MISCIBILITY AND BIODEGRADABILITY OF BLENDS OF POLY(LACTIC ACID) AND POLY(VINYL ACETATE)

Poly(lactic acid) (PLA) was melt blended with poly(vinyl acetate) (PVA ) using a single-screw extruder. The extruded films obtained were char acterized for miscibility, physical properties, degradation and surfac e morphology. Differential scanning calorimetry showed that all the as -extruded films were amorphous, and that the blends were compatible as only one glass transition temperature was observed. Results obtained from physical property testing indicated that the blends exhibit syner gism in the range of 5 to 30% PVA, probably due to some interactions t aking place in that region. Enzymatic degradation studies showed that there was a vast difference in the weight loss of pure PLA samples and the 95/5 PLA/PVA blend. Surface tension results showed that this was due to the vast difference in the surface tension of the pure PLA film s and the 95/5 blend. Deaged-free blends showed the maximum degradatio n, followed by aged-extruded and then deaged-fixed. Scanning electron micrographs showed that the mode of degradation differs for the aged a nd deaged samples. A uniform degradation pattern was seen in the case of deaged samples while the aged samples showed a non-uniform pattern of degradation.