Polyethylene resin is a kind of thermoplastic general-purpose resin with multiple structures and characteristics, multiple varieties and brands, and is one of the three general-purpose materials. It mainly includes high-pressure low-density polyethylene (LDPE), low-pressure high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE) and various homopolymers or copolymers with ethylene as the main monomer.

High-pressure low-density polyethylene (LDPE) is a -(CH2-CH2-)-based thermoplastic. LDPE is a thermoplastic that is rigid, but not hard or brittle, and has a slightly waxy feel.The density of this type of resin is 0.910 ~ 0.935g/cm³.LDPE is characterized by the presence of many short branched chains, with 15-30 short branched chains in 1000 carbon atoms. Due to the irregular linear structure of LDPE, the symmetry is reduced, thus reducing the chain’s convergence ability.These structures result in a decrease in density and a corresponding decrease in crystallinity. A typical LDPE’ s crystallinity is about 50%, and the molecular weight of LDPE is about 10×104 to 50×104. Because it is non-toxic, it can be used as packaging materials for medical devices, medicines, food, toys and crops.

Non-toxic, low softening point, good thermal weldability, molding processability, good flexibility, impact resistance, and low temperature resistance; can work between -60 and -80 ℃, and has excellent electrical insulation (especially High frequency insulation).

LDPE has poor mechanical strength, poor heat resistance, poor environmental stress crack resistance,adhesiveness, adhesion, and printability. Also, it has very low water absorption (almost no water absorption). LDPE has excellent chemical stability, such as relatively stable to acids, alkalis, salts, and organic solvents, but has poor permeability to water vapor and air. LDPE is easy to burn and has a paraffin-like smell when burning. It is prone to degradation and discoloration under the action of light and heat, from white to yellow to brown, and finally to black, with reduced performance or cracks. Adding a certain amount of antioxidants and UV absorbers can improve performance. LDPE is cross-linked under chemical cross-linking agent or high-energy radiation to improve softening point, temperature resistance, stiffness, solvent resistance, etc. LDPE is suitable for various molding processes of thermoplastic molding and has good molding processability, such as injection molding, extrusion molding, blow molding, rotational molding, coating foam, thermoforming, hot air welding, thermal welding, etc.