Dynamic mechanical properties of multi-functional epoxy resin filled with aramid short fibers

Three heat resistant multi-functional epoxy resin were filled with Aramid (Technora®) short fibers (AFP) by 2.4 wt% using four kinds of hardeners. AFPs observed by SEM on the fracture surface were dispersed randomly. Dynamic mechanical properties and flexural strength of those composites were measured. Although the glass transition temperatures Tg of the multi-functional epoxy resin matrix varied when combined with different hardeners, they were all high (over 200° C) and the highest temperature reached 260° C. The storage modulus E' of the material increased when AFP was added and remained at over 2 GPa even at 150° C. The value of E' in the glassy region was higher than the estimated value by the rule of mixtures which shows that the effect of AFP filling was remarkable. The relative modulus at Tg and the ratio of the peak height of tan δ implied that the affinity of epoxy resin with AFPs was large. The flexural strength of the matrix (epoxy resin) for less tough materials was larger than that for tougher but brittle materials. Although filling with AFPs reduces the flexural strength of the material, this significantly depends on the type of the matrix material.