The Effect of Alkali Treatment and Addition of Microcrystalline Cellulose (MCC) on Physical and Tensile Properties of Ramie/Polyester Laminated Composites

The aim of this research is to investigate the effect of alkali treatment of ramie fibers and addition of MCC on the properties of ramie/polyester laminated composites. The alkali treatment was performed using NaOH solution at a room temperature. The laminated composites was manufactured using a vacuum infusion method for three layers of treated woven ramie fibers in the polyester matrix. The MCC (microcrystalline cellulose) powder 0.5 wt.% was added into the polyester resin and then mixed by a mechanical stirrer at a rotation speed of 350 rpm for 5 minutes. The physical characterization was evaluated using FTIR, XRD, and SEM methods. The tensile test of a single fiber and laminated composites was carried out according to the ASTM D3379 and ASTM D3039, respectively. The experimental results show that the XRD of treated fiber with 5 wt.% NaOH solution has the highest crystallinity index of 66.3%. It impacts the increase of tensile strength and elastic modulus of single ramie fiber by 18% and 55%, respectively. The addition of MCC into the polyester matrix of laminated composite can increase the tensile strength and elastic modulus by 18% and 21%, respectively, compared to the untreated laminated composite. In addition, the treated fibers laminated composite can improve the adhesion and chemical bonding between fibers and polyester as a matrix. The addition of MCC filler may prevent the initial propagation of cracks on interlaminar surfaces of laminated composite.