REACTION-INDUCED PHASE-SEPARATION IN POLY(BUTYLENE TEREPHTHALATE)-EPOXY SYSTEMS .1. CONVERSION-TEMPERATURE TRANSFORMATION DIAGRAMS

Poly(butylene terephthalate) (PET) was used as a semicrystalline modif ier of epoxy-aromatic diamine formulations. The epoxy monomer was base d on diglycidylether of bisphenol A (DGEBA) and the diamines were eith er 4,4'-methylenebis [3-chloro 2,6-diethylaniline] (MCDEA) or 4,4'-dia minodiphenylsulfone (DDS). PET was more miscible in DGEBA-MCDEA than i n DGEBA-DDS formulations, as revealed by the melting point depression observed in binary mixtures. Melting temperatures as a function of con version were obtained for both systems using differential scanning cal orimetry together with size exclusion chromatography. In the case of t he PBT-DGEBA-DDS system, a cloud-point curve was also obtained, showin g an upper-critical-solution-temperature behaviour. On the basis of me lting, cloud-point, vitrification and gelation curves, conversion-temp erature transformation diagrams were generated for both systems. These diagrams can be used to design particular cure cycles to generate dif ferent morphologies in the phase separation process. In the case of PB T-DGEBA-MCDEA systems, PET could be either kept in solution in the mat rix or separated by crystallization (initially or in the course of pol ymerization). For PBT-DGEBA-DDS systems, PET was always segregated fro m the matrix, either initially through crystallization or by attainmen t of the cloud-point curve in the course of reaction. Morphologies gen erated and resulting mechanical properties will be discussed in the se cond part of the series. Copyright (C) Elsevier Science Ltd.