# Modified SC Resin Pre-Coating Treatment for Rapid and Robust Repair of CFRP Laminates with Sharp Delamination Cracks

## TL;DR

A new resin coating method repairs carbon fiber composites quickly and effectively, restoring their strength to nearly original levels.

## Contribution

A self-curing resin pre-coating solution with carbon nanotubes enables rapid and robust repair of CFRP laminates.

## Key findings

- The modified SC-RPC solution reduced repair time from 2–3 months to just a few hours.
- CFRP specimens repaired with SC-RPC+CNT achieved full restoration of compressive strength and load-bearing capacity.
- The method effectively addresses subsurface delamination cracks through capillary action.

## Abstract

A recent composite technique, namely Resin Pre-Coating (RPC), has demonstrated remarkably high effectiveness in the repair of Carbon Fiber-Reinforced Polymer (CFRP) composites. Compared to widely used scarf repair and injection repair, this non-destructive method offers advantages in addressing subsurface damages from the millimeter to micron scale, such as edge delaminations that frequently occur due to machining or low-energy impacts. The acetone-rich RPC solution can spontaneously transport sticky resin and other toughening agents into defects through capillary action. In this study, we further improved the solution by adopting a self-curing resin (i.e., SC-RPC), reducing the repair duration from the initial 2–3 months to merely a few hours. Using this modified solution, the CFRP specimens prepared containing delamination cracks were largely restored, reaching up to 94.9% of the original compressive strength. With the additional incorporation of carbon nanotubes (CNTs), full restoration was achieved, as is evidenced by load-bearing capacities and overload failure modes comparable to those of pristine specimens. The findings of this study may help alleviate concerns regarding substandard post-repair performance and prolonged repair durations, which are frequently criticized in real-world CFRP maintenance projects. The preparation of two new formulations, SC-RPC and SC-RPC+CNT, along with the optimization of key parameters, was carefully detailed in the manuscript to ensure experimental reproducibility.