Tribological properties of polyoxymethylene composites (Part 1): relationship between spherulite size and specific wear rate

摘要

The spherulite size of polyoxymethylene (POM), which was a semicrystalline polymer, was changed by adding a small amount of inorganic particles of silicon carbide (SiC) and by the method of molding of polymer pin test specimens. The effect of a change of the spherulite size on tribological properties was evaluated by using a pin-on-disk type friction and wear-testing machine. Besides, mechanical properties of SiC-filled POM composites were evaluated as well. Then, using polymethyl methacrylate (PMMA) as so-called amorphous polymer in which spherulites were not formed tribological properties of SiC-ifiled PMMA composites were evaluated. Obtained results showed no effect of the filling up with SiC on friction and wear properties in the case of PMMA in which spherulites were not formed. However, in the case of POM in which spherulites were formed, a reduction of the spherulite size up to 30μm by changing temperature of the mold or by filling up with SiC up to 0.5 vol % did not show any effect on the coefficient of friction, but an effective reduction of the specific wear rate resulted. The minimal specific wear rate of 10{sup}(-6) mm / Nm was obtained when filling up with SiC in the amount of 0.5 vol %. when filling up with SiC in amounts below 0.5 vol % mechanical properties of POM composites did not show a significant change with a change of the amount of filled SiC.