Effect of the Talc Filler Content on the Mechanical Properties of Polypropylene Composites

This research examines the effect of a microsize/nanosize talc filler on the physicochemical and mechanical properties of filled polypropylene (108MF10 and 33MBTU from Saudi Basic Industries Corp. and HE125MO grade from Borealis) composite matrices. A range of mechanical properties were measured [tensile properties, bending properties, fracture toughness, notched impact strength (at the ambient temperature and -20 degrees C), strain at break, and impact strength] along with microhardness testing and thermal stability testing from 40 to 600 degrees C as measured by differential thermal analysis and thermogravimetric analysis. Increasing filler content lead to an increase in the mechanical strength of the composite material with a simultaneous decrease in the fracture toughness. The observed increase in tensile strength ranged from 15 to 25% (the maximum tensile strength at break was found to be 22 MPa). The increase in mechanical strength simultaneously led to a higher brittleness, which was reflected in a decrease in the mean impact strength from the initial 18 kJ/m(2) (for the virgin polypropylene sample) to 14 kJ/m(2), that is, a 23% decrease. A similar dependency was also obtained for the samples conditioned at -20 degrees C (a decrease of 12.5%). With increasing degree of filling of the talc-polypropylene composite matrix, the thermooxidative stability increased; the highest magnitude was obtained for the 20 wt % sample (decomposition temperature = 482 degrees C, cf. 392 degrees C for the virgin polymer). (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 110: 2742-2747, 2008