Recent thermoplastic composites have the potential to offer improved environmental tolerance, damage tolerance and decreased manufacturing cost compared with thermoset composites. However, it is difficult to impregnate the melted thermoplastic resin into reinforcement strands due to high viscosity of resin. Therefore, the laminate composite materials in which fiberous thermoplastic resin is coupled to the reinforcement strands have been developed. It is expected that the adhesive condition in micro interface of coupling laminate will be better, because there is thermoplastic resin in the orthogonal interface of reinforcement stands before the resin melt.
The purpose of this study was to estimate the adhesive condition of micro interface of the coupling laminate through immersion testing of the film stacked laminate under hot water environment. After immersion tests of water absorption, the mechanical properties, flexural modulus retention and flexural strength retention were determined. The degradation behaviors of coupling laminate and film stacked one were simulated by the finite element method with consideration for the degradation of constituent materials.
It was found that the material constants depended on water absorption under hot water environment by material testing and they were predicted quantitatively from classical Fick's diffusion equations. The numerical results were in good agreement with those of experiments under flexural conditions.
