Polyblend CPP and Bionolle with PP-g-MAH as compatibilizer. II. Biodegradability

The biodegradability of Bionolle and a CPP/Bionolle blend in two biotic env ironments, that is, soil and a lipase-enzyme solution, were evaluated using the mechanical properties and weight-loss data. It was noted that upon soi l burial the tensile strength and elongation at break of polyblends were si gnificantly reduced, particularly after 3 months. The time of complete loss of strength as predicted from the curve-fit model was found sequentially t o be 6.80, 5.03, 4.84, 11.49, and 140.25 months for Bionolle, compatibilize d Bionolle, and CPP/Bionolle (25/75), (50/50), and (75/25), respectively. M eanwhile, the weight loss of polyblends during soil burial were observed to generally increase with increasing Bionolle content. Even a synergistic ef fect on the weight loss was shown by compatibilized Bionolle and CPP/Bionol le (25/75). Additionally, the time for complete weight loss as estimated fr om the curve-fit model was 12.57, 7.33, 7.01, and 13.90 months for Bionolle , compatibilized Bionolle, and CPP/Bionolle (25/75) and (50/50), respective ly. From the enzymatic degradation, it was recognized that in the early sta ge of biodegradation both the amorphous phase and the crystalline parts wer e randomly attacked. It was found that the weight loss that resulted from e nzymatic degradation was satisfactorily described by a generalized kinetic curve derived from a first-order reaction. (C) 1999 John Wiley & Sons, Inc.