The role of filler deformability, filler-polymer bonding, and counterface material on the tribological behavior of polyphenylene sulfide (PPS)

Fillers affect the tribological behavior of polymers by decreasing wear in some cases while increasing it in others. This work examines the deformability of fillers and relates this behavior to the effectiveness of fillers in modifying the tribilogical behavior. The tribological behaviors of polyphenylene sulfide (PPS) filled with the inorganic fillers Ag2S, CuS, ZnF2, and SnS were investigated in a pin-on-disk test system, The counterfaces used were tool steel and KBI-10 (a tantalum alloy). Sliding was performed at I nits speed and 0.65 MPa nominal contact pressure. It was found that Ag2S and CuS deformed plastically both under static compression and in sliding contact while ZnF2 and SnS did not. The worn surfaces of the Ag2S and CuS filled composites were smooth with little cracking and led to lower wear rates while the composites of ZnF2 and SnS had wear surfaces with extremely rough topography and deep cracking which led to higher wear rates. The flexure strength of these four composite materials was also measured to get an idea of the bonding between filler particles and polymer matrix. The Ag2S and CuS composites had flexure strengths much higher than those of the ZnF2 and SnS. It was concluded that the ability of filler particles to plastically deform and the quality of bond between the filler and the matrix determined whether the filler would improve or degrade the tribological behavior of PPS in sliding wear. (C) 2001 Elsevier Science B.V. All rights reserved.