BIODEGRADABLE POLYESTER FILMS

Eight polyester films derived from C, to C, 0 a, coaliphatic diols and C, to ClO dicarboxylic acids were examined to determine differences in biodegradability. Two test procedures were used to evaluate degradation: agar plate cultures with a mixture of Aspergilli, and soil burial. After one month exposure of different polyester films to the agar culture test, there were large variations in microbial growth. In soil burial tests, weight loss of polymer from 3 to 40 per cent was obtained after burial for one month. The order of polyester degradability in the agar culture test differed from that found in the soil burial test. The relative degradability of the polymers examined seems to be related to the carbon chain spacing between ester groups. Mere physical hlending of degradable vegetable oil with stable vinyl plastics is insufficient to impart degradability to the polymer.