Effect of Curing Temperature on the Mechanical Properties of Hemp Fiber Reinforced Polymer Composites

Abstract

The main objective of this study is to investigate the effect of curing temperature on the mechanical properties of hemp fiber reinforced polymer (HFRP) composites. In this study, hemp fiber was considered as a reinforcement and epoxy resin with hardener as a matrix. The mercerization process was used to remove contaminants from the fiber surface. The overall volumetric fraction used was 40% fiber and 60% matrix. One composite sample was cured at open temperature (27 ± 3 °C) for 15 days and others at elevated temperatures such as 80, 120 and 160 °C for various durations such as 1, 2, and 3 h (h). Different mechanical tests were performed under ASTM standards to examine the mechanical performance of HFRP composites. The tensile and compressive properties such as Young’s modulus, tensile and compressive strengths are higher in the specimens cured at 120 °C for 3-h. The flexural strength and stiffness are maximum in the composites cured at 80 °C for 3-h. The maximum interlaminar shear strength representing the composite's resistance to delamination is observed at 120 °C for 3-h curing condition. The Fourier transform infrared (FTIR) study identifies that the chemical treatment has reduced the impurities present on the fiber surface. Scanning electron microscopic (SEM) studies indicate better fiber/matrix adhesion in specimens cured at elevated temperatures than those cured at open temperature. Finally, this study emphasizes that curing at elevated temperature (120 °C for 3-h) improves the mechanical performance of the NFRP composites.