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

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 N-H and C-N 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 similar to 37%, the modulus and the strength of it increased by similar to 267 and similar to 151%, respectively. Equilibrium moisture regain of the treated fibers and their composites decreased by similar to 43% and similar to 40%, respectively. The tensile modulus of the composites increased by similar to 171%. Enhancement in tensile strength is observed but could not be quantified due to the difference in V-f and scatter in the data. SEM examination confirmed the enhancement in fiber-matrix bonding due to surface treatment.