Views: 19 Author: Site Editor Publish Time: 2018-08-17 Origin: Site
EVA is an amorphous plastic, non-toxic, with a specific gravity of 0.95g/cm3 (lighter than water). EVA products have poor surface gloss, good elasticity, softness, light weight, low mechanical strength, good fluidity and easy processing. The shrinkage is large (2%) and EVA can be used as a carrier for color concentrates.
EVA is a random copolymer of ethylene and vinyl acetate. It is characterized by good flexibility, toughness, low temperature resistance (flexibility at 58 ° C), weather resistance, stress crack resistance, heat sealability, cohesiveness, processability, transparency and gloss. At the same time, it has rubber-like elasticity, excellent ozone resistance, no toxicity, good processing and dyeing properties, and good blending with fillers. The VA content in EVA is different, and the relative molecular mass of EVA is different, and the performance is different. When the melt index is constant, the VA content is increased, and its elasticity, flexibility, adhesion, compatibility, transparency, and solubility are improved. As the VA content is lowered, its performance is close to that of polyethylene, that is, the rigidity becomes large. Wear resistance and electrical insulation increase. When the VA content is constant, the melt index increases, the softening point decreases, the workability and surface gloss are improved, but the strength is lowered. Conversely, when the melt index becomes smaller, the relative molecular mass is increased, impact resistance and stress resistance. Increased cracking.
EVA has a slightly poor heat resistance and oil resistance.
EVA can adopt LDPE molding method and processing equipment, and the processing temperature is 20~30 °C lower than LDPE.
The main molding methods include: injection molding, blow molding, extrusion, calendering, extrusion coating, multi-layer co-extrusion blow molding, foam molding, vacuum forming, secondary processing and the like.
The main processing conditions: extrusion film temperature is 140 ~ 180 ° C, injection molding temperature 200 ~ 250 ° C.
EVA is widely used to manufacture films, composite films, various molded products, foamed products, adhesives, etc.