The reinforcing effect of Kevlar? para-aramid pulp and floc short fiber on the natural rubber compound were investigated.The results showed that，as the addition level of fiber increased，the increase in storage modulus of Kevlar? para-aramid pulp reinforced rubber was greater than that in loss modulus；the loss angle and loss factor decreased as the addition level of pulp reduced.This effect was desired in tire component formulation and low rolling resistance tires design， since the tensile modulus increased without increasing hysteresis heat build-up.This unique behavior of low hysteresis heat build-up at increasing modulus may be attributed to the “accordion” effect Kevlar? para-aramid pulp.
