Interlaminar repairing and thermoforming properties of carbon fiber reinforced Vitrimer epoxy resin composites

Abstract

The interlaminar repairing behavior and thermoforming capacity of new carbon fiber reinforced Vitrimer epoxy resin (V-CFRP) composite and corresponding mechanisms were studied. The results reveal that the glass transition temperature (Tg) of the new Vitrimer epoxy resin is 92.8 ℃, and it exhibits significant stress relaxation behavior at temperatures higher than Tg. The stress relaxation time exhibits a linear relationship with temperature; The hot-press repair behavior and thermoplastic molding ability of V-CFRP composites were studied using a three-point bending experiment. The hot-press repair study shows that hot pressing at 180-220 ℃ for 1.5-2.0 h and 5 MPa can achieve nearly 100% repair of interlaminar damage in the composite; The bending modulus and bending strength of V-CFRP composites is decreased by more than 80% after pre-heating at 180-220 ℃ for 5-30 min. The significant decrease of bending modulus means that V-CFRP composite is suitable for thermoforming process. Moreover, a V-CFRP part with three-dimensional structure is successfully prepared by thermoforming process under the conditions of 200 ℃, 5 MPa and 2 h, which confirms the thermoforming capacity of V-CFRP composites.

Keywords

• vitrimer
• carbon fiber reinforced composite
• interlayer repairing
• thermoforming process
• ester bond exchange reaction