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What is the difference between various types of high pressure polyethylene

Time : 2022-07-15 Hits : 36

LDPE is the abbreviation of high pressure polyethylene, namely low density polyethylene

The abbreviation of low pressure polyethylene is HDPE, that is, high density polyethylene

The two have different densities. Generally, those with a density greater than 0.94 are HDPE, those with a density less than 0.925 are LDPE, and those in between are MDPE (medium density polyethylene).

LDPE (Chinese name: Low Density High Pressure Polyethylene): Sensory identification: soft to the touch: white and transparent, but average transparency, combustion identification: yellow on the burning flame and blue on the bottom; no smoke when burning, smell of paraffin, melting and dripping, easy to burn brushed

HDPE (High Density Polyethylene): HDPE is a highly crystalline, non-polar thermoplastic resin. The appearance of the original HDPE is milky white, and it is translucent to a certain extent in the thin section. PE has excellent resistance to most household and industrial chemicals. Certain types of chemicals are chemically aggressive, such as corrosive oxidants (concentrated nitric acid), aromatic hydrocarbons (xylene), and halogenated hydrocarbons (carbon tetrachloride). The polymer is non-hygroscopic and has good water vapour resistance for packaging applications. HDPE has good electrical properties, especially high insulation dielectric strength, making it very suitable for wires and cables. Medium to high molecular weight grades have excellent impact resistance at ambient temperatures and even as low as -40F

(1) Low density polyethylene (LDPE)

It is usually produced by high pressure method (147.17-196.2MPa), so it is also called high pressure polyethylene. Because the polyethylene molecular chain produced by the high pressure method contains more long and short branches (the average number of branches per 1000 carbon chain atoms is 21), the crystallinity is lower (45%-65%), and the density is higher. Small (0.910-0.925), light in weight, flexible, good in low temperature resistance and impact resistance. LDPE is widely used in the production of films, pipes (soft), cable insulation and sheathing, artificial leather, etc.

(2) High Density Polyethylene (HDPE)

It is mainly produced by low pressure, so it is also called low pressure polyethylene. HDPE molecules have few branches, high crystallinity (85%-90%), high density (0.941-0.965), high service temperature, good hardness, mechanical strength and chemical resistance. It is suitable for hollow blow molding, injection molding and extrusion of various products (hard), such as various containers, nets, packing tapes, and can be used as cable cladding, pipes, profiles, sheets, etc.