Polyethylene sheets are lightweight plastics that are corrosion resistant to chemicals and have low moisture absorption. They are required to meet the specifications of Federal Supply Class (FSC): 9330 - Plastics Fabricated Materials - Plastic Sheet. Most plastic sheets can easily be cut with a scissors and are easily bent and folded.
Sheet plastics have been designed to have low thermal conductivity and low coefficient of expansion. This means they serve as good thermal insulators and do not expand appreciably when temperatures change.Their thermal properties make them excellent insulators in the housing industry and in green houses where plants are nurtured.
Polyethylene is one of the best known insulating materials used in electrical cable insulation. It has a high dielectric constant, a property that makes it useful in high-voltage signal transmission of power. Also its high dielectric constant allows thinner insulation walls for cables and a replacement for thicker conventional rubber insulation. In particular, shielded SDN control cables use polyethylene insulation.
Polyethylene (PE) exists in two basic types that influence its optical properties: high-density polyethylene (HDPE) and low-density polyethylene (LDPE). HDPE has higher molecular weight and PE molecules are densely packed. LDPE has better crystalline structure but less molecular weight. The density and crystal structure influence the optical properties of haze, transparency and gloss. For example, HDPE shows more haze, is less transparent but more glossy than LPDE.