Thermogravimetric study of copolymers derived from p-dioxanone, L-lactide and poly (ethylene glycol)

Thermogravimetric (TG) and differential thermogravimetry (DTG) analysis of the block copolymers based on poly (p-dioxanone) PPDO or Poly (L-lactide) PLLA or poly (p-dioxanone-co-L-lactide) PDO/PLLA and diol-terminated poly(ethylene glycol) PEG segments is reported. The effect of copolymer composition on the thermal stability of the copolymer under nitrogen and air is discussed. For comparison, the degradation behaviours of the starting oligomers and their corresponding homopolymers were also studied. The results showed that under nitrogen copolymers exhibited two degradation steps that can be ascribed to the PPDO or PLLA or PDO/LLA and PEG segments, respectively. However, under air copolymers exhibited, almost a single degradation step. Most of the copolymer samples showed higher stability in air than in nitrogen. All the copolymer samples in air as well as in nitrogen were eventually burnt almost completely. (C) 2002 Elsevier Science Ltd. All rights reserved.