The diffusion of oxygen through uniaxially and biaxially drawn polypropylene

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Abstract

The oxygen permeability of uniaxially and biaxially drawn polypropylene has been studied for both film and tube samples. With few exceptions the permeability coefficient decreases on drawing, but effects are small, particularly for biaxially drawn material where the coefficient does not fall below about 60% of the isotropic value. Molecular orientation as indicated by refractive index measurements appears as a major cause of the reduction in permeability.

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