▎ 摘　　要

The quantitative characterization of microstructure is most desirable for the establishment of structure-property relationships in polymer nanocomposites. In this work, the effects of graphene on the microstructure, mechanical, electrical, and thermal properties of the obtained graphene/polyethylene (PE) composites were investigated. In order to reveal the structure-performance relationship of graphene/PE composites, especially for the effects of the relative free volume fraction (f(r)) and interfacial interaction intensity (beta), positron annihilation lifetime spectroscopy (PALS) was employed for its quantitative description. The relative free volume fraction f(r) gives a good explanation of the variation for surface resistivity, melting temperature, and thermal stability, and the variation of tensile strength and thermal conductivity agree well with the results of interfacial interaction intensity beta. The results showed that f(r) and beta have a significant effect on the properties of the obtained graphene/PE composites, and the effect on the properties was revealed.