Sizing and Desizing Polyester / Cotton Blend Yarns Using Liquid Carbon Dioxide

We report a preliminary investigation of nonaqueous sizing and desizing where liquid carbon dioxide is the solvent. New size formulations are required for this process because traditional size materials are not directly soluble in liquid carbon dioxide. Candidate size compounds are first tested for solubility, and those found to be soluble are then applied to polyester/cotton yarns using two methods: immersing the yarn in a size-saturated carbon dioxide solution and drawing the yarn through a hot melt of the compound. The tensile strength and elastic modulus of the sized yarns are deter mined. Complete removal of the size compounds from the treated yarns by means of liquid carbon dioxide extraction is demonstrated.