Bond exchange reactions as a paradigm for mitigating residual stress in polymer matrix fiber composites

TL;DR

This paper explores the use of vitrimers with bond exchange reactions to reduce residual stresses in polymer matrix fiber composites, combining experimental fiber measurements and computational modeling.

Contribution

It introduces a novel approach using vitrimers with stress alleviating bond exchange reactions to mitigate residual stress in fiber composites.

Findings

Vitrimers with catalysts significantly reduce fiber strain during curing.

The developed model accurately simulates stress evolution in composites.

Bond exchange reactions can effectively mitigate residual stress.

Abstract

Polymer matrix fiber composites often suffer from residual stresses due to differences in coefficients of thermal expansion between the fibers and resins, as well as contractile strain of the resins during curing. To address residual stress driven composite failure, we propose the use of vitrimers as composite resins, which can undergo thermally activated, stress alleviating, bond exchange reactions (BERs). We conduct fiber Bragg grating measurements for a single glass fiber within bulk vitrimer. These show that the fiber strain in vitrimers with 5% catalyst is significantly lower than in those with 0% catalyst (minimal BER expected) during both curing and post-curing phases. We developed a finite deformation, micromechanically-inspired model that incorporates curing, thermal processes, and BERs, and then implemented this model it into finite element software to simulate stress evolution within single fiber composite systems. The combination of experimental and computational results reveals that BERs can effectively mitigate, but not eliminate, the residual stress in polymer matrix fiber composites.