CHEMICAL PROPERTIES OF ETHYLENE-VINYL ACETATE COPOLYMERS

CHEMICAL CHARACTERISTICS OF ETHYLENE-VINYL ACETATE COPOLYMER

ethylene-vinyl acetate copolymer (EVA) is a widely used polymer material with excellent physical and chemical properties. It is a product obtained by copolymerization of ethylene (Ethylene) and vinyl acetate (Vinyl Acetate) at a certain ratio. The unique properties of EVA make it widely used in many industries, such as packaging, footwear, medical and automotive. In this paper, the chemical characteristics of ethylene-vinyl acetate copolymer will be discussed in detail, and its structural characteristics, chemical resistance, thermal stability and plasticity will be analyzed.

1. Ethylene-vinyl acetate copolymer structure characteristics

The chemical characteristics of ethylene-vinyl acetate copolymer are closely related to its molecular structure. EVA is an alternating copolymer formed by copolymerizing ethylene and vinyl acetate monomers under certain conditions, wherein the vinyl acetate content is usually between 10% and 40%. The introduction of vinyl acetate changed the structure of ethylene, making the molecular chain of EVA more flexible. The polar group (ester group) of the vinyl acetate unit can interact with water, polar solvents and the like to impart excellent adhesiveness, transparency and low-temperature performance to EVA.

2. Ethylene-vinyl acetate copolymer chemical resistance

The chemical resistance of ethylene-vinyl acetate copolymers makes them outstanding in many applications. EVA has good acid resistance, alkali resistance and water resistance. Especially when the content of vinyl acetate is higher, EVA can better resist the attack of polar solvent. The ester group in the vinyl acetate molecule can interact with some chemicals, which provides advantages for EVA in some special applications, such as anti-corrosion coatings and packaging films. EVA has poor resistance to strong oxidants. Too strong oxidizing environment may cause its molecular chain to break, so you need to pay attention when choosing the use environment.

3. Ethylene-vinyl acetate copolymer thermal stability

Under high temperature environment, the thermal stability of ethylene-vinyl acetate copolymer is one of the key factors affecting its application performance. The thermal stability of EVA is closely related to the structure of its molecular chain and the content of vinyl acetate. The ester group of vinyl acetate can improve the flexibility of EVA at low temperature, but the high content of vinyl acetate may reduce its high temperature stability. At higher temperatures, EVA may undergo thermal aging, which is manifested by degradation of physical properties. Therefore, in high temperature applications, EVA needs to pay special attention to temperature control to avoid its performance degradation.

4. Ethylene-vinyl acetate copolymer plasticity and processing properties

Ethylene-vinyl acetate copolymer has excellent plasticity and processability, which makes it have high production efficiency in the production process. Because its molecular chain is relatively soft, EVA can be easily shaped during processing. The processing temperature of EVA is generally between 160°C and 220°C, which can meet the common thermoplastic processing requirements, such as extrusion and injection molding. EVA has good low-temperature plasticity, so it is widely used in low-temperature environments, such as frozen food packaging, automobile sealing strips, etc. The addition of vinyl acetate also enhances its adhesion to other materials, further expanding its application in composite materials.

5. Ethylene-vinyl acetate copolymer applications

Due to its excellent chemical properties, ethylene-vinyl acetate copolymer is widely used in many fields. In the packaging industry, EVA is often used as a heat sealing material, and its good transparency and adhesion make it an ideal packaging film material. EVA is also widely used in the field of shoe materials, especially in sneaker, insoles and other products, to provide a comfortable wearing experience. In the automotive industry, EVA is used in the manufacture of interior materials, sealing strips, etc., with good anti-aging properties. Because of its flexibility and transparency, EVA is also widely used in the medical field, such as infusion tubes, pharmaceutical packaging and so on.

Conclusion

Because of its unique chemical properties, ethylene-vinyl acetate copolymer has become a very important class of polymer materials in modern industry. Its molecular structure, chemical resistance, thermal stability and plasticity make EVA widely used in packaging, shoe materials, automotive and medical fields. In practical applications, adjusting the content of vinyl acetate according to specific requirements can further optimize its performance to meet the needs of different fields.