Morphology and deformation behaviour of toughened blends of poly(butylene terephthalate), polycarbonate and poly(phenylene ether)

The morphology and properties of blends of poly(butylene terephthalate) (PBT), bisphenol A polycarbonate (PC), poly(2,6-dimethyl-1,4-phenylene ether) (PPE), toughened with styrene-ethylene/butylene-styrene (SEBS) rubber have been found to be strongly affected by spontaneous phase segregation which occurs during melt compounding. In the composition range of interest, such segregation leads to the formation of a unique microstructure in which dispersed particles of rubber-modified PPE are encapsulated by thin envelopes of PC and embedded in a PBT matrix. Electron microscopy and tensile dilatometry studies of partially and fully formulated PBT/PC/PPE/SEBS blends have been used to relate the morphology of these materials to their deformation behaviour.