Dynamically vulcanized thermoplastic elastomers based on 4-methyl-1-pentene polymers

This study explores the use of semi-crystalline polypropylene (PP) and poly(4-methyl-1-pentene) (PMP) as a thermoplastic phase for the production of TPVs containing ethylene propylene diene monomer rubber (EPDM) as the elastomer phase. The presence of isobutyl pendant group results in the plastic phase having nearly similar amorphous and crystalline density. The replacement of PP in TPV with PMP produces fine dispersion of rubber particles in the thermoplastic phase. The high melting point of PMP enables the production of high temperature TPVs with use temperature > 150 ?. The change of thermoplastic phase to PMP is therefore an effective strategy in producing softer TPVs with superior high temperature properties. The unique microstructure of PMP with poor chain packing results in exceptional breathability (CO2 permeability) that is nearly 2-3 times relative to TPV containing PP. Additionally PMP-based TPV exhibits exceptionally low thermal conductivity (0.153 W/m.K) due to the plastic phase. The excellent insulating properties make PMP-based TPV suitable as material for thermal insulation Finally, by a judicious selection of processing oil, it is possible to refine the microstructure and dispersion of rubber particles in the TPVs. The replacement of mineral oil with ester oil with solubility parameter closer to the polyolefins leads to superior mechanical, permeability, and thermal properties.