超輕量 纖維强化 複合材料의 物理的/機械的 特性評價를 통한 吸濕 메커니즘의 究明

Abstract

When FRP(Fiber Reinforced Plastics) is exposed to the water/moisture environments, the mechanical properties of FRP could be decreased irreversibly. The major reason for the degradation of FRP in the moisture environments is that the absorbed water/ moisture make their glass transition temperature lowered, and the water/ moisture, also, directly influence their debonding or delamination. As a result, the mechanical properties, such as strength, stiffness, and thermal resistance properties could be lowed. Moreover, the degradation rates of the FRP were directly influenced by the exposed term in the moisture environments, moisture contents of the FRP. Moisture contents of the FRP relate to temperature, relative humidity, moisture equilibrium of the environments, exposed surface area, resin contents and diffusivity of the material. The decreased strength and stiffness of the material are directly related to their moisture contents. The focus of this study is to find out the degradation mechanisms and degradation/ recovery behaviors of FRP in the moisture environments. 3 steps of moisture absorption mechanisms were developed in the study. Moreover, moisture absorption and degradation behaviors of the FRP specimens were monitored periodically. Fractography and transverse section of FRP specimens also were observed to find out debonding/delamination of the specimens by moisture/water absorption. Moreover, diffusion coefficients of the FRP specimens were deduced to analysis the absorbed moisture degrees of the FRP by numerical values. It could be help to material designer/consumer as this study indicated the minimization methods of FRP in the moisture environments by moisture absorption mechanisms which were clarified in this study.