Effect of filler composition and crosslinker concentration on the tribological behavior of spent germ particle-based polymeric composites

Thermosetting composites have been prepared by the use of a biobased resin and spent germ filler, which is a byproduct from a wet ethanol production plant. Microscale tribological measurements were performed on samples with different concentrations of the filler as well as the crosslinker using a ball-on-flat reciprocating microtribometer. Microscale friction and wear behavior during dry sliding were evaluated using a spherical silicon nitride probe (radius 1.2 mm) and a conical diamond (radius 100 μm, cone angle 90°) probe to impose different contact conditions. Finally, a pin-on-disc tribometer was used to study the macroscale wear properties at high loads against an alumina pin. Scanning electron microscopy (SEM) images of wear tracks on the samples were obtained to elucidate deformation mechanisms. All samples showed evidence of abrasive wear in both micro- and macro-scales. It was found that an increase in the concentration of the filler resulted in higher friction coefficients against Si3N4, while an increase in the concentration of the crosslinker lowered the abrasive wear depth. These results provide some insight into the effectiveness of using biobased spent germ–tung oil polymer composites as potential tribomaterials.