Poly(phenylene sulfide) magnetic composites. I. Relations of percolation between rheology, electrical, and magnetic properties

Poly(phenylene sulfide)/ferrosoferric oxide composites (PPS/Fe3O4) with various loading levels were prepared by melt compounding. The microstructure of composites was investigated using SEM and XRD. The rheological, electrical and magnetic properties were characterized respectively by the parallel plate rheometer, high resistance meter, and magnetometer. The results reveal that the Fe3O4 particles are well dispersed in the PPS matrix due to their nice affinity, which results in a weak strain overshoot at large amplitude oscillatory level. Both the rheological and the electrical responses of the composites show a typical percolation behavior. But the rheological percolation presents lower threshold (< 40 wt %) than that of electrical percolation (similar to 50 wt %), which is attributed to the difference structure of the percolation network. The magnetic response, however, shows good linear relation with Fe3O4 loadings, indicating that the physical percolation has little influence on the magnetic properties. This is mainly due to the yielded long-range magnetic interactions among Fe3O4 particles in the applied field, which are far stronger than those nonmagnetic physical interactions accounting for percolation. (C)2007 Wiley Periodicals, Inc.