Influence of molecular structure of blend components on the performance of thermoplastic vulcanisates prepared by electron induced reactive processing

Polypropylene (PP)/ethylene propylene diene rubber (EPDM) thermoplastic vulcanisates (TPVs) were prepared by electron induced reactive processing without use of any chemical vulcanizing agent, co-agent or other type of additive. Thus, the composition of PP/EPDM blend is not changed by this novel process and relationships between raw material, process, morphology and properties of TPVs can be studied in a simple way. Consequently, the molecular mass of PP as well as the amount and nature of diene (ethylidene norbornene or vinyl norbornene) were varied. Based on detailed mechanical, dynamic mechanical, morphological, thermal and rheological investigations as well as equilibrium solvent swelling measurements and solegel analyses it was found that molecular mass, amount and nature of diene influence the cross-linking efficiency. In addition, the use of low molecular mass blend components leads to PP-EPDM phase graft-links as well as increased values of elongation and tensile strength at break. (C) 2016 Elsevier Ltd. All rights reserved.