Sustainable composite manufacturing from non-expiring carbon fiber/epoxy prepregs based on a vitrimeric matrix

Abstract

Despite the benefits of manufacturing composite materials from prepregs, its use is nowadays limited to high-production rate industries due to the high costs associated with their limited shelf life. Once this time passes, the material is considered as expired and disposed of as a non-usable waste. To avoid shortening its shelf life, prepregs are stored in refrigerators, increasing energy consumption, and thus magnifying the negative environmental impact. For this reason, the objective of this paper is to develop a new lifelong prepreg material without an expiration date that can be consolidated as a laminate after surpassing the gelation time of the resin, thus allowing composite materials processing technology based on prepregs without the need of freeze storage. To prove this concept, the study is carried out using a vitrimeric resin composed of an epoxy monomer (DGEBA) and 2-Aminophenyl disulfide (AFD) as a hardener. Two prepregs are manufactured and stored for 30 days at different conditions: environmental conditions, considered as the aged or non-conventional prepreg; and at −18 °C in a freezer, to replicate the conventional prepreg conditions. The results of the cured composites show stable glass transition temperatures and curing degrees between the two laminates. Concerning the mechanical properties, it has been proved that the gelation phenomenon of the non-conventional prepreg does not have any negative effect, showing a 11 % and a 21 % improvement of the flexural strength and failure strain, respectively, together with a 10 % increase of the interlaminar shear strength (ILSS) in comparison with the conventional prepreg, proving the potential of the proposed sustainable prepregs.