Interface-driven damage analysis in carbon fibre/epoxy composites : mitigation via a novel continuous microwave-grown CNT interphases

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Li, Rui and Yang, Xuqi and Zhang, Ze and Wang, Kaitao and Li, Yixiao and Shabestari, Marjan Entezar and Lotfian, Saeid and Kalali, Ehsan Naderi (2026) Interface-driven damage analysis in carbon fibre/epoxy composites : mitigation via a novel continuous microwave-grown CNT interphases. Engineering Failure Analysis, 195. 111009. ISSN 1350-6307 (https://doi.org/10.1016/j.engfailanal.2026.111009)

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Abstract

Carbon fibre epoxy composites are commonly not damage-tolerant due to the nearly smooth fibre surface, which leads to interface debonding and low energy absorption during impact. In this study, we present a Continuous microwave-assisted route to graft CNTs onto carbon fibre tows and form Barbed-like hierarchical interphases for scalable composite toughening. A lab-scale microwave-based system with a quartz reactor vessel is suitable for continuous CNT growth: stacked catalyst-coated carbon fibre bundles are pulled through a controlled zone of microwave irradiation (800 W, 10–40 s) within a stream of nitrogen and nebulised hydrocarbon feed. The process conditions, such as hydrocarbon flow rate and catalyst composition, were adjusted to achieve a dense, uniform, and interwoven CNT coating on the fibre surface. The formed CNT grafted fibres (CNT@CF) provide distinct mechanical advantages to the epoxy. The 5 wt% loading of CNT@CF enhances tensile strength and modulus from 7.2 MPa and 22.3 GPa for pristine CF to 11.9 MPa and 31.4 GPa, respectively. The CNT@CF/epoxy composite with 10 wt% loading possesses an elongation at break of 4.5% and impact strength of 24.4kJ/m2, much higher than those (1.3%, and 3.8 kJ/m2) for neat epoxy. Fractographic observations reveal diminished pull-out of the fibres and prominent crack-bridging entities, which are indicative of a Barbed-like physical interaction that improves mechanical locking and stress transmission. The present work illustrates a feasible CNT@CF Continuous manufacturing approach and emphasises an interphase-driven pathway to impact-toughened hierarchical composites.

ORCID iDs

Li, Rui, Yang, Xuqi, Zhang, Ze, Wang, Kaitao, Li, Yixiao, Shabestari, Marjan Entezar, Lotfian, Saeid ORCID logoORCID: https://orcid.org/0000-0001-8542-933X and Kalali, Ehsan Naderi;
CORE (COnnecting REpositories)