Effect of graphene nanoplatelets on the ballistic performance of hybrid Kevlar/ Cocos nucifera sheath-reinforced epoxy composites

This study investigated the effect of graphene nanoplatelets (GnPs) on the ballistic performance of Kevlar/ Cocos nucifera sheath-reinforced epoxy composites. GnPs with different wt. % (0%, 0.25%, 0.50%) were integrated into epoxy resin through ultra-sonication. Laminated composites were fabricated by incorporating Kevlar and Cocos nucifera sheath layers into the epoxy/GnP mixture by the hand lay-up method followed by hot pressing. Nine- and 12-layered laminates were fabricated with different numbers of Kevlar and Cocos nucifera sheath plies. Ballistic tests were conducted using a single-stage gas gun experimental setup with an 8 mm hemispherical stainless steel projectile. The results showed that the addition of GnPs improved the energy absorption by 8.5% (nine plies) and 12.88% (12 plies) and the ballistic limit by 4.28% (nine plies) and 6.17% (12 plies), respectively of Kevlar/epoxy/GnP composites at 0.25 wt. %. However, hybrid Kevlar/ Cocos nucifera sheath/epoxy/GnP composites and Cocos nucifera sheath/epoxy/GnP laminated composites decreased the energy absorption and ballistic limit after the addition of GnPs. This is because the addition of GnPs improved the interfacial interactions between the fiber and GnP modified epoxy matrix, which is inappropriate to absorb and dissipate the kinetic energy of the projectile. Statistical analysis was carried out using one-way analysis of variance and it was shown that there is a statistically significant difference between the obtained ballistic properties of the laminates.