High-Performance Vitrimer Entailing Renewable Plasticizer Engineered for Processability and Reactivity toward Composite Applications
Niklas Lorenz (TU Delft - Group Kumru)
William E. Dyer (TU Delft - Group Kumru)
Baris Kumru (TU Delft - Group Kumru)
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Abstract
The present article introduces a high-performance epoxy vitrimer to target structural composite applications. By utilizing a reactive diluent derived from biobased feedstock, the maximum glass transition is tailored to maintain a sufficient temperature window for reprocessing, avoiding the degradation of permanent bonds. Different fractions of permanent cross-links are imbued into the network structure, and the hybrid network is elucidated by creep and stress relaxation. The creep behavior at service temperatures below 150 °C remains unaffected, while slower bond exchange dynamics and higher extrapolated topology freezing temperatures Tv are reported for an increasing number of permanent cross-links. Comprehensive studies of physicochemical, thermo-rheological, and curing reactions are carried out and summarized in a conversion-temperature phase diagram first reported for a vitrimer. The vitrimers show great malleability, even with permanent cross-link fractions above the theoretical limit for a percolated network formation, and we demonstrate recycling by comminuting and subsequent reconsolidation. These findings provide valuable guidance for enhancing material and process development of high-performance vitrimer resins and lay the groundwork for advancing composites built on vitrimer matrix systems.
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