Thermal and mechanical properties of EPDM/PP + thermal shock-resistant ceramic composites

Dynamic vulcanizate blends of polypropylene (PP) and ethylene–propylene-diene rubber (EPDM) were filled with 5 wt% of micro-scale ceramic powder. To overcome the difficulty of particles dispersion and adhesion, the filler was modified through grafting using three kinds of organic molecules. A combination of Raman data with thermogravimetric analysis (TGA) results prove that grafting of organic macromolecules onto ceramic surfaces takes place. Dynamic mechanical analysis (DMA) has been performed from −100 to +50 °C; addition of the ceramic increases the storage modulus E′, more so for modified filler. Compared to PP and thermoplastic vulcanizate (TPV), a higher thermal expansion is seen after addition of the ceramic filler, a result of creation of more free volume. The tensile modulus of the composites is about 1.2 times that of pure TPV, an increase in the rigidity clearly caused by the ceramic. Fracture surfaces show weak bonding of filler particles to the matrix. In the sample containing modified filler the tensile deformation is going through the polymer matrix. The brittleness, B, decreases upon surface modification of the ceramic. The highest value of B is seen for the PP + unmodified ceramic while lower B values are obtained for TPV and its composites.