Characterization and biodegradation of poly (vinyl alcohol)/cassava starch

Abstract

A series of poly (vinyl alcohol)/cassava starch (PVA/CS) blends at 50, 60, 70 and 80 wt.% cassava starch contents were prepared in one-step compounding process. One step compounding means, all blends were compound together without solely plasticized PVA or cassava starch at beginning. All blends were characterized and testing accordingly. In this research, comparison between one-step compounding and two-step compounding (plasticized PVA/CS at the beginning) were tested by tensile strength. It shows that their tensile strengths were comparatively higher than the two-step compounding process of PVA/CS blends. In term of impact test, it indicates that CS acts as non-reinforcing filler. The compatibility of PVA/CS represents the similarity functional group and possess same polar group. Studies on thermal stability and crystallinity shows, increasing the cassava starch loading in PVA matrix, has reduced the enthalpy of melting point as well as degree of crystallinity. The onset degradation had shifted to a higher temperature when a higher percentage of cassava starch was used in PVA matrix. This is due to cyclic hemiacetal had been introduced into PVA blend by cassava starch. It resist to thermal attack. In biodegradability test, several factors have been determined to evaluate the rate of biodegradation. Increase the humidity as well as increasing the cassava starch loading in PVA matrix will improve the susceptibility contact of microorganism onto the surface of PVA/CS blend. Aspergillus Oryzae had been selected as a good reagent used to degrade the sample of PVA/CS blend compared to Bacillus Amyloliquefaciens and effective microorganism. The biodegradation process of PVA/CS blends in anaerobic condition is much more faster compared to aerobic conditions.