Polyethylene film is a resinous material with thermoplastic properties that is synthesized by inducing oxidative polymerization of ethylene gas. The degree of pressure used in its manufacturing varies according to the density and melting point of the virgin polymer resin being used. Most commonly, sheets of polyethylene film are produced using a process known as blown film extrusion, in which the polymer resin is melted to its flow point and then extruded through a die to produce a tube of plastic. While the polyethylene is still supple, the tube is closed off at one end and then blown to inflate and stretch the film into the desired length and thickness. The thickness of polyethylene film can be as thin as .0004 inch (10.16 microns).
The introduction of this film was considered groundbreaking in terms of its application in the packaging industry. Specifically, it has proven to be highly valuable in the flexible packaging market. In fact, it has captured the majority of the plastic packaging segment, which primarily consists of bags and wrapping material used for storage or to provide protection from the environment. This includes plastic wrap to protect agricultural crops, as well as ordinary kitchen wrap used to preserve food. Of course, polyethylene film is also essential in the manufacturing of bags, from dry cleaning protective covers to garbage and grocery bags.
One reason that polyethylene film dominates all other materials formerly used in packaging is its ability to self-seal under controlled heat. Shrink wrap, for example, protects items by literally shrinking around them to form a seal in response to the application of heat. This ability makes this film ideal for use in making tamper resistant packaging as well as to seal electrical wiring. In addition, polyethylene sheets can be sewn or stapled together, or even bonded with glue.
Polyethylene film is also used extensively in the agricultural industry where it has many applications. For one thing, it is used to protect crops and seeds from pests and disease. This material also helps to prevent the escape of moisture and heat.
While most people are familiar with polyethylene film due to its presence in many consumer products, it has a few lesser-known applications. In fact, it is frequently used in building and construction. Aside from acting as a tarpaulin to protect equipment and building materials, it is also placed in the structural interior of buildings to prevent the invasion of moisture. Polyethylene film also serves as a blanket to promote the curing of concrete slabs.
