Abstract
Natural fiber-reinforced composites have attracted considerable attention due to their environmentally friendly, biodegradable, and recyclable characteristics. Hemp fiber, in particular, has been utilized across various industries owing to its superior mechanical properties. Similar to other natural fibers, hemp fibers require certain chemical modifications to enhance interfacial bonding with polymer matrices and to reduce their hydrophilic nature. In this study, acetyl and capryloyl cellulose esters were synthesized under microwave reaction conditions to improve the weak fiber/matrix interface in hemp fiber-reinforced composites. In acetyl chloride modifications, tensile strength increased by up to 38.5% and flexural strength by up to 44.3% compared to the untreated sample. Among the capryloyl chloride modified samples, the highest tensile strength was observed in hemp composites modified with 15% capryloyl chloride with an increase of 39% while its flexural strength improved by 53.4% over the untreated sample. Yarn pull-out tests indicated that interfacial shear strength (IFSS) at hemp fiber/epoxy interface increased after chemical modifications showing an improved fiber/matrix bonding. Contact angle measurements confirmed that the modifications rendered the fiber surface more hydrophobic. SEM analyses supported these findings, showing noticeable improvements at the fiber–matrix interface with treatments.
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