The purpose of this research is to determine the tensile stress and interfacial shear stress of coconut fiber that has been treated Sodium Hydroxide and Potassium Permanganate. This research is divided into three stages: soaking for 3 hours, testing, and data analysis. Coconut fiber is soaked in a solution of 5%, 10%, 15%, and 20% sodium hydroxide solution. Then, soaking in a solution of Potassium Permanganate with concentrations of 0.25%, 0.50%, 0.75%, and 1.00%. After that, the coconut fiber is dried in the furnace at 90 o C for 5 hours. Then, coconut fiber was tested for tensile stress and interfacial shear stress. Based on the results of the test can be concluded that the treatment of Sodium Hydroxide and Potassium Permanganate affect tensile strength, and the shear strength of coconut fiber. The largest tensile stress was obtained in the treatment of Sodium Hydroxide with a concentration of 20% ie 289.94 N/mm 2 , while the highest interfacial shear stress was obtained in the treatment also on Sodium Hydroxide with a concentration of 20% ie 3.09 N/mm 2 .

The purpose of this study was to determine the grade of roughness of coconut fiber surface as result of sodium hydroxide and potassium permanganate treatment. Research stages are soaking for 3 hours, testing, and data processing. Coconut fiber is soaked in 5%, 10%, 15%, 20% sodium hydroxide solution. Then soaked in 0.25%, 0.5%, 0.75% and 1% potassium permanganate solution. After that, the coconut fiber is dried in the oven at 90 °C for 5 hours. Thereafter, measurement of surface roughness. The measurement of surface roughness was did in two methods namely SEM, and surface roughness gauge. Based on the results of the tests, it was concluded that the higher concentrations of sodium hydroxide and potassium permanganate solutions gave higher grades of surface roughness compared with untreated fibers.

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.

The long-term goal of this research is to makecoconut fiber composite as one of the technical material, forbuilding material such as ceiling board or for automotivematerial such as bumper. While the specific target to be achievedin this research is to determine the influence of the concentrationof alkali solution on soaking coconut fiber to the content of lignin,cellulose, and hemicelluloses of coconut fiber. To achieve theobjectives and targets, the method of implementation of thisresearch is divided into 4 (four) steps, namely (1) preparation, (2)immersion, (3) testing, and (4) analysis. Coconut fiber is treatedby soaking coco fiber for 3 hours in sodium hydroxide (alkali)solution with concentrations of 5%, 10%, 15%, 20%, 25%, 30%,35%, 40%, 45%, 50%, and 55%. Once soaked, the coconut fiberis rinsed with aqua, then dried in an oven at 60°C for 4 hours.After that, a composition test with hydrolysis method todetermine the content of lignin, cellulose, and hemicelluloses.Each variable will be tested 3 (three) times. The data obtainedwill be analyzed statistically by applying descriptive method,where all data obtained will be presented in table, graphic, orimage form. Based on the tables, graphs, and images will beanalyzed and drawn conclusions. The results to be achieved inthis study is to determine the content of lignin, cellulose, andhemicelluloses coconut fiber due to alkali treatment for 3 hourswith a variable concentration of alkali solution. Based on theresults and discussion it can be concluded that soaking coconutfiber in alkaline solution degrades the content of hemicelluloses,cellulose and lignin.

—The goals of this study was to determine the effect of alkali concentration in the soaking coconut coir fiber (S2K) to changes in coconut fiber diameter. Stages of implementation of the study are (1) the measurement of the diameter of S2K before soaking, (2) immersion S2K in an alkali solution (NaOH) at a concentration of 5%, 10%, 15%, 20%, and 25% for 3 and 5 hours, ( 3) after being soaked, S2K removed and rinsed with distilled water, (4) was dried in a room temperature of 30±2°C for 5 days, (5) the measurement of the diameter of S2K after soaking with digital microscope. Based on the results of tests performed concluded that (1) immersion in an alkali solution resulted in a reduction of the diameter of S2K, (2) on soaking 5 hours at a concentration of 15% NaOH solution obtained reduction diameter S2K largest percentage of 56.08%. Keywords: natural fibers, the concentration of alkali, wettability.