Sisal fibers are among the natural lignocellulosic ones with great impact resistance for potential use in polymer composites. This work evaluates the ballistic efficiency of the distinct individual components of a multilayered armor. These include the front ceramic, the back metallic sheet and the intermediate layer as either the conventional aramid fabric or a novel sisal fiber reinforced epoxy composite. Sisal fibers incorporated in epoxy resin plates with volume fraction of 30% were ballistic tested using the 7.62 caliber ammunition. The fibers were embedded under pressure in the epoxy resin matrix and cured at room temperature for 24 hours. The tested specimens were examined by scanning electron microscopy.

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Multilayered armor systems (MAS) composed of relatively lighter materials with capacity to provide personal ballistic protection are being extensively investigated and used in armor vests. A typical MAS to stand high impact energy 7.62 mm bullet has a front ceramic followed by an aramid fabric laminate, such as Kevlar™. Since both the army and municipal police personnel might need to wear an armor vest, a large number of vests needs to be supplied. In the case of Kevlar™, one of the most expensive MAS material with an expiration time of 5 years, the possibility of its replacement by an equally ballistic efficient low cost material and more durable could be a relevant economical advantage. Natural fibers composites have recently been investigated as possible alternatives for Kevlar™. In particular, the fiber extracted from the coconut fruit, known as coir fiber, normally disposed as waste, could be a low cost material for this purpose. Therefore, the present work investigated the possibility of using coir fiber mantle, with different volume fraction, reinforcing epoxy composites as MAS second layer. It was found that 30 vol% of coir fiber composite displayed similar ballistic performance as compared to Kevlar™ with substantial economical advantage.

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