Effect of shape morphology on mechanical, rheological and tribological properties of polyoxymethylene/aramid composites

This paper highlighted the morphological effect of aramid, i.e. fibers and particles, on friction and wear properties of polyoxymethylene (POM)/aramid composites under dry frictional conditions. Meanwhile, the mechanical, rheological and crystalline properties were also studied as a function of filler content. Results showed that addition of aramid short fibers (ASF) and particles (AP) affected the frictional behavior of POM in two different ways due to distinguished packing structure in composites. The mechanical performance of aramid short fibers filled POM composite outweighed that of POM/AP composite because of quite well length retention of aramid fibers, however this kind of morphology appeared not helpful to the enhancement of wear resistance. Dynamic rheology analysis confirmed the existence of network structure of POM filled with aramid short fiber, which was consistent with SEM observation of the worn scar surfaces. Compared with aramid particles, the entanglement and overlap of aramid fibers made it hard to deform under the same frictional conditions and could not to protect the matrix effectively, thus led to poor wear resistance.