Title: Vitrimers: Thermoplastic-Like Properties in a Thermoset Polymer for Fiber Reinforced Composites

Authors: Patricio Martinez, Steve Nutt

DOI: 10.33599/nasampe/s.24.0109

Abstract: "When compared to thermoset polymers, thermoplastics offer advantages, including formability, bonding, and recyclability. Standard thermosets cannot be re-shaped after cure; bonding typically involves adhesives or co-curing and cannot be reversed; and recycling is either mechanical, which damages fibers, or thermal which requires pyrolyzing the resin under extreme temperatures. Vitrimers are a type of thermoset polymer that also contain thermally reversible covalent bonds. Thus, they exhibit behavior similar to thermoplastics, and thus can be formed by heating with minor pressure. Vitrimer-to-vitrimer bonds can be formed using temperature and pressure. The matrix is fully recyclable, and fibers can be extracted with negligible damage. Furthermore, common thermoset composite manufacturing methods such as hot-press forming, resin transfer molding, and prepreg cure are all viable with vitrimers. This study showcases the variable thermoplastic-like properties of vitrimers. Parts were produced as neat resin, using RTM, prepreg, and a custom vitrimer-specific cured-ply forming. Neat resin parts were repeatedly reshaped, characterizing the mechanical properties of the material after multiple cycles, highlighting the retention of strength and flexibility after reprocessing: Tensile strength and elongation only dropped 38 and 45%, but only between cycles 12 and 21, with the properties remaining mostly constant before then. Short-beam shear strength was similarly observed dropping by upwards of 50% after 9 cycles. The vitrimer-specific cured-ply forming was revealed to be superior to standard prepreg cure procedures, resulting in void-free parts. The parts produced using RTM were used to highlight the lack of strength reduction from the recycling process. "

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Conference: SAMPE 2024

Publication Date: 2024/05/20

SKU: TP24-0000000109

Pages: 13

Price: $26.00