| Linear low-density polyethylene films were prepared that contained native corn starch (7, 14, or 28%), low- or high-molecular weight oxidized- polyethylene (15%) and a pro-oxidant mixture (manganese 55 ppm and vegetable oil). Each plastic blend was first mixed in a twin-screw extruder at 195;Thermal and photodegradation properties of each film were evaluated by 70;Biodegradability was determined by using a pure-culture assay with ligninolytic Streptomyces badius 252, S. setonii 75Vi2, and S. viridosporus T7A and by using an extracellular-enzyme assay prepared from S. setonii 75Vi2 culture concentrate. The results from the pure-culture assay were inconclusive because of biomass accumulation on the film surface which inhibited chemical and biological degradation of the films. The extracellular-enzyme assay illustrated biodegradation for all 14 and 28% starch-polyethylene films, which suggests that the starch-polyethylene films could degrade in a biologically active compost environment.;The food packaging potential of each film was evaluated. The films were stable in paraffin oil and alkali but were not stable in strong acids. Starch in the films did not impair the heat sealing property. Water vapor transmission of the films increased with increasing starch content, whereas oxygen permeability was not affected by the addition of oxidized-polyethylene nor starch. Starch in the films did not accelerate microbial growth in wrapped ground beef and most films showed relatively inert mechanical properties after use. Consequently, degradable films containing 7 to 14% starch, oxidized-polyethylene and pro-oxidant illustrated good degradability and food packaging potential. |
