Dynamic mechanical behavior of LLDPE composites reinforced with Kevlar fibers/short glass fibers

Kevlar fibers (DuPont) and glass fibers have been used to reinforce linear low-density polyethylene (LLDPE) by using an elastic melt extruder and the compression molding technique. The impact behavior of hybrid composites of different compositions is compared and has been explained on the basis of volume fraction of fibers. The addition of glass fibers decreases the Izod impact strength of LLDPE. The Izod impact strength of the composite increases when glass fibers are replaced by Kevlar fibers. Dynamic mechanical alpha-relaxation is studied and the effect of variation of fiber composition on the relaxation is reported in the temperature range from -50degreesC to 150degreesC at 1 Hz frequency. The alpha-relaxation shifts towards the higher temperature side on addition of fibers in LLDPE. The addition of fibers increases the storage modulus, E', of LLDPE. The hybridization of Kevlar and glass fibers helps in designing composites with a desirable combination of impact strength and modulus. At the low temperature region, E' increases significantly with glass fibers as compared to that noted with the addition of Kevlar fibers. The alpha-transition temperature of composites increases significantly with Kevlar fibers as compared to that observed with addition of glass fibers.