Evaluation of degradability of hydroxypropylated potato starch/polyethylene blend films

Potato starch was modified by hydroxypropylation, and films were prepared from blends of polyethylene (PE) with hydroxypropylated starch (HPS) with different degrees of substitution. Thermal degradability of the films was evaluated by heat treatment at 70 °C for 12 weeks. The carbonyl index of HPS/PE films increased whereas that of native starch (NS)/PE films did not change during heat treatment. Additionally, tensile strength and percent elongation of HPS/PE films decreased during heat treatment with increasing degree of starch hydroxypropylation. Biodegradability was determined after incubation of the films with Pseudomonas aeruginosa ATCC 13388 at 35 °C for 4 weeks. The HPS/PE film inoculated with P. aeruginosa demonstrated a further increase in the carbonyl index and a decrease of mechanical strength when compared to the corresponding uninoculated control. The surface of the HPS/PE film incubated with P. aeruginosa was destroyed after incubation, as revealed by SEM.