Flexural strength and ballistic performance of vinyl ester resin/aramid fiber composites toughened by graphene nanosheets

Abstract

The fiber reinforced polymer (FRP) armor composites are kinds of composite materials specially designed and manufactured to prevent the penetration of high-speed bullets and fragments. The FRP composites are commonly composed of reinforcing fibers, resin matrix and their interfacial structures. The vinyl ester resin (VER) is a kind of thermosetting resin commonly applied in the field of high performance bulletproof composites. However, the VER has the problem of insufficient toughness after curing, which seriously limits its application. In this research, the graphene nanosheets were homogeneously dispersed into VER matrix by ultrasonic-assisted dispersing process. The effects of graphene content on the mechanical and dynamic mechanical thermal properties of VER castings were investigated. The graphene-toughened VER/aramid fiber (AF) composites were prepared by hand layup-vacuum bag molding process. The influences of graphene content on the flexural strength and ballistic resistance of VER/AF composites were investigated. The results showed that the tensile strength, elongation at break, flexural strength and non-notch impact strength of VER casting filled with 0.1 wt.% graphene increased by 5.6%, 27.6%, 11.7% and 90.5%, respectively, compared with those of unfilled VER casting. The glass transition temperature Tg of VER casting gradually increased with the increase of graphene content. The hand layup-vacuum bag molding process effectively reduced the filtering effect of the fiber fabrics on graphene sheets. When the amount of graphene was 0.1 wt.%, the flexural strength of VER/AF composite was increased by 34.2%. Due to the improvement of fracture toughness of the resin matrix, the ballistic limit velocity V 50 and specific energy absorption of the VER/AF composites were both improved.