Search Results (3)

Reliable ballistic armor systems are crucial to ensure the safety of humans and vehicles. Typically, these systems are constructed from various materials like fiber-reinforced polymer composites, which are utilized for a favorable weight to ballistic protection ratio. In particular, there has been a quest for eco-friendly materials that offer both strong mechanical properties and sustainable advantages. The present work conducted a ballistic analysis of epoxy matrix composites using raffia (Raphia vinifera) fibers from the Amazon region as reinforcement. The experiments investigated the limit and residual velocities of composites with 10, 20, and 30 vol% of raffia. The experimental density of the composites was lower than that of the epoxy. Fractured surfaces were examined by scanning electron microscopy (SEM) to reveal the failure mechanism. The results showed that composites with 10 vol% raffia fiber fabric had the highest ballistic energy absorption (168.91 J) and limit velocity (201.43 m/s). The ones with 30 vol% displayed a higher level of physical integrity. The SEM micrographs demonstrated the failure mechanisms were associated with delamination and fiber breakage. There was a small variation in residual velocity between the composites reinforced with 10, 20, and 30 vol% of raffia, with 826.66, 829.75, and 820.44 m/s, respectively. Full article

Nowadays, industries place a strong emphasis on low-cost, biodegradable materials with long lifespans. As a result, businesses are concentrating on creating composite materials utilizing the world’s plentiful supply of natural fibers. In this study, acacia and raffia fibers are combined with epoxy resin and a hand layup method to create a biodegradable composite laminate. This article investigates the effect of fiber orientation on the mechanical and morphological evaluation of composite materials that have been manufactured. Three different kinds of composites were fabricated in this work: Composite 1, which contained acacia fiber; Composite 2, which was built of acacia and raffia fiber; and Composite 3, which was made of raffia fiber. While Composite 2 is a hybrid composite in this instance, Composites 1 and 3 are monofiber composites. In accordance with the ASTM standards, testing was performed to investigate the different mechanical behaviors, including tensile, flexural, double shear, delamination, hardness, and impact. The results demonstrate that Composite 1 has strong tensile strength, flexural strength, double shear, and hardness tests with a 45° fiber orientation. The 90° fiber orientation of Composite 1 performs well in the inter delamination test. The result demonstrates that composite 1 of type 0 absorbs greater energy. Additionally, Scanning electron microscopy was used to conduct morphological examinations in order to investigate the internal structural failure of the composites. It was found that the composite laminate has fiber cracks, pullouts, and voids, which were reduced with the right curing times and stress. Full article

In recent decades, the unique characteristics of natural fibers have promoted their use as reinforcement in polymeric composites. This is verified in several industrial sectors, from packaging to automotive and civil construction. Among the natural fibers, the raffia fiber extracted from the palm tree Raphia vinifera and introduced in the Amazon region a long time ago; started to be considered for the production of polymeric composites only in recent years. For the first time, the effect of raffia fiber length and its alkali treatment on the mechanical properties of a polymer composite was disclosed. Tensile tests were performed in composites with raffia fibers randomly dispersed into terephthalate-based unsaturated polyester resin. The results showed an increase in the Young’s moduli, confirmed by ANOVA, for the composite with both untreated and alkali-treated fibers in comparison to the plain polyester, which characterizes a stiffening effect. The composites with alkali treated fibers exhibited similar tensile strength values for all lengths; however, their strengths are lower than those for the untreated condition due to a weak raffia fiber/polyester matrix adhesion. Therefore, this work fills the current knowledge gap on raffia fiber incorporation in polyester matrix and valorizes this abundant Brazilian resource, providing additional information towards the use of raffia fiber in polymer composites. Full article