Tribological properties of polyoxymethylene composites (Part 2): effect of reducing spherulite size on the wear

摘要

In the preceding work, it was clarified that in the case of reduction of spherulite size in pin-type polymer test specimens prepared from polyoxymethylene (POM) by changing setting temperature of dies or by adding a small amount of silicon carbide particles, the specific wear rate reduced by more than 2 orders of magnitude without practically changing mechanical properties of the test specimens. In the present work, Izod impact tests and differential scanning calorimetry (DSC) analysis were performed and the relationship between respective measurement results and a reduction of the specific wear rate was verified. Obtained results showed that a higher Izod impact strength resulted in a larger rate of reduction of the specific wear rate. It was established that a decrease of the specific wear rate was caused by an increase of the binding power between spherulites, the thickening of lamellae in spherulites determined by the DSC analysis, and an increase of entanglement of noncrystal chains followed after a reduction of the spherulite size.