Thermoplastic Vulcanizates by Reaction-Induced Phase Separation of a Miscible Poly(ε-Caprolactone)/Epoxy System

Abstract

Abstract A new method for the preparation of thermoplastic vulcanizates (TPVs) was successfully applied. Starting with a miscible system of a semi-crystalline thermoplastic polymer and an elastomer precursor, phase separation was induced by the increase in molecular weight during selective crosslinking of the elastomer precursor. As a model system, the semi-crystalline thermoplastic poly(Ε-caprolactone) (PCL) was used in combination with a rubbery epoxy resin based on poly(propylene oxide) (PPOn-epoxy). This approach enables the dispersion of up to 80 wt% of crosslinked rubber in a thermoplastic matrix, providing morphologies that are typical for TPVs. A range in rubber particle size of 0.5 to 3 μm was obtained by this new method, without the need of blend compatibilization or dynamic processing. The materials exhibit mechanical and rheological properties typical for TPVs and the rubber particles feature a high crosslink density. At high curing temperatures and high PPOn-epoxy contents, connectivity of the rubber particles is observed, which is attributed to the phase separation mechanism. Connectivity of the rubber particles has a negative influence on both the mechanical properties and the rheological behavior.