ANTIPLASTICIZATION AND ABRASION RESISTANCE OF POLYCARBONATES IN THE CHARGE-TRANSPORT LAYER OF AN ORGANIC PHOTOCONDUCTOR

A correlation has been found between the abrasion resistance of polycarbonate layers of an organic photoconductor and the dynamic mechanical loss modulus of the glassy phase. In particular, the effect of diphenylhydrazone charge-transport molecules on the properties of various polycarbonate binder resins was studied by tensile testing and dynamic mechanical analysis. Dilution of polycarbonate by diphenylhydrazones lowers the T(g) and simultaneously increases the tensile strength and modulus, with a transition from ductile to brittle failure. This antiplasticization is accompanied by a suppression of the intensity and distribution of sub-T(g) mechanical relaxations in the polycarbonate matrix. The degree of antiplasticization correlates with molecular mobility and free volume in the amorphous state. The abrasion rate of the charge-transport layer of an organic photoconductor, formulated from the above components, was measured by the Taber test. Resistance to abrasion involving cyclic fatigue depends on the structure and composition of the polycarbonate-diluent system and correlates with the strength and position of the sub-T(g) dynamic mechanical relaxation.