Influence of Temperature and Moisture on the Compressive Strength of Carbon Fiber Reinforced Polymers

The effect of moisture absorption and high temperature on the compressive strength of unidirectional IM7/977-2 carbon/epoxy resins have been investigated experimentally. The specimens were divided into 4 groups, and tested under 4 different conditions by varying the testing temperature and moisture parameters. The fiber orientation selected were 0 degrees, +/- 45 degrees and 90 degrees. The reported results showed that the compressive strength, fracture load and compressive modulus of the specimens were degraded under the influence of moisture absorption and high temperature. The largest compressive strength degradation was observed in the unidirectional specimens. Furthermore, the most severe case was noted for the specimens that were immersed in water and tested at 80 degrees C. The observed reduction in the strength varies depending on the fiber orientation, immersion time and test temperature. The results indicate the importance of considering environmental parameters in designing the composite structures for compression loadings.