Polyethylene HDPE

Polyethylene HDPE

What is Polyethylene?

Polyethylene is a thermoplastic material produced by polymerizing ethylene gas with a catalyst in a reactor. Polyethylenes are characterized by their low cost, light weight, and excellent low temperature properties. Also, Polyethylenes exhibit excellent resistance to gamma rays in atomic radiation and is nontoxic. Toughness, near-zero moisture absorption, excellent chemical resistance, excellent electrical insulating properties, low coefficient of friction, and ease of processing add to its impressive list of benefits.

Based on their specific gravity, Polyethylene is divided into two main categories: Low density (.910 – .925), and High Density (.941 – .965).

Low Density, LDPE, was the first developed and is still dominant in terms of volume and sales. LDPE is flexible, and has high impact strength but relatively low heat resistance (160 degrees to 180 degrees F). Dielectric properties at room temperature are considered excellent. Resistance to attack by acids and inorganic chemicals at room temperature dictates the reason why no suitable solvent cements have been developed for this material. Above 66 degrees C (115 degrees F), polyethylene will dissolve in a number of common solvents. The lack of rigidity and a relatively soft surface precludes the use of this material in structural applications. Specification: L-P-390 CL.L

High Density, HDPE, is produced by packing molecules more closely together. HDPE has greater stiffness, rigidity, heat resistance, and increased resistance to permeability than LDPE. HDPEs are classified as either homopolymers which are stiffer, and copolymers which are more stress-crack resistant. HDPE is used for structural applications as it is almost four times better in tensile strength, and three times better in compressive strength than LDPE. HDPE has a working temperature of 212 degrees F – 220 degrees F under low load conditions and it may be autoclaved at sterilizable temperatures.