Views:4 Author:Site Editor Publish Time: 2021-07-19 Origin:Site
EVA is an amorphous plastic, non-toxic, with a specific gravity of 0.95g/cm3 (lighter than water). Its products have poor surface gloss, good elasticity, softness and light weight, low mechanical strength, good fluidity, and easy processing and molding. The shrinkage rate is relatively large (2%), and EVA can be used as a carrier for color master batches.
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, adhesion, tensile processing, transparency and gloss. , At the same time, it has rubber-like elasticity, excellent ozone resistance, non-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 increases, and its elasticity, flexibility, cohesiveness, compatibility, transparency, and solubility are improved; as the VA content decreases, its performance is close to polyethylene, that is, the rigidity becomes larger. Increased wear resistance and electrical insulation. When the VA content is constant, the melt index increases, the softening point decreases, the processability and surface gloss are improved, but the strength decreases; on the contrary, the melt index decreases, the relative molecular weight increases, and the impact resistance and stress resistance are increased. Improved cracking.
The heat resistance and oil resistance of EVA are slightly worse.
EVA can use LDPE molding methods and processing equipment, and the processing temperature is 20-30°C lower than LDPE.
The main molding methods are: injection molding, blow molding, extrusion, calendering and coating, extrusion coating, multi-layer co-extrusion blow molding compounding, foam molding, vacuum molding, secondary processing and other methods.
Main processing conditions: the temperature of extruded film is 140～180℃, and the temperature of injection moulding is 200～250℃.
EVA has a wide range of uses, which can be used to manufacture films, composite films, various molded products, foamed products, adhesives, etc.