COMPOSTING OF MISCIBLE CELLULOSE-ACETATE PROPIONATE-ALIPHATIC POLYESTER BLENDS

A series of miscible blends consisting of cellulose acetate propionate (CAP) and poly(ethylene glutarate) (PEG) or poly(tetramethylene gluta rate) (PTG) were evaluated in a static bench-scale simulated municipal compost environment. Samples were removed from the compost at differe nt intervals, and the weight loss was determined before evaluation by gel permeation chromatography, scanning electron microscopy, and H-1 N MR. The type of polyester (PEG versus PTG) in the blend made no differ ence in composting rates. At fixed CAP degree of substitution (DS), wh en the content of polyester in the blend was increased, the rate of co mposting and the weight loss due to composting increased. When the CAP was highly substituted, little degradation was observed within 30 day s and almost all of the weight loss was ascribed to loss of polyester. Although the polyester was still observed to degrade faster, when the CAP DS was below approximately 2.0, both components are observed to d egrade. The data suggests that initial degradation of the polyester is by chemical hydrolysis and the rate of this hydrolysis is very depend ent upon the temperature profile of the compost and upon the DS of the CAP.