Comparative study on natural cellulosic and synthesized aramid fibers on mechanical properties of epoxy composite

Most of engineering applications require a series of properties which is not provided by a certain material. Therefore, composites production and utilization have extensively developed in various industries by materials combining. On the other hand, environmentally concerns compel environmentally friendly components in the composites manipulation. Then in this study, substitutability of imported synthesized Kevlar fiber by natural cellulosic fiber in epoxy resin matrix were investigated at presence and absence of nano bentonite. Dosages of 0.25 and 0.5 of fibers and 0.1 and 0.2 of nano bentonite were mixed into the epoxy resin and after bubble removal and complete curing, the composite panels were tested. The results showed that bubble removal and formation evenness mostly influenced the mechanical properties. So, tensile strength of 0.5% Kevlar composites was lower than its 0.25%. But opposite to the Kevlar, cellulose fiber increasing addition improved tensile strength and elasticity and rupture moduli properties, significantly. Consequently, 0.5% cellulosic fiber composite revealed higher the properties with lesser surface area demolished by the ballistic impact, which all attributed to shorter length of cellulosic fiber (1.8mm) compared to Kevlar (4.8mm), resulted in better composite formation. But Kevlar composite energy absorption (54 J) was higher than cellulosic composite (50 J). Individual incorporation of Kevlar and cellulose fiber into epoxy resin and their combinations with nano bentonite drastically reduced the demolished surface area (up to 10 cm2) and matrix cracks propagation with symmetrically pinned hole compared to the solely epoxy panels (10 cm2).