Characteristics of water chestnut (Eleocharis dulcis) long fiber reinforced composite modified by NaOH and hot water

Abstract

The length and diameter of the reinforcing fibers in a composite greatly influence its tensile strength. This research investigated the physical and mechanical properties of composites reinforced with water chestnut (Eleocharis dulcis) long fibers. The fibers were modified with 5% NaOH and hot water (100 °C), each for one hour. Polyester was used as a matrix. The test refers to ASTM (American Society for Testing Materials) standards D638 and D790. The composite was made using the hand lay-up and vacuum bagging method. The volume fractions of water chestnut long fiber, e-glass, and polyester samples were 40%:0%:60%, 20%:20%:60%, 0%:40%:60%, 10%:30%:60%, and 30%:10%:60% (A, B, C, D, and E, respectively). The average density of water chestnut–reinforced composite modified by 100 °C hot water immersion and 5% NaOH treatment was 1.61–2.20 and 1.24–2.57 g/cm3, respectively. The tensile test results show that sample D had the highest average tensile strength at 134.68 and 130.13 MPa following immersion in hot water and 5% NaOH, respectively. The highest average modulus of elasticity (MoE) and modulus of rupture (MoR) for the modified composites were in sample C, at 7,580 and 235.53 MPa.