When carbon fiber-reinforced epoxy composite laminates are exposed to moisture, the epoxy matrix absorbs water molecules, causing it to swell and soften. This swelling can lead to the formation of micro-cracks within the matrix, which can then propagate and cause delamination between the layers of the laminate. Delamination is a critical failure mode in composite laminates, as it significantly reduces the laminate's strength and stiffness.
In addition to causing delamination, moisture can also degrade the carbon fibers themselves. Water molecules can penetrate the fiber surface and react with the carbon atoms, leading to the formation of corrosion products. This corrosion can reduce the fiber's strength and stiffness, further contributing to the laminate's failure.
The failure of carbon fiber-reinforced epoxy composite laminates when wet is a complex process that involves several mechanisms. Moisture absorption, matrix swelling, micro-cracking, delamination, and fiber corrosion are the key factors that contribute to the failure of these laminates in wet environments.
To improve the moisture resistance of carbon fiber-reinforced epoxy composite laminates, various techniques can be employed, such as adding moisture barriers, using hydrophobic resins, and applying protective coatings. By preventing moisture ingress and mitigating its effects, the durability and performance of these laminates in wet environments can be significantly enhanced.
