Thermo-Oxidation and Biodegradation Study of Low-Density Polyethylene /Starch Films by IR Spectroscopy

This article reports a study of the thermo-oxidation and biodegradation in the soil of low-density polyethylene/starch films (LDPE/starch) by infrared spectroscopy: Films of LDPE/Starch blends of different composition (starch content range from 0 to 15% w/w), were prepared and exposed to thermo-oxidation at different temperatures at 80, 90 and 100°C, and buried in the soil of public dump during 300 days. The oxidation, for films subjected to thermal oxidation, was revealed by the appearance of absorption bands of carbonyl groups centered at 1715 cm-1. After the induction period, which varies from 12 to 14 days according to the concentration of starch incorporated in the films, the indication of carbonyl croup increases with time and temperature of exposition. During the first 30 days, the rate of oxidization is the weaker, the larger percentage of starch in the film of LDPE. The biodegradation of films buried in the soil for 300 days, was followed by infrared spectroscopy. The carbonyl index calculated at 1715 cm-1 and at 1744 cm-1 showed the oxidation of films LDPE/starch. This index increases with time of burial and starch percentage incorporated into LDPE films during the first 180 days in soil burial, then decreases.