An analysis of the moisture‐related properties of hydrolyzed polyester

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Abstract
Alkaline hydrolysis causes pitting of the surface of polyester (PET) fibers and films and improves their wettability, as indicated by contact angle measurements. The enhanced wettability is due to an increase in either the number or the accessibility of polymer hydrophilic groups to water and/or an increase in the roughness of sample surfaces. The increase of void space in the PET yarn and fabric structure, induced by treatment in aqueous NaOH together with the increased wettability of the fibers, was effective in improving the moisture transport properties of the materials. The NaOH‐treated PET fabrics transported the water further than isolated corresponding yarns, possibly because, in the fabrics, the spaces between the yarns acted as an additional reservoir that permitted further wicking to occur. It is apparent from immersion and equilibrium wicking capacity tests that a hydrophilic topical finish, as well as a change in the yarn/fabric structure and the hydrophilicity of their surfaces can increase the water holding capacity of PET fabric. The moisture regain and water retention values of the samples were determined, and it was found that such tests are not sufficiently sensitive to distinguish between the hydrophilicity of nontreated PET fabrics and that of PET fabrics modified either by application of a topical finish or by NaOH treatment.