LAUSR

In the present research polypropylene/expanded graphite(PP/ExpG) and polypropylene/graphene nanoplatelets (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 nanofiller in the polymer matrix and itwas 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 increase of its β-crystal phase and the formation of voids in its cross-section. Graphene nanoplateletsseem to protect the PP matrix from the ageing as in FTIR spectra of PP/GNP nanocomposite-in bothone and five times extruded- the peak corresponding to carbonyl degradation products of PP was barely visible. The tensile properties of aged nanocomposites, one andfive times re-extruded, were similar to thecorresponding non-aged, 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 PP matrix.