Analysis of the effect of concentration of sodium hydroxide (NaOH) on alkalization process as composite reinforcement on tensile strength of single fiber rice straw

Abstract

Natural fiber composites are very environmentally friendly because they can be degraded naturally and also the price of natural fibers is cheaper than synthetic fibers. The importance of pre-treatment of the fiber because it can increase the mechanical strength of the fiber itself. One of the pretreatments for fiber is to perform an alkalization process, including soaking the fiber in a solution of Sodium Hydroxide (NaOH) and the concentration of NaOH affects the mechanical strength of the fiber. So this study aims to determine the effect of NaOH concentration on the alkalization process on the mechanical strength of rice straw fiber (RSF). The stages of this research were soaking RSF in NaOH solution with concentrations of 2%,3% and 4% for 60 minutes and without treatment, then washing with distilled water, drying at room temperature for 7-8 days, making a single fiber tensile test sample and testing and analysis of fiber morphology structure with Scanning Electron Microscope (SEM). The results showed that the effect of 4% NaOH treatment on rice straw showed a maximum tensile stress of 82.23 MPa, a strain value of 28.2% and an elastic modulus of 291 MPa. SEM results showed that at 4% concentration of alkali treatment, fiber surface roughness, tears and small holes on the RSF surface showed that impurities were removed including lignin, resulting in increased fiber absorption. This can facilitate the absorption of the matrix against the fiber in composite manufacturing applications.