The effect of stress on the diffusion of water in glassy polymers is analytically treated. Utilizing the free volume concept the effect of stress on the free volume fraction is established and in turn is related to the diffusion coefficient yielding the following formula: Dσ = Doe(6 to 10)σ/G where Dσ and Do are the diffusion coefficients in the presence and absence of stress respectively, G is the shear modulus, and σ is the stress. Experiments are described which demonstrate that in a bent epoxy bar, more water is picked up at the tension side than at the compression side. Theory and experiment are discussed and compared.

Glasses containing 50 to 75 mo% SOz and up to 35 mol% ZnO were studied using thermal expansion, density, molar volume, refractive index, molar refractivity, internal friction, and infrared absorption data. Increasing the zinc oxide content in the glasses decreased the thermal expansion and increased the density, refractive index, and the activation energy for the alkali-ion diffusion internal friction peak. Infrared absorption from 1500 to 70 cm-' indicated the presence of both six and four oxygen coordination for the zinc cation.

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