The Recyclability of a Flax Fiber Reinforced Polymer (FFRP) Composite

• Megan Malherb, Civil Engineering, University of South Carolina

• Jovan Tatar, Civil and Environmental Engineering, University of Delaware

Natural fiber reinforced polymer composites exhibit desirable properties for civil infrastructure such as strength-to-weight ratio, durability, and sustainability. With a growing market for composites and rising waste concerns, it’s imperative to find a renewably sourced and recyclable solution. This study assessed the recyclability of a flax fiber reinforced polymer (FFRP) composite fabricated with a covalent adaptable network (CAN) matrix. After exposing the FFRP composite to a solvent of dimethylformamide and 2-mercaptoethanol, the disulfide bonds in the matrix were cleaved allowing for the flax fabric to be extracted. The tensile strengths and elastic moduli of FFRP composites manufactured with virgin and recycled flax fabric were evaluated following the ASTM standard. Tensile testing was also performed to obtain the stiffness and breaking force of the virgin flax fabric, flax fabric exposed to the solvolysis chemicals, and flax fabric extracted from the matrix. Scanning electron microscopy (SEM) was employed to assess the surfaces of the flax fabric samples. The composites manufactured with recycled flax fabric showed a 72% retention in tensile strength and a 76% retention in primary and secondary moduli. Tensile testing of the three flax fabric test groups showed negligible changes in stiffness. SEM images of the flax fabric surfaces revealed residue left behind by both the resin and solvolysis chemicals. These results give insight into the feasibility of using recycled flax fabric in composites and begin to demonstrate the effects of chemical processing on the flax fibers.