Differences between three kinds of PE plastic
Polyethylene, short for PE, is commonly used in three categories: LDPE HDPE LLDPE. The monomers of the three kinds of polyethylene are the same, but the process conditions used to synthesize these polyethylenes are different. The properties of the three kinds of materials are quite different.LDPE, short for low density polyethylene, scientific name of low density polyethylene high pressure polyethylene. Polyethylene is a translucent white wax material with light density, softness and toughness, slightly elongated, non-toxic, odorless combustion characteristics and flammability. It can continue to burn after fire. The flame is yellow at the top and blue at the bottom. When burning, it will melt, with liquid dropping, no black smoke coming out, and emit the odor of burning paraffin.
Disadvantages: poor mechanical properties, poor air permeability, easy deformation, easy aging, brittle, easy stress cracking, low surface hardness, easy scratch, difficult printing, electroplating, dull surface.
Uses: for extrusion packaging film, composite film, and hose; for injection molding of low-grade commodities and shells; for extrusion blow-moulding containers.
HDPE, short for high density polyethylene, its scientific name is high density polyethylene low pressure polyethylene. HDPE is an opaque white wax-like material with light specific gravity, softness and toughness, but slightly harder and elongated than LDPE. Non-toxic, tasteless, flammable combustion characteristics, after fire can continue to burn, the flame is yellow at the top, blue at the bottom. When burning, it will melt, with liquid dropping, no black smoke coming out, and emit the odor of burning paraffin.
Advantages: acid and alkali resistance, organic solvent resistance, excellent electrical insulation, low temperature can still maintain a certain degree of toughness, surface hardness, tensile strength rigidity and other mechanical strength are higher than LDPE and close to PP, tougher than PP, but the surface finish is not as good as PP.Disadvantages: poor mechanical properties, poor air permeability, easy deformation, easy aging, easy brittleness, brittleness lower than PP, easy stress cracking, low surface hardness, easy scratch, difficult printing, non-plating, dull surface.
Uses: Used for extruding packaging film, rope, woven bag, fishing net, water pipe; used for injection moulding of low-grade commodities and shells, non-load-bearing components, rubber box, turnover box; used for extruding blow-moulding containers and bottles of hollow products.
Advantages: acid and alkali resistance, organic solvent resistance, excellent electrical insulation, low temperature can still maintain a certain degree of toughness, surface hardness, tensile strength, rigidity and other mechanical strength are higher than LDPE, but lower than HDPE, LLDPE puncture resistance is the best. Tear resistance, especially suitable for the production of thin film, but high strength than LDPE.
Disadvantages: poor mechanical properties, poor air permeability, easy deformation, easy aging, easy brittleness, brittleness lower than PP. Easy stress cracking, low surface hardness, easy scratch, difficult printing. Can not be electroplated, the surface is glossy.
Uses: Used for extruding packaging film, tape, cable, film produced, also known as paper-like film; used for injection molding of low-grade commodities and shells; used for extruding blow-moulding containers, hollow product bottles.
The difference between LDPE, HDPE and LLDPE is mainly in density, which leads to the difference in mechanical properties. One is rigid and the other is flexible. The difference between LLDPE and LDPE is mainly in molecular structure. LLDPE has more branched chains. Therefore, this material is flexible and rigid.
