Why thermocol is discouraged for making science models?

Answer 1

Thermocol or thermocole, as I believe it originally was spelt, is a trade name for a class of plastics called polystyrenes. They are very cheap and very useful in a number of ways, and in some forms they can be used in making miraculous plastics in combination with related compounds like butadiene and acrylonitrile. You probably are familiar with polystyrenes in forms such as the outer cases of computers, and in packaging such as expanded polystyrene foams (but watch out! Not all plastic packaging foams are polystyrenes!) and some kinds of transparent wraps.

Polystyrene is made from styrene (which may be called styrene monomer, you have to chain a lot of monomers to make a polymer like polystyrene). Styrene is a chemical rather like benzene or toluene (and if you don't know those two, it is sorta-kinda like gasoline (petrol if you are not from the US)). It is not healthy to drink or breathe it, so it is sensible to be cautious in what you do with it. It has a low acute toxicity, but it does present health risks when there is chronic exposure. Same for gasoline. It is bad for your liver, lungs, and cells that may be influenced into becoming cancerous. We say that it can be oncogenic or carcinogenic.

Now, polystyrene is not the same as styrene just because it is made from styrene, any more than a house is the same as a brick because a house is made of bricks, so the main risk in using polystyrene is from breathing in or eating small amounts of the styrene monomer, and that is not a large risk for any normal use; I have never heard of anyone's cancer being traced to domestic use of polystyrene. In fact there is precious little health risk associated with working with finished polystyrene products at all. Some kinds of cardboard and plywood would be worse.

Some people make a fuss about the carbon content and energy content of polystyrene, because it is made largely of non-renewable fossil fuel resources, but really, anyone who uses a car or flies in a commercial plane, or burns electric lights from a fossil fuel power station, is consuming or even wasting fossil carbon far faster than they are saving it by avoiding the use of polystyrene.

Well, another problem is that polystyrene does not rot easily in dumps or underground, and when it does rot, the products in turn are not very friendly to soil organisms like those bacteria and fungi that should in turn rot it further into good biochemical food like carbohydrates and fats. I suspect that a case from a discarded computer display might last underground for centuries or even millennia in suitable soil. However, if one saves it instead of dumping it, solid polystyrene of most kinds is easy to recycle, partly because it does not spoil and rot quickly and it can be dissolved and generally is easy to work with.

A more serious problem is with expanded polystyrene. That is the stuff that they can use to package Hamburgers and other convenience foods (or could; in some places it is now forbidden). Other versions of it you might use in projects because it is light and cheap and easy to cut and melt, either with knives, saws, or hot wires. You will know the smell I suppose? There also is a slight fire hazard, though nothing like working with kerosene or benzine. Frankly, if you are careful and see that you have good ventilation and control of flames and so on, the hazard is very low indeed. If you are doing a lot of such work it might be sensible to wear a good face mask to to keep dust out of eyes and lungs, but such masks are good to wear even working with large quantities of wood or cotton

One of the main problems with expanded polystyrene is that it needs special procedures for recycling. You will read in various places that it cannot be recycled, but that is nonsense now and was nonsense when it first was said. It certainly was not possible by the old means of recycling, but newer methods of recycling are now well established and are coming into wider use.

So: is there any special reason to discourage the use of polystyrene, particularly in science projects? No, certainly not as a rule.

For a start, all the science projects around the continent in any one year wouldn't equal the amount still used in packaging junk food in one night. Secondly, the personal hazards are easily avoided by the very sorts of precautions that should be observed in any science project using any material whatsoever, and:

Thirdly, the recycling problems are manageable and proper use of the resources prevent waste of other, more precious resources, such as good wood for example.