: Chaiwat Ruksakulpiwat

Abstract: In this study, effect of PBS content on physical properties of polylactic acid (PLA) and polybutylene succinate (PBS) blends was studied. The content of PBS was varied from 0 30 %wt. The blends were mixed using an internal mixer. The samples were prepared using a compression molding. It was shown that tensile strength and Youngs modulus of PLA/PBS blends were decreased with increasing PBS content from to 0 30 %wt. Nevertheless, elongation at break and impact strength of the blend were increased with increasing the amount of PBS up to 20 %wt. Polylactic acid grafted glycidyl methacrylate (PLA-g-GMA) was used as the compatibilizer in PLA/PBS/PLA-g-GMA blends. PLA-g-GMA was shown to improve interfacial adhesion between PLA and PBS. With the addition of PLA-g-GMA, mechanical properties of PLA/PBS blend were improved. The preparation of cassava pulp (CP) to be used as filler in PLA/PBS blends and PLA/PBS/PLA-g-GMA blends was studied. Effect of CP content on mechanical properties CP/PLA/PBS composites was studied. PLA-g-GMA was also used as compatibilizer in CP/PLA/PBS composites. The mechanical properties of CP/PLA/PBS composites were improved with the addition of PLA-g-GMA as well.

Abstract: Cassava pulp (CP) is an inexpensive and broadly available waste by-product from cassava starch production. This by-product is basically constituted of cellulose fiber and residual starch. In this study, cassava pulp was mixed with natural rubber (NR) with various contents using two roll mills to obtain CP/NR composites. Natural rubber grafted glycidyl methacrylate (NR-g-GMA) was used as compatibilizer in CP/NR/NR-g-GMA composites. Sulfur conventional vulcanization was used. The composite specimens were prepared by compression molding. Mechanical properties and morphological properties of composites were investigated. The results showed that tensile strength was significantly increased with increasing content of cassava pulp up to 20 phr. However, when cassava pulp was increased more than 30 phr, tensile strength was slightly decreased. Elongation at break of NR composites was not changed with increasing cassava pulp. The modulus of NR composites was increased with increasing cassava pulp content. Morphological properties of CP/NR composites was elucidated as well.

Abstract: This research shows a great potential of cogon grass fiber to be used as a reinforcement in epoxidized natural rubber composites. The thermal and mechanical properties of cogon grass fiber-epoxidized natural rubber composites were studied. The chemical treatment of cogon grass fiber to be used as a reinforcing filler was revealed. Effects of fiber treatment method and treatment time of cogon grass fiber on thermal properties of the fibers and their composites were elucidated. The addition of cogon grass fiber into epoxidized natural rubber (ENR) improved the mechanical properties of the composites.The result indicated that alkaline treatment followed by acid treatment of cogon grass fiber led to an increase in thermal decomposition temperature and mechanical properties of the composites more than that without acid treatment. With increasing the amount of fiber, tensile strength of ENR composites were significantly increased while elongation at break was insignificantly changed. ENR with the addition of 4-Amino-6-hydroxy-2-mercaptopyrimidine monohydrate as coupling agent (ENRC) was shown to have higher tensile strength, modulus at 200% elongation and elongation at break than ENR. Improved mechanical properties were also obtained in ENRC composites compared to those of ENR composites.

Abstract: From our previous study, natural rubber (NR) was used to improve toughness of poly (lactic acid) (PLA). Impact strength and elongation at break of PLA was increased when adding NR. Moreover, by using NR-g-GMA as compatibilizer for PLA and NR blend, impact strength and elongation at break was improved. However, tensile strength and modulus of PLA/NR blend with and without NR-g-GMA were decreased. In this study, calcium carbonate (CaCO₃) and vetiver grass fiber were used as fillers in PLA/NR blend. With the addition of CaCO₃ into PLA/NR blend with NR-g-GMA, impact strength and modulus of the composite were further increased with a loss in tensile strength. In contrast, the addition of vetiver grass fiber into PLA/NR blend with NR-g-GMA led to an increase in tensile strength and modulus and a decrease in impact strength and elongation at break. The onset degradation temperatures of PLA composites were lower than that of PLA and PLA/NR blend.

Abstract: Polylactic acid (PLA) and natural rubber (NR) were melt blended with vetiver grass fiber using an internal mixer. Heat treatment at the temperature of 180°C was done to obtain heat treated vetiver grass fiber. Glycidyl methacrylate grafted natural rubber (NR-g-GMA) was used as a compatibilizer of PLA/vetiver/NR composites. The injection molding and compression molding were used to prepare the specimens. Molecular weight determination of PLA before and after processing was done by Gel Permeable Chromatography (GPC).Comparisons between the mechanical properties of the composites prepared from injection molding and compression molding were made.

Abstract: The blend membranes from PAA and NR-graft-PVA were prepared. By introducing potassium persulfate (KPS) initiator, PVA can be chemically attached to the NR latex particles which was confirmed by FT-IR spectroscopy. Most of added-PVA was grafted on the NR latex particles as indicated by the almost-linear increasing of grafting percentage. The swelling of the PAA/NR-g-PVA blend membranes was performed in different concentrations of water-ethanol solutions. For the water concentration lesser than 30 vol.%, all membranes showed almost no-swelling but beyond 30 vol.% water, the degree of swelling revealed the substantial swelling with the degree of swelling increased as PAA content in the membrane increased.

Abstract: The purpose of this research is to modify natural rubber (NR). The optimum conditions for synthesis of epoxidized natural rubber (ENR) was investigated. The synthesized ENR was modified by hydrogenation reaction. This modified ENR was called HENR. The optimum amount of CuSO4 ·5H2O used in this reaction was investigated. It was found that the optimum condition for synthesizing ENR is as followed. The type of surfactant is POE(12)tridecyl ether and the amount of this surfactant is 5 phr. The highest epoxide content which received from fresh NR latex and concentrated NR latex in selected condition are 25.53 and 22.51% respectively. The highest percentage of hydrogenation from this condition is 67.90%. It can be concluded that after hydrogenation reaction HENR shows higher thermal resistance than that of synthesized ENR.