纤维聚合物复合材料的有效湿扩散系数

根据纤维聚合物复合材料的微观结构, 建立了基于复合材料单胞模型的湿扩散计算方法, 研究了不同温度和不同体积分数下纤维聚合物复合材料的湿扩散性能。假设纤维是不可渗透的, 并在聚合物基体中均匀分布, 计算了不同温度不同体积分数下复合材料的有效湿扩散系数。结果表明: 复合材料的有效湿扩散系数随温度的升高而增大, 随纤维体积分数的增大而减小； 在相同温度、 相同体积分数下, 正六边形排列的纤维复合材料的湿扩散系数比正方形的略大。计算结果及经验公式与Gueribiz曲线基本一致, 说明用单胞模型计算复合材料的湿扩散性能是非常有效的, 有助于理解纤维复合材料的湿扩散机制和性能。 

Effective moisture diffusion coefficient of fiber polymer-matrix composite

To determine the effective moisture diffusion properties of fiber polymer-matrix composites, a new solution method was established by using a concept of unit cell. The effects of temperature and fiber volume fraction on the effective moisture coefficients were investigated. In this study, the impermeable fibers were assumed to be distributed uniformly in matrix. Using the proposed model, effective moisture diffusivities were calculated at different temperatures and fiber volume fractions. The results show that effective diffusivities of the composites increase with the increase of temperature, and decrease with the increase of fiber volume fraction. Effective diffusivities of regular hexagonal composite are a bit larger than those of square one under the same temperature and volume fraction. The numerical results are compared with those from empirical formula, and good agreement is achieved. Therefore, it proves that the present method is valid and reliable to predict moisture diffusion properties for fiber polymer-matrix composites by the unit cell model. The present results are significant to explore moisture diffusion mechanism and overall properties of composites.