[Chemical Knowledge]：Properties, uses, upstream and downstream raw materials, storage methods of polyethylene terephthalate, trade name of polyethylene terephthalate

Properties of polyethylene terephthalate

polyethylene terephthalate (PET), a thermoplastic polymer, has excellent physical and chemical properties. The molecular structure of PET consists of terephthalic acid and ethylene glycol, which gives it a high degree of crystallinity and good mechanical strength. PET has a relatively high melting point of about 250°C and a glass transition temperature of about 70-80°C. It has good chemical resistance, tensile strength and wear resistance at room temperature. The transparency and gloss of PET also make it particularly important in certain applications.

Uses of polyethylene terephthalate

PET has been widely used in many fields because of its unique properties. Its main uses include:

1. packaging Materials the most common application of PET is in the manufacture of beverage bottles, especially carbonated beverage bottles. Its high strength and low weight characteristics make it an ideal packaging material. In addition, PET is also used to make food packaging boxes and pharmaceutical packaging.
2. fiber in the textile industry, PET is called polyester, which is widely used in the production of various fiber products, such as clothing, carpets and industrial fibers.
3. engineering plastics PET's high strength and good thermal stability make it suitable for manufacturing mechanical parts, electronic components and auto parts.
4. Film and Sheet: PET film is widely used in electrical insulation materials, magnetic tapes and packaging films due to its excellent transparency and electrical insulation properties.

Upstream raw materials for polyethylene terephthalate

the production of PET mainly depends on two key raw materials: terephthalic acid (PTA) and ethylene glycol (EG).

1. Terephthalic acid (PTA): PTA is one of the main raw materials of PET, which is oxidized by p-xylene (PX) obtained in the petrochemical production process. PX generates PTA through catalytic oxidation reaction, and the purity reaches a certain standard before it can be used in the production of PET.
2. Ethylene Glycol (EG): EG is another important raw material, usually made from ethylene by oxidation reaction. EG is used as a comonomer in the production of PET and reacts with PTA to produce PET.

Downstream Products of Polyethylene Terephthalate

the wide application of PET has led to a wide range of downstream products, including:

1. preforms and beverage bottles: This is the most important application field of PET, and the preforms produced can be further blown into various beverage bottles.
2. fiber products PET fiber is widely used in the manufacture of various textiles, such as polyester fiber, non-woven fabric and rope.
3. engineering plastic products: Used in the manufacture of auto parts, electrical components and mechanical parts.
4. Film and Sheet: Used as insulating materials in packaging, optical materials and electronic equipment.

Storage method of polyethylene terephthalate

in order to ensure the quality and performance of PET, a reasonable storage method is particularly important. The following are storage recommendations for PET:

1. environmental Control: PET should be stored in a dry, cool, well-ventilated environment, avoid direct sunlight and high temperature to prevent thermal oxidation and degradation.
2. Humidity Management: PET is sensitive to moisture and will affect its processing performance after moisture absorption. Therefore, the PET particles should be dried before use, usually at a temperature of 120-160°C for 4-6 hours.
3. Avoid pollution: Avoid contact with other chemical substances during storage to prevent pollution and chemical reactions from affecting the purity and performance of PET.
4. Packaging protection PET pellets are usually stored in sealed bags to prevent moisture absorption and contamination. During transportation, attention should also be paid to moisture-proof and anti-collision to ensure the integrity of PET particles.

Environment and Sustainable Development

with the increasing awareness of environmental protection and the need for sustainable development, the recycling of PET is becoming more and more important. PET has excellent recycling performance and can be reused through mechanical recycling and chemical recycling.

1. Mechanical recovery waste PET bottles and fibers are cleaned, crushed and reprocessed to produce recycled PET pellets that can be used to make new preforms, fibers and other products.
2. Chemical recovery PET is depolymerized to its monomers or oligomers, and new PET is produced by purification and repolymerization. This method can effectively remove impurities and improve the quality of recycled PET.

Through effective recycling, PET can not only reduce environmental pollution, but also save resources and achieve sustainable development goals.

Conclusion

as a thermoplastic polymer with excellent properties, polyethylene terephthalate (PET) plays an important role in modern industry and daily life. From its chemical properties, wide range of uses to the detailed analysis of upstream and downstream raw materials and storage methods, we can see the wide application prospects of PET in various fields. Through scientific recycling, PET can not only meet the needs of industry, but also achieve the goal of environmental protection and sustainable development.