Synthesis of Poly(D-Lactic Acid) Using a 2-Steps Direct Polycondensation Process

AbstractA two steps direct polycondensation process of poly(D-lactic acid) (PDLA) synthesis was studied. The melt- polymerization was combined with esterification using p-Toluenesulfonic acid without addition of metal catalyst. The pre-polymer product from the first step was subsequently subjected to solid-state polymerization (SSP) under high temperature and reduced pressure. Prior to the SSP process, the pre-polymer was characterized its thermal property to detect the crystallization temperature (Tc). The pre-polymers were annealed at temperature Tc for 2h until the crystallization peak disappeared. The SSP of pre-polymers was carried out for 30h to produce the satisfied thermal property and high molecular weight. The synthesized poly(D-lactic acid) showed melting temperature of 177oC, weight average molecular weight of 33,300Da, and decomposition temperature of 255oC

Impact Property of Flexible Epoxy Treated Natural Fiber Reinforced PLA Composites

AbstractThe modification is required for more practical applications due to the brittleness of PLA polymer. The improvement of the impact properties of PLA is an addition of fillers or reinforcements. Bamboo fiber, vetiver grass fiber and coconut fiber were used as alternative reinforcements in PLA composites. Injection molded of untreated and flexible epoxy treated composites at various reinforcement content was prepared. The impact strength of natural fiber reinforced PLA composite decreased with the increased of fiber content. The maximum reduction in impact strength was 23.8, 27.3 and 56.2% for bamboo fiber/PLA, vetiver grass fiber/PLA and coconut fiber/PLA composites, respectively. The flexible epoxy surface treatment improved impact property of bamboo fiber/PLA and coconut fiber/PLA composites when compared against the untreated composites. Unlike the other combinations, treated vetiver grass fiber/PLA composite showed less improvement in impact strength when compared with other natural fibers. Bamboo fiber proved to be the most effective reinforcement among all studied reinforcements

Effect of Additive on Crystallization and Mechanical Properties of Polymer Blends of Poly(Lactic Acid) and Poly[(Butylene Succinate)-co-Adipate]

AbstractThe effect of additive on crystallization and mechanical properties of poly(lactic acid) (PLA) and poly(butylene succinate-co-adipate) (PBSA) blend was studied. PLA and PBSA were blended in a twin screw extruder, which incorporated poly(butylene adipate-co-terephthalate) (PBAT) as an additive in PLA/PBSA blend. The ratio of PLA/PBSA was 80/20. The contents of PBAT were varied from 0 to 50 wt%. The thermal properties and crystallization behavior of PLA/PBSA/PBAT blends were analyzed by differential scanning calorimetry. The effect of PBAT contents on non-isothermal crystallization kinetic of the composites was investigated by using Avrami equation. Tensile strength and impact performance of the PLA/PBSA/PBAT blends decreased when increasing PBAT contents. It can be noted that the addition of 20 wt% PBAT showed the maximum impact performance of the PLA/PBSA blends

Effect of Compatibilizer on PLA/PP Blend for Injection Molding

AbstractPolymer blends of poly(lactic acid) and polypropylene were prepared for the application to injection molding products. Due to the phase separation of PLA and PP, the addition of polypropylene-graft-maleic anhydride (PP-g-MAH) as a compatibilizer was studied. The polymer blends were comprised of PLA:PP ratios 80:20 and 20:80 with addition of 1, 3 and 5 wt% of PP-g-MAH. The product samples were processed dry blend with injection molding process and the products were subjected to thermal, mechanical properties and morphology analysis. The thermal analysis confirmed that addition of PP-g-MAH has no effect on crystalline melting temperature of the polymer components as well as no effect on the mechanical properties. The morphology study of the polymer blends confirmed the adhesion of PLA and PP by assistance of PP-g-MAH. The addition of more amount of PP-g-MAH resulted in high polarity of a compatibilizer and decreased the compatibility with PLA. The tensile strength of polymer blends increased with increasing amounts of PLA. The research results confirmed the application of polymer blend system to injection molding process

Preparation of Biodegradable Polymer Copolyesteramides from L-Lactic Acid Oligomers and Polyamide Monomers

AbstractBiodegradable copolyesteramide was synthesized from L-lactic acid oligomers and polyamide monomers to improve the properties of poly(lactic acid). The oligomer was synthesized from L-lactic acid using direct polycondensation process at 170 oC, 30 torr for 7h. p-Toluenesulfonic acid used as a catalyst. From 1H NMR analysis the oligomers have degree of polymerization of ca. 5. The L-lactic acid oligomer (OLLA) was subjected to reacted with ɛ-caprolactam (CLM) with different ratios: 90:10, 80:20, 70:30 and 60:40 using SnCl2·2H2O as a catalyst at 130, 150 and 170 oC pressure 30 torr for 3h. The synthesized polymers were subjected to thermal property analysis using DSC technique and analyzed the functional groups with FT-IR. It was found that the melting temperature of the polymers increased with increasing amounts of CLM but decreased when the amount of CLM exceeded 30 percent. FT-IR analysis confirmed structure of copolyesteramide comprised of amide ide units and lactate unit