Although the size effects of a filler are closely related to the complex multi-level structures of their polymer composites; unfortunately

such relationships remain poorly understood. In this study

we investigated the effects of various sizes (40-600 nm) of silicon carbide (SiC) fillers on the wear behavior of ultrahigh molecular weight polyethylene (UHMWPE) in the presence of the silane coupling agent KH-560. All of these SiC fillers improved the wear resistance of UHMWPE significantly

with a medium size (150 nm) being optimal. To examine the reasons for this behavior

we analyzed the multi-level structures of the samples in terms of their matrix structures (crystalline; amorphous; interphase)

matrix-filler interactions (physical adsorption; chemical crosslinking; hybrid network) and the external effects of SiC fillers (bearing loads; transferring frictional heat). The high rigidity and thermal conductivity of SiC fillers and

more importantly

the intrinsic characteristics of the matrix structures (larger crystal grains; higher interphase; stronger amorphous entangled networks) were the key parameters affecting the enhancement in the wear-resistance of the UHMWPE. Herein

we also provide interpretations of the corresponding physical effects. Our results should improve our understanding of the structure-property relationships and

thus

should guide the formula design of UHMWPE composites.