Natural fiber reinforced polymer composites have recently been investigated as a component of multilayered armor system (MAS). These composites were found to present advantages when replacing conventional high strength synthetic aramid fabric laminate composite (KevlarTM, with same thickness, as MAS second layer. Continuous and loose natural fibers were up to now mostly used to reinforce these ballistic composites. Only two natural fabrics reinforced polymer composite were so far used with same purpose. Therefore, this work investigated the possibility of substituting KevlarTM for three other natural fabrics, based on mallow and jute fibers, as reinforcement of epoxy composites. Fabrics made of either pure mallow, or 70%mallow/30% jute or 50%mallow/50% jute fibers were separately mixed with epoxy to produce laminate composite plates. These plates were set as second layer of Al2O3/Nb2O5 front ceramic MAS, that were ballistic tested against relatively high energy 7.62 mm ammunition. Indentation depth values caused by the bullet penetration in clay witness, simulating human body behind the MAS, were always found to be below the safety standard limit. These indentation values were similar to those obtained in MAS with KevlarTM as second layer. However, significant economical advantages favor the investigated natural fabric composites over the synthetic Kevlar.

Polymer composites reinforced with natural fibers have been increasingly investigated and applied as engineering materials owing to their economical, technical, societal and environmental advantages. The malva fiber, particularly an important resource in the Amazon region in Brazil, only recently begin to be investigated as possible composite reinforcement for engineering application. However, the mechanical properties of composites reinforced with malva fiber are still unknown. In this paper, the flexural behavior of epoxy matrix composites reinforced with continuous malva fiber was for the first time investigated. Specimens of continuous malva fibers aligned along an epoxy matrix were press-molded. Three-points bending test were performed and the fractured specimens were analyzed by SEM. The results showed a marked improvement in the composites flexural properties with the increase in the amount of reinforced malva fiber. This improvement was found to match the Rule of Mixtures, which revealed the unique potential of malva composites for engineering applications.