Polypropylene and corn starch biocomposites: Investigation the biodegradability in fungal culture medium

Every day thousands tons of plastic waste are entering the world's environment, so it will cause pollution problems in the environment. To overcome these problems, we should to use biodegradable plastics. Researchers have shown that starch-based materials are biodegradable. Biodegradation is nature's way of recycling wastes or breaking down organic materials into nutrients, when microorganisms use these as a source of carbon and energy. In this study, biodegradable blends of polypropylene/thermoplastic starch (PP/TPS) with different content of TPS (100/0, 90/10, 70/30, 50/50), in presence of 6 wt% Ethylene Vinyl Acetate (EVA) copolymer as a coupling agent, were prepared using co-rotating twin screw extruder. Biodegradation of blends were done in fungal culture medium and were assessed by SEM images, monitoring the structural changes in the FT-IR spectra and weight loss of specimens after 3 weeks culturing. SEM images revealed that with increasing starch content more holes found on the surface of specimens after biodegradation. In the FTIR spectra, decreasing in intensity of hydroxyl regions after biodegradation indicates that starch domains of blends have eroded by fungi. The biodegradation was also monitored by the increase in the carbonyl index. Increasing in starch content helped to speed up the weight loss of PP/TPS blends.

Keywords:

Biocomposite , Biodegradability , Starch , Polypropylene , Fungi Culture Medium