Effect of Additives on the Structure of Melt-Spun Poly(ethylene Terephthalate)

Incorporating a small amount of comonomer, sodio sulfoisophthalate, in PET produces a sharp decrease in the orientation of melt-spun fibers, but also reduces the wind-up-speed at which crystallization occurs in the spinline. This is consistent with high variations in local orientation, with crystallization in those areas where orien tation is sufficiently high. Incorporating a very small amount of an agent that ac celerates melt crystallization under quiescent conditions has no effect on spun yarn structure, because crystallization in the spinline is dominated by orientation/stress phenomena