Mechanical Properties of Multi-walled Carbon Nanotube Dispersion-controlled Olefin-based Dynamically Crosslinked Thermoplastic Elastomers

Abstract

Dynamically crosslinked thermoplastic elastomer (D-TPE) based on polypropylene (PP)/ethylene-propylene-diene copolymer rubber (EPDM) blends dispersed with surface-coated multiwalled carbon nanotubes (MWCNTs) were prepared as highly-reinforcing nanofillers. Two types of surface-coated MWCNTs, that is, a liquid paraffin (Par) -coated one for affinity with the EPDM phase, and an alpha-olefin (Ole) -coated one for affinity with the PP phase, were used for controlling the dispersion of MWCNTs in the D-TPE. In evaluating the degree of impact of the type and content of the surface-coated MWCNT on the true stress-stretch ratio curve in tensile testing of the MWCNT-dispersed D-TPE, the best fracture characteristic value (tensile true stress and tensile fracture stretch ratio) were obtained when Par-coated MWCNT of 1 vol% was added for the purpose of reinforcing crosslinked EPDM phase., Thus, in Par-coated MWCNT we have elucidated that the enhanced tensile properties of the MWCNT dispersed olefin-based D-TPEs are closely associated with the morphology of the Par-coated MWCNT dispersed D-TPE selectively localized in the crosslinked EPDM phase, showing that the state of MWCNT dispersion is closely linked to improvement of the fracture characteristic value in the true stress-stretch ratio curve.