Meticulous Analysis and Consequences of Microstructure Changes on Melt Rheology and Dynamic Viscoelasticity of Thermoplastic Vulcanizates upon Reprocessing

Thermoplastic vulcanizates (TPVs), which are a special class of elastomer alloy, prepared by dynamic vulcanization possess unique morphology of finely dispersed micron-size cross-linked elastomeric particles in a continuous thermoplastic matrix. The present study investigates the microstructure formation of elastomeric phase and its associated morphological changes during reprocessing of TPVs based on poly[styrene-b-(ethylene-co-butylene)-b-styrene] triblock co-polymer (S-EB-S) and solution polymerized styrene butadiene elastomer (S-SBR) by scanning electron microscopy and atomic force microscopy. Semi-efficient and efficient sulfur-based curing systems have been adopted to cure the elastomeric phase and a comparative study has been made to demonstrate and explain the effect of reprocessing on the melt rheology and dynamic viscoelasticity of the TPVs. The present work also provides a better insight and guidance to control the microstructure of the cross-linked elastomeric phase to prepare selectively co-continuous or dispersed phase morphology. (C) 2014 Wiley Periodicals, Inc.