Water permeation through novel marine composites

Mackay, Paul (1998) Water permeation through novel marine composites. (MPhil thesis), Kingston University, .


An investigation into the water permeation characteristics of marine laminates, based on epoxy resins has been undertaken using a simple gravimetric method. The effect of commercial, non-metallic barrier systems (coatings and films), in conjunction with minor mechanical damage, on the water transmission rate (WTR) of water through the composite materials has been assessed. Moisture barriers effectively reduce the steady-state water transmission rate (SS- WTR). Laminates incorporating an impermeable reinfo~cing fibre (glass, Dyneerna or their hybrid combination) performed significantly better than laminates reinforced. with hygroscopic Kevlar fibres. ATH fire retardant reduced SS- WTR at lower temperatures, but at higher temperatures the performance was significantly reduced. The effectiveness of the moisture barriers became more noticeable at higher temperatures. Minor mechanical damage such as impact and abrasion affects the integrity of the coatings. The moisture barrier treated laminates performed markedly better than untreated materials on cyclic loading. Water uptake curves for the untreated, undamaged laminates indicated non-ideal Fickian diffusion, although positive deviation in the initial portion of the Dyneerna fibre laminate curves indicated dual-mode, Langmuirian diffusion. Diffusion coefficients were calculated and found to follow the same trend as the SS- WTR suggesting that the water transmission was a diffusion controlled process.

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