The effect of water absorption on the flexural strength and tensile strength of composites reinforced by fiber and woven of ramie (Boehmeria Nivea)

Abstract

Water absorption in a composite can be interpreted as the ability of a composite to absorb water within a certain time. Water absorption is characterized by changes in weight, volume, and density of the composite. This study aims to analyze the effect of water absorption on the flexural strength and tensile strength of ramie fiber and ramie woven composites. The research methodology used to calculate the amount of water absorption, flexural strength, and tensile strength is based on ASTM D570, D790-02, and ASTM D638-02 standards. The panels are immersed in seawater on a laboratory scale with a variation of the salinity levels of 30 ppm, 40 ppm and 50 ppm. The removal of the panels was carried out every variation of the immersion time, namely 0, 2, 4, 6, and 8 weeks. The results obtained show that the immersion time and salinity levels can affect the percentage of water absorption of the composites reinforced with ramie fibers and ramie weaving. Where the longer the immersion time, the greater the percentage of water absorption that occurs. This can be seen from the increase in the percentage value of water absorption from 0% to 3.14% (for 30 ppm salinity levels), 0.33% to 2.75% (for 40 ppm salinity levels) and 0.22% to 2.43. % (for salinity levels of 50 ppm) for 70 days of immersion. From these results, it can also be seen that the level of salinity can affect the percentage of water absorption, where the higher the level of salinity, the smaller the percentage of water absorption that occurs. This is because the salt contained in the water inhibits the water absorption process in the composite. The immersion of the composite panels in seawater affected the flexural strength of the composites which were reinforced with ramie weaving and ramie fibers. Where the reduction in the flexural strength of composites in ramie fiber composites was higher than ramie woven composites at the salinity of 30 ppm, 40 ppm, and 50 ppm, respectively 50.99%, 45.82%, and 44.14%. Likewise, the tensile strength of ramie woven composites and ramie fibers decreased in strength. The decrease in tensile strength of ramie fiber composites was higher than ramie woven composites at a salinity of 30 ppm, 40 ppm, and 50 ppm, respectively 43.61%, 56.14%, and 30.88%.