Moisture Distribution Profiles in RT-Cured Glass/Epoxy Laminates of Different Thicknesses

Abstract

Investigations were carried out on the moisture absorption behavior of RT-cured glass/epoxy composite specimens subjected to 333 K/Immersion in distilled water. Different laminate thicknesses (i.e., 0.25-2.25 mm) were studied for comparative evaluation of their moisture diffusion and distribution profiles across the thickness of the composite as a function of the exposure period.

Moisture absorption data showed that the equilibrium moisture levels (M_m) remained practically the same for different laminates of the same fiber weight fraction (i.e., 0.62). Further, the times of saturation (t_m) increased with the laminate thickness, while the absorption rates (slopes of the absorption curves) showed a reverse trend.

It was also found that the Diffusion Coefficient (D_c) values of different thicknesses specimens ranged between 0.28 and 7.81(10 ⁷)mm²/sec, indicating a negligible thickness effect on this diffusion parameter. The small variations of D_c (all of the order 10 ⁷ mm²/sec) are attributed mainly to the variations in the edge areas for different thickness laminates.

Keywords

glass/epoxy composite laminate thickness moisture gain diffusion coefficient time of saturation moisture distribution

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