Reactive compatibilization of biodegradable blends of poly(lactic acid) and poly(ε-caprolactone)

Poly(epsilon-caprolactone) (PCL) was reactively blended with poly(lactic acid) (PLA) using three catalysts/coupling agents in a Haake twin screw mixing chamber. Triphenyl phosphite showed the most promising results as a coupling or branching agent. PLA and PCL were also melt blended without any catalyst/coupling agents in order to make a comparison of the properties. The transesterification reaction was monitored by measuring torque values as a function of time. H-1 NMR was used to characterize the structure of the reactive and physical blend products. The blend samples were characterized for physical properties and biodegradation. Mechanical property measurements indicated that the elongation of the PLA/PCL blends improved significantly when compared to pure PLA especially for the reactively compatabilized blends, and that a synergism was observed for certain compositions (PLA/PCL=80/20 or 20/80). Degradation studies showed that the enzymatic degradation rate (or normalized weight loss) of the reactively compatabilized blends were much higher than that of pure PLA and PCL, while the degradation rate of physical blends are between those of pure PLA and PCL. (C) 1998 Elsevier Science Limited. All rights reserved.