Micromechanical Characterization of Continuous Fiber Date Palm Composites

Date palm fiber composites with aligned, continuous fibers and epoxy matrix were prepared and mechanically characterized using micromechanical models. A hydrothermal process with microwave heating was utilized to extract the date palm frond (midrib) fibers, making the process eco-friendly as opposed to the commonly reported chemical extraction method. Single fibers were then characterized and found to have an average elastic modulus and ultimate tensile strength of 17.1 ± 1.5 GPa and 333 ± 27.4 MPa, respectively. Interfacial shear strengths ranging between 6 and 12 MPa were determined using a single-fiber pull-out test. Fibers were aligned to make uniaxial tensile samples with volume fraction ranging from 11% to 56%, elastic modulus ranging from 1.72 GPa to 9.52 GPa and ultimate tensile strengths ranging from 16.9 MPa to 43.8 MPa. All the results were found to obey "Rule of Mixtures" theory. The composite's mechanical properties are similar to or exceeding those of the commercially available wood products such as medium density fiberboard, oriented strand board, thick particle board, hard fiber board, and plywood, making the hydrothermal approach with microwave heating as a promising approach for preparation of date palm composites and further opens up similar process pathway for other natural fibers.