Structural and performance changes in polyester yarn brought about by simultaneous draw texturing processes

A partially oriented yarn of polyester has been subjected to the simultaneous draw texturing process and also drawn on the same machine without false twist. The effect of the variation of the applied draw ratio, the temperature of the first heater, the speed of the yarn, and (for textured yarn) the twist on the properties of the processed yarns was investigated. It was shown that the main factor affecting the properties is the applied draw ratio, the other factors having only a secondary influence, which is different from the findings with conventionally textured yarn. A tentative model for the polyesters based on fibrillar units with extended chains is proposed to account for the observed changes.