Effect of sodium hydroxide concentration on the tensile strength of coconut fiber

Abstract

The purpose of this research is to determine the effect of the concentration of sodium hydroxide on the tensile strength of coconut fiber. The materials used are coconut fiber, sodium hydroxide solution, distilled water, tensile testing machine, carton, glue. Coconut fibers are soaked for 3 hours in sodium hydroxide solution with concentrations of 25%, 30%, 35%, 40%, 45%, 50%, and 55%. After that, coconut coir fibers are rinsed with distilled water, then shredded in the oven at a temperature of 90°C for 5 hours. After that, coconut fibers were divided into 3 groups. The first group, coconut fiber is used for hydrolysis test which aims to determine the amount of lignin, cellulose, and hemicellulose contained in coconut fiber. The second group, coconut fiber is given a tensile test with standard ASTM 3379-02 to determine the tensile strength of coconut fiber. The third group, coconut fiber is used to observe the surface of coconut fiber with using SEM equipment. Based on the results of hydrolysis and tensile test It was concluded that (a) the concentration of sodium hydroxide had an effect on the amount of lignin, cellulose, and hemicellulose contained in coconut fiber, the tensile strength of coconut fiber, and the roughness of coconut fiber surface, (b) the coconut fiber surface is increasingly rough which allows an increase in bonding strength between coconut fiber and resin, (c) the highest tensile strength was obtained at 30% sodium hydroxide soaking 226,1 N/mm2.