All plastics are not the same. We touched on this topic in our blog What is Plastic Resin?, but it is a fascinating topic that deserves a little more detail. So let’s look at five different plastic materials that are popular for injection moulding projects.
ABS, shorthand for the tongue-twisting Acrylonitrile-Butadiene-Styrene, is all around us. The keys on a keyboard, faces for light switches, car dashboards and trim, even those Lego pieces you wish you could see on the floor, are all manufactured from ABS.
As the examples indicate, ABS can be quite tough and resistant to wear, even against modest heat and chemicals. It’s a popular choice for design, as it is an easy plastic to manipulate and glue. It also recycles well, making ABS considerably cheaper than most other plastics.
Polypropylene is very common: you’ve sat on it, stuffed groceries into it and filed pages between sheets of it. It’s the bottle you open for headache pills and the noisy toy that has been giving you a headache.
PP is not better at any one thing than other plastics. But it scores consistently well across many attributes and can even be reasonably translucent. It is also very forgiving and can be used in a wide variety of fabrication techniques.
Nylon was the first successful synthetic thermoplastic polymer, aka. the first melting-point plastic that was successfully sold into the market. That started as bristles on toothbrushes, but today nylon can be found in countless products in fibre, film and solid forms.
Nylon is not a specific product, but actually the name for plastic ‘polyamides’. Polyamides are made of a specific chemical arrangement and can occur naturally, such as in wool or silk. The synthetic plastic version of this chemistry is called nylon. Nylon is durable, elastic and easy to wash. It is quite common inside engine compartments due to its resilience against heat and chemicals.
What does dodging a bullet and playing a DVD have in common? Polycarbonate or PC. Both the plastic from DVDs and the plastic used to create bullet-proof ‘windows’ are made from this hardy substance. It’s a tough plastic also coveted for its natural translucency.
The ability of PC to convey light can be as good as glass, yet it can be moulded into a large variety of shapes, such as light covers for cars. PC can also be coloured and even made opaque. Combine it with flame-retarding additives and it becomes a very formidable substance
Polystyrene brings to mind that flakey balls compressed into appliance packaging. This happens when General Purpose Polystyrene (GPPS) is foamed. But it can also be solid and is used for everything from action figures to medical devices.
GPPS is a very common choice for injection moulding, as it is very agreeable when heated into a liquid. That means it is easier to manage during the injection moulding process than many other plastics, particularly for objects that have a lot of small detail.