STP452

    Effect of Water on Glass Fiber-Resin Bonds

    Published: Jan 1969


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    Abstract

    The strength realized in a composite depends in part on its ability to arrest its nascent flaws and cracks. A theory for glass fiber-resin bonding is developed based on a restrained resin layer in the interphase region, an interfacial mechanism for resistance to crack penetration through the glass surface, and the segregation of resin-glass bonds of a strong, hydrolysis-resistant type to the alkali-free, silica “islands” on the glass surface.

    In well-bonded glass fiber-resin composites, the initial effects of water are to stiffen the interphase resin layer and to create a pressure at the interface through the formation of water pockets on the glass surface. Stiffening the resin interphase layer weakens its ability to absorb the stress of a crack tip penetrating from the resin to the interface, thereby lowering composite strength resistance. The long term effect of the water layer is twofold. It creates a pressure tending to pry off the resin layer from the silica islands. It also furnishes a reservoir for the solution of aqueously soluble ions, that is, it acts to dissolve certain of the silicate areas and undermine the silica islands and thereby break the glass-resin bonds from the glass filament mass.

    Keywords:

    composites, solid mechanics, glass fibers, crosslinking, polymers, bonding, effect of water, interfaces, interphase region, crack propagation, restrained resin layer, water films, aqueous attack, unsaturated polyester, epoxy, E-glass, evaluation, tests


    Author Information:

    Eakins, W J
    Consultant, South Woodstock, Vt.


    Paper ID: STP44704S

    Committee/Subcommittee: D30.04

    DOI: 10.1520/STP44704S


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