Winding speed of PBT filament production

As there are more methylene exists in PBT main chain structure,it makes the forces weaken between the molecules and leads to the low glass transition temperature,extremely be easy to crystallization.So when spinning forming,the crystallization,orientation of nascent fiber have obvious changed along with the changing of spinning speed,at the same time,it produces shrinkage and relaxation when the package forming.Experiments show that with the increase of spinning speed,birefringence and crystallinity of PBT nascent fiber has increased significantly.Meanwhile,when the spinning speed is less than 900 m/min,package forming has a difficulty,and package forming is better with the increase of spinning speed. the forming is good when spinning speed is 1100 ~ 1200 m/min.

This may be because the spinning speed is less than 900 m/min,the macromolecular chain of nascent fibers amorphous area is active,creep effect is remarkable,crystal area orientation is bad,the internal stress of fiber molecular chain is lesser,regarding crystallization arrangement for predominance position when storing,it makes molecules along the axial elongation.The lower the spinning speed,the effect is more obvious.But when the spinning speed is higher than 2500 m/min,also appear bad phenomenon of package forming,the reason is that with the increase of spinning speed,the amorphous orientation and the crystallization orientation are all increased,the internal stress of fiber also increases,the shrinkage which produced by stress relaxation in the process of deposit predominated,the higher the spinning speed,the shrinkage is more obvious.