Moisture absorption characterization of carbon fiber‐reinforced polymer using Fickian and non‐Fickian models

Abstract

AbstractThree classic moisture absorption models including the Fickian model, the Langmuir and the time‐variable diffusion model were adopted to describe the absorption behavior of carbon fiber‐reinforced polymer (CFRP) laminates in this work. A new non‐Fickian model based on the two‐phase absorption rule was proposed by introducing the equivalent absorption time into the Langmuir model. Experiments of accelerated moisture absorption were conducted for CFRP laminates with different lay‐ups under three temperatures. Moisture uptaking performance of the CFRP laminates was discussed. Preliminary data analysis of the moisture absorption content showed the existence of non‐Fickian diffusion behavior. Four numerical models were implemented into Matlab by combining the Gauss‐Newton algorithm with minimum mean square error. Effects of the environment temperature and the lay‐ups of the laminates on the diffusion process of water molecules in CFRP. The results demonstrated that the modified time‐variable Langmuir model shows the best fitting performance. The diffusion coefficient and equilibrium moisture uptake increased with the environment temperature. Water diffusion coefficients in monotonous ply‐structure is larger than that in multi‐angle plys.