Effect of Different Plasticizers on Tensile Properties of PVA/Sago Starch System Before and After Weathering Exposure

In this research, the effect two different sets of natural based plasticizers in polyvinyl alcohol (PVA)/sago starch system was evaluated. The natural based plasticizers used are epoxidised soybean oil (ESO) and sorbitol. The PVA, starch and plasticizer underwent a compounding process without plasticisers with a fixed amount of 20% plasticisers and two different ratios of PVA and Sago Starch (SS) using the twin screw extruder. The plasticized samples were exposed to the outdoor environment for two weeks according to ASTM D1435 test method and the tensile properties (tensile strength, elongation at break and tensile modulus) before and after exposure samples were studied according to ASTM D882. Scanning electron microscope (SEM) was conducted to determine the morphological effect on each blend with different plasticizers loading. Results showed that PVA/sago starch plasticized with ESO before and after exposure to the environment for two weeks gives higher tensile strength, elongation at break and tensile modulus compared to PVA/sago starch plasticized with sorbitol. SEM fractography showed PVA/sago starch plasticized with ESO shows better compatibility and dispersion. Better compatibility and dispersion between ESO and PVA/sago starch system support the evidence that the tensile properties improved due to better dispersion and compatibility in the system.