Reaction-induced phase separation in poly(butylene terephthalate)-epoxy systems: 1. Conversion-temperature transformation diagrams

P. A. OYANGUREN; P. M. FRONTINI ; R. J. J. WILLIAMS; E. GIRARD-REYDET ; J. P. PASCAULT

POLYMER

ELSEVIER SCI LTD

Lugar: Amsterdam ; Año: 1996 p. 3079 - 3085

0032-3861

Poly(butylene terephthalate) (PBT) was used as a semicrystalline modifier of epoxy-aromatic diamineformulations. The epoxy monomer was based on diglycidylether of bisphenol A (DGEBA) and thediamines were either 4,4'-methylenebis [3-chloro 2,6-diethylaniline] (MCDEA) or 4,4'-diaminodiphenylsulfone(DDS). PBT was more miscible in DGEBA-MCDEA than in DGEBA-DDS formulations, asrevealed by the melting point depression observed in binary mixtures. Melting temperatures as a functionof conversion were obtained for both systems using differential scanning calorimetry together with sizeexclusion chromatography. In the case of the PBT-DGEBA-DDS system, a cloud-point curve was alsoobtained, showing an upper-critical-solution-temperature behaviour. On the basis of melting, cloud-point,vitrification and gelation curves, conversion-temperature transformation diagrams were generated for bothsystems. These diagrams can be used to design particular cure cycles to generate different morphologiesin the phase separation process. In the case ofPBT DGEBA-MCDEA systems, PBT could be either keptin solution in the matrix or separated by crystallization (initially or in the course of polymerization). ForPBT-DGEBA-DDS systems, PBT was always segregated from the matrix, either initially throughcrystallization or by attainment of the cloud-point curve in the course of reaction. Morphologies generatedand resulting mechanical properties will be discussed in the second part of the series