Observations on the effectiveness of some surface treatments of mineral particles and inorganic compounds from Armenia as the fillers in polyphenylene sulfide for tribological performance

This is a general study in which a number of minerals and inorganic compounds from Armenia were investigated for their effectiveness as the fillers in polyphenylene sulfide (PPS) for tribological performance. The minerals studied were tuff, bentonite, and travertine, and inorganic compounds MoO3 and MoO2. The filled polymer specimens were prepared by compression molding and tested for tribological behavior in the pin-on-disk sliding configuration. The particulate fillers included many variations in terms of the size (micro and nano) and surface treatment. Friction and wear test results revealed that MoO2 and nano size bentonite particles were effective in improving the wear resistance. The lowest steady state wear rate in this study was observed for PPS+7% MoO2 (50 nm)+5% PTFE composite, and MoO2-filled composites had generally lower coefficients of friction than that of the unfilled PPS. From the wear plots, filler abrasiveness, and transfer film studies, it was concluded that the abrasion by filler was mostly responsible for the detrimental wear behavior. The wear behavior has been discussed in terms of the abrasion by filler and transfer film uniformity, texture, thickness, and coverage. The effects of particulate size and surface treatment are also included in the discussion. In view of the results reported for these fillers in formaldehyde and dioxolane copolymer (CFD) and the observations in this study, it is felt that the fillers from Armenia with the exception of tuff and MoO3 have considerable appeal for further investigation using other innovative surface treatments for fillers.