Different kinds of plastic are made for different purposes and they are produced in different ways. One type of plastic is called thermoplastics. As you can see in the picture below, this is used for lots of different products that you can find in the supermarket. Today I will explain what thermoplastics are and what you can do to avoid them.
The basis: crude oil
Most plastics are made of crude oil. Or actually, just of a small part of the crude oil. In a refinery, crude oil will be separated in different fractions. One of this fractions is naphtha.
Naphtha is heated at approximately 900 degrees Celsius. With this process naphtha will fall apart in small carbon pieces. The carbon pieces look like beads.
Next, these beads go to a chemical plant where they are combined into long strings. By putting the beads on a thread the beads will stick together and you can twist them together. That’s how thermoplastics look like when you take a look at them under a microscope.
Different chemicals are added for different products
Thermoplastic objects are made by molding or by casting. Small plastic grains are heated and then injected in a mold.
By adding different kind of chemicals to the process, different types of plastic are made. Some of these are very flexible and thin, they are used for plastic wrap. Others are more stiff, they are used for tubes or bottles.
There are many different kinds of thermoplastics. You may have noticed that plastic products have a small triangle with a number in it. The number indicates the type of plastic.
Easy to recycle in theory, but not in reality
Thermoplastics are relatively flexible. This plastic will become soft when heated. That’s the reason why it’s easy to recycle. This plastic can be melted again and reused to make new products of it. Yet, after threating our health, loads of thermoplastics end up on the streets and eventually in our waterways and oceans. There, animals will ingest it, leading to (slow) death and/or toxic fish that ends up on our plates.
Plastic is FOREVER! It breaks down into ever smaller pieces
The plastic industry has always been telling us that plastics are inert so it will last forever and will not affect our environment. When we look at the amount of small plastic parts we find in the water we know that plastic is not inert. Just put a plastic bag of LDPE in your garden for about a year and let the sun and rain do their job. After approximately a year you will find the bag crumble into very small pieces. That’s not really inert.
Plastic harms our health
In the long run all plastics will leak acetaldehyde. Because of the fact that almost everything that is produced contains plastics, acetaldehyde is a common contaminant in workplaces, indoors, and in ambient environments. It is also a potential carcinogen. Moreover, we spend more than 90% of our time in indoor environments, hence increasing any exposure and, as a consequence, the risk to our health.
Worst offenders: PVC, disposable tableware, and styrofoam!
2 things you can do
1. Definitely avoid PVC!
Lead compounds are used to stabilize PVC. The selling of lead stabilizers will end by 2015, until then it can and will be used in the production process of PVC.
Because plastic stays around forever, PVC with lead will also be around for ages to come. As known, lead is very dangerous for our health and the environment.
Another negative side of PVC is the fact that when it is burned there will be a release of dioxin. A small amount of dioxin can have the effect of disrupting the hormone balance of animals and humans.
2. Refuse disposable tableware and styrofoam!
Polystyrene is used for making disposable tableware as well for styrofoam. When polystyrene is heated it will leak toxic substances such as styrene and benzene. So when you use disposable tableware in your microwave there will be a change that you get these substances in your food. Styrene and benzene are known as carcinogenic. They too effect our hormonal balance.
Polystyrene is a plastic that is easy to make, cheap and has a lot of application possibilities. Because of that its production is growing year after year. Right now 71% of plastic that is found in the ocean is made of this type of plastic.
So even if you are not yet ready to give up all plastics, try to avoid these two as much as you can.
Want to learn more about plastic? Next time I will write about thermosetting plastics, that’s the plastic that can’t be recycled. Of course, if you have any questions about plastic, please let me know (leave a message below) and I’ll try to answer.
Wishing you all a wonderful week! Plastic-free of course!
This post was written by Barbara, a chemical engineer living in the Netherlands. She was in charge of the crash course Plastics: The Basics. Barbara writes about what plastic is, where it comes from, what the difference between a plastic bottle and plastic wrap is, and what to think of chemical additives such as BPA.