ANALYSIS OF THE MECHANICAL AND DEGRADATION PERFORMANCES OF SELECTED STARCH/POLYPROPYLENE BLENDS

Effects of starch content and compatibilizing agent on the tensile, water absorption and biodegradability properties of starch blended polypropylene (PP) have been investigated. The starches used in this study were native cassava and sweet potato starch. Dried cassava or sweet potato starch with particle size of 0.075 mm was used at 0-50 wt. % of PP, while polypropylene graft maleic anhydride was used as a compatibilizer at 10 wt. % based on starch content. The various starch/PP blends were prepared in an injection molding machine and injected as sheets. Tensile tests were carried out using Instron tester. The water absorption test and biodegradability of the blend samples by soil burial test were investigated for a period of 90 days. Results showed that the tensile properties of the compatibilized starch/PP blends were greater than the uncompatibilized starch/PP blends particularly at higher starch content. The water absorption of the various starch/PP blends increased with increase in starch content and immersion time, and decreased on addition of PP-g-MA to the blends. The percent weight loss due to degradation of the blends was observed to increase with increase in starch content and burial period, and decreased with the incorporation of PP-g-MA into the blends. The effects biodegradation of the various starch blended PP buried in the soil on the growth of wheat and soy bean plants studied indicated that plants grow normally in the soil containing the degraded blends. The interfacial properties between starch filler and PP matrix were improved after the addition of PP-g-MA as it is evident from the fracture micrographs using SEM.