Bioplastics and biodegradable plastics

From cars to food wrap and from planes to pens, you can make anything and everything from plastics—unquestionably the world’s most versatile materials. But there’s a snag. Plastics are synthetic (artificially created) chemicals that don’t belong in our world and don’t mix well with nature. Discarded plastics are a big cause of pollution, cluttering rivers, seas, and beaches, killing fish, choking birds, and making our environment a much less attractive place. Public pressure to clean up has produced plastics that seem to be more environmentally friendly. But are they all they’re cracked up to be?


The theory behind bioplastics is simple: if we could make plastics from kinder chemicals to start with, they’d break down more quickly and easily when we got rid of them. The most familiar bioplastics are made from natural materials such as corn starch, and sold under such names as EverCorn™ and NatureWorks. With a distinct emphasis on environmental credentials. Some bioplastics look virtually indistinguishable from traditional petrochemical plastics. Polylactide acid (PLA) looks and behaves like polyethylene and polypropylene and is now widely used for food containers.

According to NatureWorks, making PLA saves two thirds the energy you need to make traditional plastics. Unlike traditional plastics and biodegradable plastics, bioplastics generally do not produce a net increase in carbon dioxide gas when they break down. Because the plants that were used to make them absorbed the same amount of carbon dioxide to begin with. PLA, for example, produces almost 70 percent less greenhouse gases when it degrades in landfills.

Another good thing about bioplastics is that they’re generally compostable: they decay into natural materials that blend harmlessly with soil. Some bioplastics can break down in a matter of weeks. The cornstarch molecules they contain slowly absorb water and swell up, causing them to break apart into small fragments that bacteria can digest more readily.

Unfortunately, not all bioplastics compost easily or completely and some leave toxic residues or plastic fragments behind. Some will break down only at high temperatures in industrial-scale, municipal composters or digesters, or in biologically active landfills (also called bioreactor landfills). Not on ordinary home compost heaps or in conventional landfills. There are various eco-labeling standards around the world that spell out the difference between home and industrial composting. And the amount of time in which a plastic must degrade in order to qualify.

The global plastics problem

Plastics are carbon-based polymers (long-chain molecules that repeat their structures over and over) and we make them mostly from petroleum. They’re incredibly versatile—by definition: the word plastic, which means flexible, says it all. The trouble is that plastic is just too good. We use it for mostly disposable, low-value items such as food-wrap and product packaging, but there’s nothing particularly disposable about most plastics. On average, we use plastic bags for 12 minutes before getting rid of them, yet they can take fully 500 years to break down in the environment (quite how anyone knows this is a mystery, since plastics have been around only about a century).

In Britain alone (one small island in a very big world), people use 8 billion disposable plastic bags each year. Burning them can give off toxic chemicals such as dioxins.While collecting and recycling them responsibly is also difficult. Getting rid of plastics is extremely difficult. Because there are many different kinds and each has to be recycled by a different process. If we used only tiny amounts of plastics that wouldn’t be so bad, but we use them in astounding quantities. If you’ve ever taken part in a beach clean, you’ll know that about 80 percent of the waste that washes up on the shore is plastic. It including bottles, bottle tops, and tiny odd fragments known as “mermaids’ tears.”

We’re literally drowning in plastic we cannot get rid of. It’s been estimated that 200,000 barrels of oil are used each day to make plastic packaging for the United States alone.And we’re making most of it from oil—a non-renewable resource that’s becoming increasingly expensive.

Making better plastics

Ironically, plastics are engineered to last. You may have noticed that some plastics do. Gradually, start to go cloudy or yellow after long exposure to daylight (more specifically, in the ultraviolet light that sunlight contains). To stop this happening, plastics manufacturers generally introduce extra stabilizing chemicals to give their products longer life. With society’s ever-increasing focus on protecting the environment, there’s a new emphasis on designing plastics that will disappear much more quickly.

Broadly speaking, so-called “environmentally friendly” plastics fall into three types:

Biodegradable plastics made from traditional petrochemicals, which are engineered to break down more quickly

Bioplastics made from natural materials such as corn starch

Eco/recycled plastics, which are simply plastics made from recycled plastic materials rather than raw petrochemicals.

We’ll look at each of these in turn.

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