Amphiphilic biodegradable copolymer, poly(aspartic acid-co-lactide):: acceleration of degradation rate and improvement of thermal stability for poly(lactic acid), poly(butylene succinate) and poly(ε-caprolactone)

Poly(L-lactic acid) (PLA) was melt-blended with a small amount of poly(aspartic acid-co-lactide) (PAL) or poly(sodium aspartate-co-lactide) (PALNa) and processed into homogeneous press films. The mechanical properties and transparency of such blends are comparable to that of the non-blended PLA film. The degradation behavior of the blend film in phosphate buffered solution, in compost and in soil was investigated in terms of the polymers' mechanical properties, molecular weight, morphology and crystallinity. The results suggested that PAL and PALNa are effective additives for accelerating the hydrolysis of PLA. The non-enzymatic hydrolysis rates of poly(butylene succinate) (PBS) and polycaprolactone (PCL) were also enhanced by the presence of PAL in the blend. The melting test of PAL/PLA blend film revealed that PAL can improve the thermal stability of PLA as well. (C) 2003 Elsevier Science Ltd. All rights reserved.