Study into the Mechanical Properties of a New Aeronautic-Grade Epoxy-Based Carbon-Fiber-Reinforced Vitrimer

Abstract

The current drive for sustainability demands recyclable matrices for composite materials. Vitrimers combine thermoset properties with reprocessability, but their mechanical performance in highly loaded applications, for instance, composites for aeronautics, is still to be demonstrated. This work presents the complete mechanical characterization of a new vitrimer reinforced with carbon fiber. This vitrimer formulation consists of functional epoxy groups and a new dynamic disulfide crosslinks-based hardener. The testing campaign for the vitrimer composites encompassed tension, compression, interlaminar shear strength (ILSS), in-plane shear (IPS), open-hole tension (OHT) and compression (OHC), filled-hole compression (FHC) and interlaminar fracture toughness tests under mode I and II. Test conditions included room temperature and high temperature of 70 °C and 120 °C, respectively, after moisture saturation. Tension and flexural tests also were applied on the neat vitrimer resin. The results compared well with those obtained for current aeronautic materials manufactured by Resin Transfer Molding (RTM). The lower values observed in compression and ILSS derived from the thermoplastic veils included as a toughening material. This work demonstrates that the vitrimer formulation presented meets the requirements of current matrices for aeronautic-grade carbon-reinforced composites.

Exploring the Limits of High-Tg Epoxy Vitrimers Produced through Resin-Transfer Molding

“…Although it is an interesting property for certain applications, it becomes crippling in the context of aeronautical specifications. From a composite manufacturing process point of view, although a few papers reported vitrimer composites produced by RTM, ,− none of them studied completely the cross-linking kinetics and reactivity with a time–temperature–transformation (TTT) diagram and the optimization of the process parameters and curing cycles. TTT diagrams , were developed in the mid-1980s and widely used for thermosets, but were never reported for vitrimer materials, to the best of our knowledge.…”

High‐Performance Vitrimeric Benzoxazines for Sustainable Advanced Materials: Design, Synthesis, and Applications

“…[ 28 ] Many epoxy vitrimers have since been reported, featuring excellent properties. [ 29–77 ] Other reported vitrimers are based on polybutadienes, [ 78–82 ] polyurethanes, [ 83–99 ] polyhydroxyurethanes, [ 100,101 ] polyurethane urea, [ 102,103 ] polyesters, [ 104–115 ] polycarbonates, [ 116 ] and polyimides. [ 117,118 ] These materials have low‐to‐medium‐to‐high glass transition temperatures, with polyimide vitrimer achieving T g of 274 °C and a 5% weight loss temperature of 429 °C.…”

Vitrimer composites: current status and future challenges

“…Earlier this year, Builes Cárdenas et al reported the study of a low viscosity epoxy resin/aromatic disulfide hardener formulation especially designed for aeronautics and RTM processes. The report was mainly technical and the mechanical properties of the CFR epoxy vitrimer presented were comparable to those of reference CFR epoxy thermosets 107.…”

“…The report was mainly technical and the mechanical properties of the CFR epoxy vitrimer presented were comparable to those of reference CFR epoxy thermosets. 107…”