Dty, fdy, and poy refer to three different processes for processing chemical fiber filaments. poy is a pre-oriented filament that undergoes initial stretching orientation; DTY is a product made of poy fibers after false twisting and stretching, with a certain degree of twist and elasticity, and can be used for weaving and knitting.
FDY is a fully drawn yarn with a spinning speed of 4000-5500m/min. The fibers are fully drawn and oriented, with high strength. It is commonly used in water jet and air jet loom, warp knitting machines, and circular machines.
Polyester is an important variety of synthetic fibers and is the trade name for polyester fibers in China. It is a fiber-forming polymer, polyethylene terephthalate (PET), which is made from purified terephthalic acid (PTA) or dimethyl terephthalate (DMT) and ethylene glycol (EG) through esterification or transesterification and polycondensation and is spun and post-treated.
physical property
① Color. Polyester is generally milky white with mercerization. To produce matte products, a matting agent TiO2 needs to be added before spinning. To produce pure white products, a whitening agent needs to be added. To produce colored silk, pigments or dyes need to be added to the spinning melt.
② Surface and cross-sectional shape. Conventional polyester has a smooth surface and a nearly circular cross-section. If profiled spinneret is used, fibers with special cross sections can be made, such as triangular, Y-shaped, hollow, and other profiled cross sections.
③ Density. When polyester is completely amorphous, its density is 1.333g/cm3. When fully crystallized, it is 1.455g/cm3. Usually, polyester has high crystallinity, with a density of 1.38-1.40g/cm3, which is similar to wool (1.32g/cm3).
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