The Effects of Long-Term Exposure of Flax Fiber Reinforced Polymer to Salt Solution at High Temperature on Tensile Properties

Most research on natural fiber composites has been primarily conducted on randomly-oriented fibers. This study is focused on the short-and long-term performances of flax fiber-reinforced polymer (Flax-FRP) made from continuous unidirectional fiber mats, and compares it to Glass-FRP composite. The study looked into the effect of number of layers on properties, comparing wet layup (WL) to vacuum bag (VB) molding, and aging in a 3.5% salt solution for up to 365 days at 23, 40, and 55 degrees C. Results show that Flax-FRP has a tensile strength and modulus of one third the values of Glass-FRP. Using the VB process, Flax-FRP showed a strength and modulus 18 and 36% higher, respectively, than WL specimens. As the number of layers increased from one to five, the strength and modulus also increased but stabilized at three layers. After 365 days of conditioning at 23, 40, and 55 degrees C, WL specimens showed a strength retention of 81, 73, and 69%, respectively. Using the Arrhenius relationship, it was estimated that both WL and VB Flax-FRP would retain 60% of their tensile strength after 100 years of saltwater exposure at an annual mean temperature of 10 degrees C. (C) 2015 Society of Plastics Engineers