Phase morphology and relaxation behaviour of SEBS/PP blends

Commercial thermoplastic elastomers based on styrene-ethylene/butylene-styr ene block copolymers are complex blends containing inorganic fillers, plast icizers, additives, and as a thermoplastic polymer mostly polypropylene. Mo del compounds of SEBS and PP are investigated. It is shown that mechanical properties, thermal application limits and relaxation behaviour are determi ned by the phase morphology of the blends. Two methods are presented which were developed especially for the characterisation of thermoplastic elastom ers. Intermittent stress strain measurements can be used to describe the st rain recovery behaviour of the material. The relaxation behaviour can be st udied by thermal scanning stress relaxation tests which also allow to draw conclusions concerning the phase morphology.