Abstract
Positron annihilation lifetime spectroscopy (PALS) have been used to investigate the effect of filling each of poly (ethylene-co-vinyl acetate) (EVA), acrylonitrile butadiene rubber (NBR), and their blend (50/50wt-%) with different concentrations of high-abrasion furnace (HAF) (0–60 phr). PALS is characterised by the free-volume parameters (Vh and F %), which is a measure of the size and fraction of free-volume holes in the composites. The results show that the variation in Vh and F % of free-volume holes depends on the chemical structure and the degree of crystallinity of each polymer. The NBR has a smaller size (127.78 Å3) and lower fraction (4.18%) of free-volume holes than the corresponding free-volume holes (177.48 Å3 and 7.03%) in EVA. The size of the free-volume holes increases in EVA with increasing HAF content up to 20 phr in polymer matrix while it decreases in NBR. The fractions (F %) of free-volume holes decrease due to the reduction in positronium formation in polymer and positron trapping at polymer interface. The results also show an inverse correlation between free-volume parameters (Vh and F %) and tensile strength value, and a direct correlation with elongation at break as a function of HAF content in EVA and NBR. The electrical properties are negatively correlated with lifetime of free positron, τ2, and positively with its relative intensity (I2).
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