Polyethylene Resin: What is it?

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Polyethylene resin is a type of thermoplastic commonly used in the manufacture of things like plastic shopping bags, packaging, some pipes and machine parts, and even a number of toys. It is a flexible chemical composite, relatively cheap to produce and widely accessible. The “resin” part of the name is mostly in reference to the viscosity of the substance. It is made up of complex chains of ethylene monomers, which are small molecules that combine in repeating patterns to form larger compounds known as polymers. Manufacturers and researchers typically heat polymers to activate and manipulate them, although at room temperature most are solid and will almost always hold their shape. Some are found in nature, but most of those used in commercial applications are the result of synthetic manufacturing. There are many variations and most of them can be recycled. However, not all communities have recycling programs, and in most places, plastic ends up in landfills and the environment anyway. Plastics in the polyethylene family do not biodegrade, and a number of environmental activists have expressed concern about the continued production of products using these materials.

Understand resins in general

A resin, at least in science, is usually a thick liquid composed of complex polymers. Tree sap is a common natural example. Some polyethylenes naturally occur this way, typically as a byproduct of petroleum burning or pooling and evaporation. More commonly, though, it is created synthetically in a laboratory. Resins can be cast into molds or combined with other materials to fix their shape, then heated or cooled to form a solid.

At room temperature they tend to be very stable and for this reason they are often used for food and drink. Most consumers never see plastic in its resin form. Perhaps for this reason in most cases it is simply called “polyethylene”.

From a chemical perspective
Ethylene is a hydrocarbon with the chemical formula C2H4. Polyethylene resin has a formula of C2nH4n+2, where “n” is the number of monomers that have combined through the polymerization process to form this chain. The polymerization process transforms ethylene into a thermoplastic resin.

Primary types

There are two types of resin, natural and synthetic. Natural resin is a hydrocarbon secreted by plants and other natural processes in the earth. As the name indicates, synthetic resin is produced through a process called esterification. It is a chemical process involving an alcohol and an acid, which form a hydroxyl compound called an ester. Both natural and synthetic resins are high viscosity materials capable of hardening at a certain temperature.

variations
This type of resin has a number of variants, with names such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), very low-density polyethylene (VLDPE), and so on, based on density and crystallinity. Due to these different compositions, this resin has numerous uses in the home and in various industries. During the manufacturing process, the resin is injected into machines with specific pressure and temperature settings. The hardening property of the resin helps fix the raw material as required.
Recycling and environmental problems
PE, short for polyethylene, is normally marked to indicate that plastic packaging or a plastic product has been made with a resin. It also has the three arrow marks to indicate it can be recycled. However, most of the polyethylene products manufactured around the world end up in the ocean or in landfills. With over 60 million tons of material produced worldwide each year, the use of polyethylene resin has become a serious environmental issue.

Studies are underway in many parts of the world to produce biodegradable polyethylene resin to overcome the environmental problem. In terms of the use of polyethylene, recent medical research has indicated the possibility of using HDPE to create implants for facial deformities. Cross-linking of ultra-high molecular weight polyethylene (UHMWPE) is also being evaluated to improve the wear problem of current total joint replacement devices.

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