Polypropylene ethylene has many excellent properties that other general synthetic rubbers do not have. In addition, the monomer is cheap and easy to obtain and has a wide range of uses. It is the fastest developing one of the seven major synthetic rubber varieties abroad since the 1980s. Its output, production capacity and consumption rank third in developed countries, second only to styrene butadiene rubber and CIS butadiene rubber. In 1998, the total production capacity of EPR in the world was about 1.02 million tons and the consumption was 814000 tons. According to preliminary statistics, the consumption in 1999 was about 836100 tons, and it is expected to reach 98000 tons in 2003. From 1998 to 2003, the demand growth rate of EPR was 3.8%, which was higher than that of styrene butadiene rubber and CIS polybutadiene rubber.

Dihydroxyethyl terephthalate was synthesized by transesterification of dimethyl terephthalate with ethylene glycol or esterification of purified terephthalic acid with ethylene glycol, and then polycondensation. Pet is divided into fiber grade polyester chips and non fiber grade polyester chips. ① Fiber grade polyester is used to manufacture polyester staple fiber and polyester filament. It is the raw material for polyester fiber enterprises to process fiber and related products. ② Non fiber grade polyester is also used for bottles, films and other purposes. It is widely used in packaging industry, electronic appliances, medical and health care, construction, automobile and other fields. Packaging is not only the largest non fiber application market of polyester, but also the fastest growing field of pet. Dihydroxyethyl terephthalate was synthesized by transesterification of dimethyl terephthalate with ethylene glycol or esterification of purified terephthalic acid with ethylene glyc

The intrinsic viscosity of general fiber grade polyester chips is 0.645. The intrinsic viscosity mentioned here is used to characterize the molecular weight of polyester in industry. Measuring the intrinsic viscosity can not only correctly evaluate the quality of polyester, but also provide an important basis for formulating spinning process conditions. When the intrinsic viscosity of polyester chip is too low, the molecular weight of polyester is small, the spinning process is difficult to stretch, or even has no spinnability, and it is easy to break. However, if the viscosity is too high, the tensile stress during drawing is too large, and the macromolecules are not well oriented, the intrinsic viscosity has an impact on the spinning operation stability, filament evenness and dyeing evenness. Therefore, ensuring the stability of the intrinsic viscosity is of great help to improve the spinning quality.