Plastic is incredibly versatile. From brittle polystyrene cups to engine parts on jet aircraft, plastic can work for various applications. But it requires different types of resins, additives and manufacturing techniques to get the varying results. One of the most common differences between plastics is whether they are thermoplastics or not.
What are thermoplastics?
If you boil or fry an egg, it hardens and takes on new properties. In contrast, you can melt cheese with heat and it solidifies when it cools down. It responds entirely differently to heat than an egg does.
Thermoplastics are like cheese. It’s a plastic that melts when heat is applied and cools into a hardened shape. The opposite is a thermoset plastic, which is baked (or ‘cured’) at high temperatures.
How are thermoplastic objects created?
Thermoplastics can be used in a number of ways. Some resins are so responsive to heat that they soften when in contact with hot water. But most thermoplastic products are created using rotational moulding and injection moulding. In the former, the resin is slowly rotated inside a mould, while in the latter the resin is injected at high pressure into a mould.
The choice of which depends a lot on the object you are making, the speed and scale of manufacturing, and technical details such as the size and purpose of the piece.
What are thermoplastics used for?
Thermoplastics are the most common plastics around. You’ll find most of the plastic objects near you are thermoplastic in nature.
Such plastics are quite flexible and less likely to crack. The plastic itself can be reusable, depending on certain properties. Thermoplastic objects can also be faster to produce, so they are good for mass production, while the high level of finish works well for consumer products. Think of toys or electronic goods: these often use thermoplastics because of the above reasons.
So why aren’t all plastics like this? Thermoplastics are not good with high heat levels, such as parts that sit inside a car’s engine compartment. Nor are they very resilient against long-term UV exposure and other corrosive elements. Though some properties can be added through additives, thermoplastics simply aren’t as hardy as thermoset plastics.
But the necessary qualities depend a lot on what the final product will be used for and the manufacturing technique used to create it. Thermoplastics are ideal for a great many uses in today’s world.