Tailoring Epoxy Composites with Acacia caesia Bark Fibers: Evaluating the Effects of Fiber Amount and Length on Material Characteristics

Abstract

In recent years, there has been growing interest in utilizing bark fibers as reinforcements for polymer composites. This study focused on the characterization of epoxy composites reinforced with Acacia caesia bark (ACB) fibers, considering their mechanical, morphological, and thermal properties. Various amounts of ACB fibers with three different lengths (10, 20, and 30 mm) were incorporated into the composites, ranging from 10 to 35 wt.% in 5% increments. This resulted in 18 sample categories, which were compared to neat epoxy samples. The findings demonstrated that the introduction of ACB fibers, even at the highest fiber content, led to improved mechanical performance. However, a transition in fiber length from 20 to 30 mm exhibited conflicting effects on the composite, likely due to the tendency of bark fibers to bend and split into fibrils during loading. Regarding thermal degradation, the advantages over neat epoxy were evident, particularly for 20 mm fibers, suggesting enhanced interfacial bonding between the matrix and the reinforcement. The epoxy adequately protected the bark fibers, enabling the composite to withstand degradation at temperatures comparable to pure resin, with minimal structural damage below 320 °C.