Effect of water absorption on the mechanical properties of long date palm leaf fiber reinforced epoxy composites

Abstract

This paper examines the effect of the first 24 hours water absorption on the mechanical properties and morphology of the long date palm leave fiber (DPLF) and unidirectional reinforced epoxy composites. The mechanical properties that were evaluated are tensile and flexural. Laminates with 31.4% volume fraction of reinforcement was prepared using hand layout manufacturing technique. Scanning electron microscopy (SEM) was used to study the fiber morphology and fracture surfaces. The results revealed that the DPLF showed high hydrophilic behavior and reached saturation (98.4%) within 24 hours. The ultimate strength for DPLF decreased 60.7%. The coefficients of diffusivity (D) and moisture expansion (β) for unidirectional composites were estimated. The tensile/flexural results showed that water absorption decreased the specific ultimate strength and specific modulus by 14.8/14.5% and 40.1/17.8% respectively. However, it increased the specific toughness by 22.5/22.7%. The DPLF/epoxy composites showed less tendency for water absorption reaching only 3.5%. SEM examination of the dry composite after tensile showed fiber breakage, fiber pull out and fiber-matrix debonding whereas the composites after 24 hours showed fiber swelling, fiber pull out, debonding increase and matrix crack.