The Effect of Volume Fraction and Alkalization Treatment on Characteristic of Straw-Epoxy Hydrophobic Composites with Coating Method

The rapid development of the timber industry has caused the total capacity of the Indonesian timber industry to exceed the ability of production forests to provide raw materials sustainably. One of the industries that require a supply of wood as its main raw material is the furniture industry. The raw materials for furniture that are commonly used are logs and planks. In recent years, there has been the development of new materials that use natural fibers as polymer reinforcement, which can be used to replace wood materials. The material is a natural fiber composite. Composite materials reinforced with natural fibers are widely used in aerospace, automotive, circuit boards and other applications. One of the natural fibers that can be used as a composite is straw fiber. This high proportion of cellulose in straw fiber can be used for several things, one of which is composite materials. The utilization of rice straw fiber and epoxy as raw materials for making composites is an alternative to overcoming the increasing demand for wood. The purpose of this study was to determine and analyze the effect of volume fraction and alkalization treatment on the physical and mechanical characteristics of straw fiber composites, also to determine and analyze the effect of adding a coating of PE/SiO2 on the hydrophobic characteristics of straw fiber composites. The physical and mechanical properties of the composites were evaluated based on the SNI 03-2059-2006 and SNI-01-4449-2006 standard. The volume fractions used are 40%, 50%, and 60%. The length of the fiber used is 5 mm. And the alkalization variables used were 5% and 10% NaOH with 4 and 8 hours of immersion. The compressive strength decreased by adding fiber volume fraction and increased by higher treatment alkalization. The coating method can produce composite with the contact angle value of more than 90o.