AMIDE-MODIFIED POLY(BUTYLENE TEREPHTHALATE) - THERMAL-STABILITY

The thermal stability of a poly(ester amide) copolymer (PBTA) based on poly(butylene terephthalate) (PET) and nylon-4,T with the diamide of butanediamine and dimethyl terephthalate (N,N'-bis(p-carbomethoxybenzo yl)butanediamine) and homopolymer PET was studied. The development of inherent viscosity and endgroup concentration was determined during pr olonged condensation reactions at 255-275 degrees C. Analysis of the k inetics lead to degradation rate constants for PET and PBTA with 20 mo l% amide (PBTA20). The degradation rate of PBTA20 was comparable to th at of PET, thus beta-elimination of the ester groups is the main degra dation mechanism in PBTA. At high temperatures ester-amide interchange reactions also take place in PBTA. The change in the melting temperat ure of PBTA has been related to the decreasing uniformity of the amide segment length. The decomposition was further studied by thermogravim etry and mass spectrometry. Copyright (C) 1996 Elsevier Science Ltd.