Thermoplastic elastomers based on compatibilized poly(ethylene terephthalate) blends: effect of rubber type and dynamic curing

Thermoplastic elastomers containing poly(ethylene terephthalate) (PET) in 50 wt%, compatibilizer (glycidyl methacrylate grafted rubber or glycidyl methacrylate containing copolymer) in 30 wt% and various rubbers (20 wt%) were produced by melt blending with and without dynamic curing (dicumyl peroxide initiated). The static tensile (stress–strain behaviour) and dynamic mechanical thermal properties (DMTA) of the systems along with their phase morphology (scanning electron microscopy of cryofractured and etched surfaces) were determined. It was found that the blend compatibility with PET is strongly improved when a high acrylonitrile-containing nitrile rubber (NBR) and an ethylene-glycidyl methacrylate copolymer (EGMA) or a GMA grafted ethylene/propylene rubber (EPR-g-GMA) are used as rubber and/or compatibilizer in the blend recipes. The effect of dynamic curing on the tensile and DMTA properties of the blends was negligible. Fractographic inspection of the fractured surface showed the development of a co-continuous phase structure which was in accordance with learnings from the DMTA spectra.