Synthesis, characterization, and recycling of bio-derivable polyester covalently adaptable networks for industrial composite applications
Chen Wang, Avantika Singh, Erik G. Rognerud, Robynne E. Murray, Grant M. Musgrave, Morgan Skala, Paul Murdy, Jason S. DesVeaux, Scott Nicholson, Kylee Harris, Richard B. Canty, Fabian Mohr, Alison J. Shapiro, David Barnes, Ryan Beach, Robert D. Allen, Gregg T. Beckham, Nicholas A. Rorrer
Abstract
Fiber-reinforced polymers (FRPs) are critical for energy-relevant applications such as wind turbine blades. Despite this, the end-of-life options for FRPs are limited as they are permanently cross-linked thermosets. To enable the circularity of FRPs, we formulated a bio-derivable polyester covalently adaptable network (PECAN), sometimes referred to as a polyester vitrimer, to manufacture FRPs at >1 kg scale, which is accomplished as the resin is infusible (175–425 cP at 25°C viscosity), can be cured at 80°C within 5 h and is depolymerizable via methanolysis yielding high-quality fibers and recoverable hardener. The FRPs exhibit a transverse tensile modulus comparable with today's wind relevant FRPs (10.4–11.9 GPa). Modeling estimates a resin minimum selling price of $2.28/kg and, relative to an epoxy-amine resin, PECAN manufacture requires 19%–21% less supply chain energy and emits 33%–35% less greenhouse gas emissions. Overall, this study suggests that redesigned thermosets can yield beneficial circularity.