How Does Plastic Degenerate?

General wisdom states that, in fact, plastic does not degenerate. Of course, we don’t know this for sure because some plastic items, such as plastic bags, might take 500 years or more to break down if they are buried in a landfill. If these items are lying in the open air, studies show they may decompose in a couple of decades.

The process of decomposition known as biodegredation involves tiny living organisms that take food material in and digest it. This is the unseen process that makes it possible to “get rid of” food items and other natural material. But these microorganisms don’t consider plastic bags made of polyethylene as food.

The plastic in bags and some other items might break down over time due to strong sunlight (photodegredation). But when buried in a landfill, this process obviously cannot work. Basically, this process involves the ultraviolet radiation and heat from the sun, which cause the item to break up but not truly degrade.

There are two things to consider with the material used in plastic bags, plastic containers and other items. First of all, millions of these items are discarded each day around the globe. Second and just as important however is that, since they don’t disintegrate easily, bags, containers and plastic products tend to clutter and clog wherever they end up.

In recent years, some companies have started to use a hybrid plastic in bags and other products, which allows the larger item to break down into smaller pieces. But even when the pieces are small enough to look like dust, they may stay around for hundreds of years.

The solution some companies have come up with for plastic that does not break down completely is to burn it at temperatures approaching 1000 degrees on the Celsius scale. Burning the items at lower temperatures is known to create fumes that are health hazards.

University studies have used one particular strain of bacteria, in controlled experiments, to break down plastics that are considered biodegradable. The process required a very exact temperature and careful measurement to get the correct amount of bacteria for the amount of plastic material used. One group of researchers was able to show visible reduction of the amount of plastic material, but the process has not been moved to a larger, commercial scale.

Another interesting study took place in India. There, a research team put plastic items and polyurethane into the soil where mangrove trees are the dominant plant. After a period of months, the researchers found that a specific type of microbe in that soil was capable of breaking down the items. The science behind this study is gradually finding its way into the commercial sector.

So, the general knowledge may be that plastic does not degrade or degenerate. But with increasing knowledge and new technology, this statement is not entirely true any longer. A material known as Bakelite dates back more than 100 years and is considered the first plastic manufactured. Items made from this material show no real signs of breaking down under normal use. For other plastics, science is making progress.

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