What's The Difference Between LDPE, LLDPE, MDPE And HDPE Sheeting?

Polyethylene is a polyolefin. Polyolefins are high molecular weight hydrocarbons. Polyolefins include linear low-density polyethylene, low-density polyethylene, high-density polyethylene, polypropylene copolymer, polypropylene, and polymethyl pentene. These are the only plastics that have a lower specific gravity than water. This means that they weigh less than water. These materials can become brittle from oxidation and are damaged by exposure to UV light.

When ethylene is polymerized, the result is relatively straight polymer chains. From the main chain, they can branch out. We get different kinds of Polyethylenes from the varying degrees of branching in their molecular structure. Below are brief descriptions of how the polyethylenes differ from each other.

LDPE (Low-Density Polyethylene) has the most excessive branching. This causes the low density to have a less compact molecular structure, which makes it less dense. It has a density of 0.91-0.925g/cm³.

LLDPE (Linear Low-Density Polyethylene) has a significant number of short branches. Because it has shorter and more branches, its chains can slide against each other upon elongation without becoming entangled, like LPDE, which has long branching chains that would get caught on each other. This gives LLDPE higher tensile strength and impact and puncture resistance than the LDPE. It has a density of 0.91-0.94g/cm³.

MDPE (Medium Density Polyethylene) has a little less branching than the HDPE. It is less notch-sensitive than HDPE and has better stress-cracking resistance. It has a density range of 0.926 - 0.94 g/cm³

HDPE (High-Density Polyethylene) has minimal branching of its polymer chains. Because it is denser more rigid, and less porous than the LDPE. It has a density of 0.941-0.965g/cm³.