The Structure and Moisture Stability of the Matrix Phase in Glass-Reinforced Epoxy Composites

Immersed Fatigue Performance of Glass Fibre-Reinforced Composites for Tidal Turbine Blade Applications

“…Water is detrimental to the strength of naked (unsized) glass fibres due to the occurrence of stress corrosion cracking (SCC). This occurs when water molecules migrate to the tip of cracks or flaws on the surface of glass that is under stress and accelerate the cracking process [17]. The silane-coupling agents mentioned earlier were developed with an ability to bond strongly to the glass fibre surface and this reduces the interaction of moisture with the glass, preventing or reducing SCC in humid atmospheres.…”

“…Interlaminar shear strength (ILSS) and 45°off-axis tests are used as an indication of changes in interface bond strength and tests on GFRP laminates have shown reductions of 8 to 37 % after ageing in room temperature water [3,16]. Studies have shown that most of the bond strength recovers upon redrying the composite material, particularly when the initial loss in bond strength was due to high temperature ageing [3,17].…”

“…Barrier layers may also suffer from either abrasion by sand and grit suspended in the water or from surface cracking at strain levels likely to be experienced by marine renewable energy devices. Finally, it should be noted that it is very difficult to produce a barrier that can actually prevent diffusion of the small amount of moisture (1-2 %) required to saturate GFRP over the [10][11][12][13][14][15][16][17][18][19][20] year lifetime of these devices. Certainly the standard isophthalic polyester gelcoat is not capable of this level of performance [3].…”

Fiber-reinforced polymer (FRP) composites in environmental engineering applications

“…The durability response of composites is identifi ed typically in terms of chemical, physical, and mechanical aging and their combinations, which depends primarily on pH level, temperature, creep/relaxation, UV radiation, and externally induced thermomechanical stress fl uctuations. The durability response is further accelerated in the presence of water or salt solutions because of their expansion under freezing (ACI, 2006;Chin et al, 2001;Karbhari, 2006;McBagonluri et al, 1998;Antoon and Koening, 1980). In terms of the above parameters, fl uid absorption in and out of composites under freeze-thaw conditions has the highest infl uence on durability .…”

“…The rate of degradation of polymer composites exposed to a fl uid environment is related to the rate and quantity of fl uid sorption (Bott and Barker, 1969), which are governed mostly by: chemical structure of the resin; degree and type of crosslinking; state of the material including void content; type, temperature, and concentration of fl uid; and applied stress and hydrostatic pressure (Antoon and Koening, 1980). Exposure of composites to moisture and chemicals causes stress corrosion, which is driven by the exchange of alkali ions in glass fi bers and hydrogen ions from a reactive fl uid, leading to spontaneous fi ber surface cracking and stress failure (Price, 1989).…”