▎ 摘　　要

In the present research polypropylene/expanded graphite (PP/ExpG) and polypropylene/graphene nanoplatelet (PP/GNP) composites were prepared by melt blending and their morphology and tensile properties were investigated. Although both reinforcements improved the elastic modulus of PP, PP/GNP composite presented better dispersion of the nanofiller in the polymer matrix and it was selected for further re-extrusion and ageing experiments. The re-extrusion affected the content of crystal phases of PP in pure PP and in its nanocomposite with GNP and increased their elastic modulus. The ageing of one and five times re-extruded PP caused an increase of the -crystal phase and the formation of voids in the cross-section. GNPs seem to protect the PP matrix from ageing as in Fourier transform IR spectra of PP/GNP nanocomposite, both one and five times extruded, the peak corresponding to carbonyl degradation products of PP was barely visible. The tensile properties of aged nanocomposites, one and five times re-extruded, were similar to those of the corresponding non-aged composites, whereas in aged PP the tensile strength and strain decreased significantly compared to non-aged PP. The anti-ageing effect of graphene can prolong the life of the PP matrix. (c) 2017 Society of Chemical Industry