Potential reinforcing properties of silane-modified rapeseed straw fibers in friction composites: Fractal dimension and circularity characterise powder flowability

The powder flowability of natural reinforcing fibers significantly affects their reinforcement. Cellulose reinforced fibers (RSF) were extracted from rapeseed straw waste and treated with silane-ethanol solution modification. Fractal dimension and three major shape factors (circularity, elongation and compactness) were used to characterise the flowability of RSF. The silane-modified RSF was characterised by fractal features and fractal dimension was the main factor affecting its flowability. k-mean clustering and box-plot analyses indicated that circularity had the most significant effect on flowability among all shape factors. Multiple stepwise regression analysis further yielded a two-parameter equation characterising the quantitative relationship between flowability and the combination of fractal dimension and circularity. Moreover, the incorporation of RSF resulted in an important transformation in the wear mechanism of the friction composites towards single abrasive wear, with a 44.1% increase in wear resistance.