Influence of thermally induced self‐assembly shish‐kebab crystal on charge transport behaviour in polypropylene/elastomer blends

Abstract

This paper reports on the influence of thermally induced self‐assembly shish‐kebab crystal on charge transport behaviour in polypropylene (PP) and PP/propylene‐based elastomer (PBE) blends. The film samples with the shish‐kebab crystal were prepared by adding a β nucleating agent TMB‐5 under thermally induced self‐assembly. Polarised optical microscope （POM）, X‐ray diffraction (XRD) and differential scanning calorimetry (DSC) measurements were performed to understand the crystallisation characteristics of samples. Carrier trap distribution was analysed by isothermal surface potential decay (ISPD) method, and DC breakdown strength measured as well. The decrease of shish‐kebab crystal size, the reduction of trap level, the increase of shallow trap density and the decrease of deep trap density were obtained with the TMB‐5 content. The hopping distance of charges decreased with the shallow trap density increasing. The DC breakdown strength for PP/PBE/TMB‐5 was higher than that for PP/TMB‐5. It is suggested that deep traps are formed on the clear shish‐kebab crystal boundaries, while shallow traps are induced by the elastomer and the un‐crystallisation nucleating agents. Both the carrier trap formation on the crystal boundary and the physical channel orientation of the shish‐kebab crystals affect the charge transport behaviour.