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What is Polyethylene Packaging?

A plastic bag made with polyethylene.
Polyethylene is a very strong plastic and can be found in bulletproof vests.
Polyethylene sheets are generally sold in rolls.
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  • Written By: Karyn Maier
  • Edited By: Bronwyn Harris
  • Last Modified Date: 13 August 2014
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Polyethylene packaging consists of various forms and grades of thermoplastic polyethylene sheets or film to wrap, seal, and protect consumer goods. Polyethylene, which is obtained from petroleum polymers, is the ideal medium with which to accomplish these tasks since the material is both durable and resistant to environmental hazards. In fact, polyethylene packaging is considered superior to any other material for this purpose and its use is widespread in the flexible packaging market.

What makes polyethylene packaging so reliable is its molecular structure. Its cellular makeup is so cross-linked that it is virtually impossible for water vapor to pass through. This also makes polyethylene packaging resistant to damage from coming into contact with chemicals or solvents, as well as being able to withstand friction. Of course, there are varying grades of polyethylene, ranging from very high density to low density and high molecular weight. Each type of polyethylene provides unique properties, such as elasticity, impermeability, clarity, or high tensile strength.

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Another benefit to using polyethylene packaging is that many grades can be heat-sealed using ultrasonic or high vapor heating methods. This simply means that the material can be wrapped around a product and then shrunk to snugly fit the dimensions of the item by applying heat. Since this forms a vacuum seal which moisture cannot permeate, polyethylene packaging is particularly desirable to wrap and protect computer and electronic components. It is also valuable in making plastic packaging tamper-proof. In addition, polyethylene sheets and film are available in varying density and thickness, and even in designer colors.

Polyethylene packaging is relatively inexpensive to produce. However, the method of ethane polymerization used will determine the properties and manufacturing cost of the final product. Most often, polymerization is achieved by the addition of a chemical catalyst, such as titanium. However, additional applications may be made during the process to obtain specific results. For instance, treatment with high voltage creates extended chain crystal polyethylene, which is transparent despite having a very high density.

While polyethylene offers certain advantages as a packaging material, it does have some characteristics that may be considered disadvantageous at times. For one thing, some grades of polyethylene tend to possess a high degree of thermal expansion. In fact, polymers generally expand about four times more in volume than metals. In addition, most grades of medium-density polyethylene lack sufficient stiffness to be used in some packaging applications. Finally, polyethylene packaging is not impervious to ultraviolet light, making its properties vulnerable to degradation when exposed to sunlight for extended periods.

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starrynight
Post 2

@Monika - Polyethylene packaging seems like a necessary evil, maybe just for now. However, I kind of feel like if there was some environmentally friendly alternative, we would have found it by now.

Being "green" has been a pretty big trend in marketing in the last decade or so. I'm sure some company would love to advertise they found a "green" alternative to polyethylene. So if no one has jumped on this, maybe there isn't a green alternative to polyethylene.

Monika
Post 1

Polyethylene packaging is great and all, but I really wish they would come out with a more environmentally friendly way to package consumer goods. I mean, I know there are a lot of positives to polyethylene packaging.

However, those positives don't cancel out the pollution problem. We create way too much trash every year packaging consumer goods in plastic that doesn't biodegrade. There has to be a better way.

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