EFFECT OF PROCESSING ADDITIVES ON (BIO)DEGRADABILITY OF FILM-BLOWN POLY(EPSILON-CAPROLACTONE)

Poly(epsilon-caprolactone)s (PCL) with slip masterbatch, Erucamide, Si O2 and Erucamide + CaCO3 as low-molecular-weight processing additives, were film-blown in a single screw extruder. The films and recycled PC L without additives were exposed to composting, anaerobic sewage sludg e (37 and 55 degrees C), pure fungal culture, and chemical hydrolysis at two pH (7 and 10.5) and at two temperatures (room temperature and 5 0 degrees C). Recycling and addition of processing additives resulted in a slightly slower degradation rate compared with the degradation of pure PCL. The degradations in biotic environment were generally faste r than in abiotic environment. Higher degradation rates are observed i n more complex environments (composts and anerobic sewage sludge) due to synergism between high temperature and a richer fauna of microorgan isms. In the biotic environments, faster reductions in number-average molecular weight ((M) over bar(n)) than in weight-average molecular we ight ((M) over bar(w)) were observed. A decrease of (M) over bar(n) wi th up to 75-80% was estimated for composted pure PCL, while similar sa mples in anaerobic sludge at 55 degrees C were completely degraded in 50 days. The mechanical properties of the samples subjected to compost ing exhibited a more rapid enbrittlement compared to the samples subje cted to abiotic hydrolysis. The observed increase in crystallinity wit h increasing degree of degradation is explained by crystallization mad e possible by chain cleavage in the amorphous phase. (C) 1998 John Wil ey & Sons, Inc.