Effect of fiber surface treatment on mechanical, interfacial, and moisture absorption properties of cattail fiber-reinforced composites

Abstract

Surface treatment of cattail, a lignocellulosic renewable fiber, was investigated to determine the conditions that would reduce moisture absorption while maximizing the properties of cattail fiber-reinforced unsaturated polyester composites. Surface modification of cattail fiber was studied by treating them with 2.5, 5, and 10% of 1,6-diisocyanatohexane (DIH) and 2-hydroxyethyl acrylate (HEA) for three different immersion times (10, 20, and 30 min). DIH-HEA treated fibers were preformed into a non-woven mat and impregnated with unsaturated polyester resin to manufacture composite. The existence of covalent bonds on the treated fibers via NH and CN groups was confirmed by FTIR spectroscopy. The 10% DIH-HEA resulted in the best results; while the mean diameter of the treated fiber decreased by ~37%, the modulus and the strength of it increased by ~267 and ~151%, respectively. Equilibrium moisture regain of the treated fibers and their composites decreased by ~43% and ~40%, respectively. The tensile modulus of the composites increased by ~171%. Enhancement in tensile strength is observed but could not be quantified due to the difference in Vf and scatter in the data. SEM examination confirmed the enhancement in fiber–matrix bonding due to surface treatment.