Mechanical Properties and Electrical Conductivity of Carbon Black filled Polypropylene

Abstract

An attempt was made to improve the interfacial affinity between the carbon black (CB) and polypropylene (PP) by introducing the maleic anhydride-grafted-polypropylene (MAH-PP). x weight parts of MAH-PP were added to (100－x) weight parts of PP ; x＝O, 3, 5, 8, 10, 20. Then, 20 weight parts of CB particles were filled to make the composite specimen. Effects of MAH-PP content x on the flexural properties and electrical resistivity of the composite were investigated. Results obtained are as follows: (1) In the range of x≦8, the elastic modulus and strength of the composite have increased and the electrical resistivity has decreased with the increase of x. (2) When x＝20, the elastic modulus and strength have decreased and the resistivity has increased, inversely. (3) The composite with x=8 is annealed at various temperatures for 24 hrs. When the annealing temperatute is around the crystallization temperature (126℃), the annealed composite has exhibited the maximum elastic modulus and strength. Although the electrical resistivity increases, the PTC intensity (resistivity at peak temperature/resistivity at room temperature) has increased 4.5 times larger by the annealing compared to the quenched composite.