Study of the water absorption and its influence on the Young’s modulus in a commercial polyamide

Abstract

The water absorption and desorption processes of a commercial polyamide were studied in the temperature range of 20-90 °C. A strong influence of the temperature on the water mass saturation, primarily in the region of the glass transition temperature, was observed. Differences in the parameters related to the diffusion process were also observed between samples with different thicknesses. The results were analyzed using the Langmuir model, which considers two states of absorbed water in the polymer: bound and mobile. The obtained diffusion coefficients were analyzed in terms of the temperature and the state of the polymer, either glassy or rubbery. The influence of the absorbed water on the Young's modulus was evaluated using the impulse excitation technique. It was observed that the water absorbed in the bound state generates the most significant changes in the Young's modulus.