Exploring the repairing capabilities of high-performance glass fiber reinforced vitrimer composites

Vitrimers represent a class of polymers featuring dynamic covalent crosslinks that can undergo dynamic network rearrangements and hold a notable promise as recyclable thermosets with crack-healing capabilities. In particular, vitrimers with aromatic disulfide hardeners have emerged over the past few years. In these high-glass-transition polymers, the healing regime coincides with the onset of thermal degradation, posing a fundamental challenge for reconciling adequate network mobility with thermal degradation prevention. Therefore, the present study explores the repair capabilities of glass fiber-reinforced polymers (GFRP) with a vitrimer matrix to understand how the interplay of temperature, time, and pressure affects the repair. A transferable framework for estimating a favourable time-temperature regime for vitrimer healing is introduced, based on thermal degradation and dynamic bond-exchange kinetics. The suggested optimized conditions are applied to repair different GFRP samples subjected to quasistatic intralaminar crack opening, and the extent of apparent mechanical property recovery is used to assess the repair effectiveness. Pressurized reconsolidation is required to restore the microstructure and repair cracks. When applying the prescribed repair conditions to the specific damage in short-beam samples, remarkable stiffness and strength recovery ratios of 93 % and 80 %, respectively, are achieved. Conversely, deviations from the prescribed regime due to improper dwell temperatures and times considerably reduce the recovery ratios of mechanical properties, limiting them to their residual values. However, the double cantilever beam repair conducted within the favourable regime shows that repair effectiveness depends strongly on the fracture surface morphology, revealing inherent limitations in the repair capabilities of the investigated laminate system. • Quantifying the effect of thermogravimetric degradation within the dynamic-bond exchange regime on the deterioration of mechanical performance. • 2.5 % thermogravimetric degradation causes a deterioration of mechanical performance (40 % loss in strength, 13 % loss in T g ) of the vitrimer resin. • Processing maps link thermal histories to repair efficiency and thermogravimetric degradation during GFRP repair. • Optimized repair conditions yield excellent short beam stiffness and strength recovery of 93 % and 80 %, respectively. • Demonstration of non-transferrable repair efficiencies for different damage modes and fracture surface morphology.