The research on polyester began in the 1930s, invented by British scientists such as Whinfield and Dickson. It was industrialized in the UK in 1949 and in the US in 1953. As one of the later-developed synthetic fiber products, polyester has grown rapidly in production.
The molecular weight of polyester ranges from 18,000 to 25,000, with a polymerization degree of 100 to 140. The macromolecules possess a symmetrical chemical structure and tend to crystallize under suitable conditions, resulting in a tightly packed fiber structure. The polyester macromolecules contain benzene rings, making them essentially rigid, while also incorporating aliphatic hydrocarbon chains, which provide a degree of flexibility. Apart from two terminal hydroxyl groups, no other polar groups are present in the macromolecules. The high ester content leads to hydrolysis and thermal cracking at elevated temperatures. Polyester is produced via melt spinning, with a circular cross-section and a glass-like rod shape along the longitudinal axis, appearing dry, straight, and smooth. Its density ranges from 1.38 to 1.40 g/cm³.
PPT fiber is the abbreviation for polypropylene terephthalate fiber. Some people abroad refer to PPT as the large-scale fiber of the 21st century, and its trade name is "Corterra".
PPT, PET, and PBT belong to the polyester family and have similar properties. PPT fiber combines the characteristics of polyester and nylon. Like polyester, it is easy to wash and dry, has good elasticity recovery and wrinkle resistance, as well as good stain resistance, anti light resistance, and hand feel. It has better dyeing performance than polyester and can be dyed under normal pressure. Under the same conditions, the dye has a higher penetration force on PPT fibers than PET, and the dyeing is uniform with good color fastness. Compared with nylon, PPT fiber has better wear resistance and tensile recovery, as well as greater elasticity and fluffiness, making it more suitable for making materials such as carpets.
PBT fiber is the abbreviation for polybutylene terephthalate fiber. PBT fiber is made by the condensation of dimethyl terephthalate (DMT) or terephthalic acid (TPA), the main raw material of polyester, with 1,4-butanediol. DMT and 1,4-butanediol were subjected to condensation reaction at high temperature and vacuum degree, using organic titanium or tin compounds and tetrabutyl titanate as catalysts, and then melt spun to produce PBT fibers. The polymerization, spinning, and post-processing processes and equipment of PBT fibers are basically the same as those of polyester fibers.
PBT fiber has the same characteristics as polyester, such as good strength, easy washing and quick drying, stable size, and good shape retention. The most important thing is that the flexible part of its macromolecular chain is relatively long, so it breaks and elongates, has good elasticity, and does not change much after heating, with a soft touch. Another advantage of PBT fiber is that it has better dyeing properties than polyester. Satisfactory dyeing results can be obtained by dyeing PBT fabrics with dispersed dyes under atmospheric boiling conditions. In addition, PBT fiber has good aging resistance, chemical resistance and heat resistance. PBT fiber has a wide range of applications in engineering plastics, household appliance casings, and machine parts.
PEN fiber is the abbreviation for polyethylene naphthalate fiber. Like polyester, PEN fiber is a semi crystalline thermoplastic polyester material initially introduced by KASA in the United States. Its production process involves ester exchange between dimethyl 2,6-naphthalate (NDC) and ethylene glycol (EG), followed by condensation to obtain PEN fiber; Another method is to directly esterify 2,6-naphthalenedicarboxylic acid (NDCA) with ethylene glycol (EG), and then produce it through condensation. If a small amount of compounds containing organic amines and organic phosphorus are added, the thermal stability of PEN can be improved.
The spinning process of PEN fiber is similar to that of polyester, and its process flow is: slice drying → high-speed spinning → stretching. Due to the higher glass transition temperature of PEN fiber compared to polyester, the drawing process needs to be adjusted accordingly. Multiple drawing passes should be used and the drawing temperature should be increased to avoid affecting the quality of the fiber due to slow molecular orientation speed. Compared with conventional polyester, PEN fiber has better mechanical and thermal properties, such as high strength, high modulus, good tensile resistance, and high rigidity; Good heat resistance, stable size, not easily deformed, and good flame retardancy; Good chemical resistance and hydrolysis resistance; UV resistant and aging resistant.