Polyethylene is a polyolefin, which are high molecular weight hydrocarbons that include high–density polyethylene, low-densitypolyethylene, polypropylene copolymer, polymethyl pentene and polypropylene. These represent the only plastics with a lower specific gravity than water, or in other words, they are the only plastics that weigh less than water. While some forms of these materials are sensitive to oxidization and UV light, LLDPE is resistant to both of these things as well as other natural environmental strains.
Ethylene is polymerized in order to create a fairly straight polymer chain. These chains branch out in unique ways from the main chain depending upon the varying degree of branching in their molecular structure.
LDPE (Low Density Polyethylene): LDPE has the most extensive branching compared to other polyolefins. As a result, it is lowdensity and has a less compact molecular structure. It has a density of 0.910-0.925 g/cm3.
LLDPE (Linear Low Density Polyethylene): LLDPE is known for its vast number of short branches. While its branches are shorter, there are more of them and they are able to move against one another upon elongation without entangling together. On the other hand, LDPE’s longer branches easily tangle up with one another. That’s why LLDPE is much stronger and able to withstand greater impact and puncture damage. It has a density of 0.91-0.94 g/cm3.
HDPE (High Density Polyethylene): HDPE’s polymer chains include less branching. As a result, it is a denser material that is more ridged and less permeable than LDPE. HDPE is a clean product to produce as it creates no harmful emissions and leaks no toxic chemicals into soil or water. HDPE is among the most commonly used plastic in the US. It has a density of 0.941-0.965 g/cm3.