Influence of Moisture Content on the Transverse Strength of Different Unidirectional Carbon/Epoxy Laminates

摘要

Tensile tests were performed at room temperature, at 333 K and 358 K on 90 deg composite laminates (T300/Narmco 550, T300/code 92 and T300/code 69) after 264 hr immersion in water. The theory of moisture absorption using Ficks law of diffusion was reviewed. Water absorption was measured by weighing and electrical resistance measurements. Maximum moisture content for Code 92, Code 69 and Narmco 550 laminates was 1%, 1.75% and 3.05%, respectively. Measurement of the electrical conductivity appeared to be a quick method to check the moisture content of Code 69 and Narmco 550. The tensile strength of the Code 92 and Narmco 550 laminates strongly depended on the moisture content. Code 69 laminates are superior in strength to Narmco 550 and Code 92 laminates in the temperature range of 320 K to 360 K. Since no influence of moisture content on the fracture strain was observed, the reduction in fracture strength with increasing moisture content is essentially connected with a decrease of the modulus of elasticity.