Mechanical Properties and Recyclability of Fiber Reinforced Polyester Composites

Fiber reinforced polymer composites (FRPs) are valuable construction materials owing to their strength, durability, and design flexibility; however, conventional FRPs utilize petroleum-based polymer matrices with limited recyclability. Furthermore, fiber reinforcements are made from nonrenewable feedstocks, through expensive and energy intensive processes, making recovery and reuse advantageous. Thus, FRPs that use biobased and degradable or reprocessable matrices would enable a more sustainable product, as both components can be recovered and reused. We previously developed a family of degradable and reprocessable cross-linked polyesters from bioderived cyclic esters (l-lactide, delta-valerolactone, and epsilon-caprolactone) copolymerized with a bis(1,3-dioxolan-4-one) cross-linker. We now incorporate these networks into FRPs and demonstrate degradability of the matrix into tartaric acid and oligomers, enabling recovery and reuse of the fiber reinforcement. Furthermore, the effect of varying comonomer structure, catalyst, reinforcement type, and lay-up method on mechanical properties of the resultant FRPs is explored. The FRPs produced have tensile strengths of up to 202 MPa and Young's moduli up to 25 GPa, promising evidence that sustainable FRPs can rival the mechanical properties of conventional high performance FRPs.