The Advantages of Thermosetting Plastics in Industry
Plastic materials can be broadly divided into two separate categories: thermoplastics and thermosetting plastics. These two types of plastic constitute the two main forms, sometimes called resins, that plastics when used in industrial manufacturing take on; however, there are other forms that can be utilised when necessary, which will not be detailed here. Plastic injection moulding is one of the major methods for producing plastic materials in industry, and injection moulding almost exclusively uses these two resins.
But what are the differences between thermoplastics and thermosetting plastics? There is a large crossover when it comes to what kind of applications these two resins are used for, but in general thermosets are stronger and more durable, and therefore are used more extensively. They have downsides of course, but their durability is such that they possibly win out in industrial use. But why are they so much stronger?
It all comes down to the bonding between the plastic molecules. Plastics are polymers, which means they are made up of long chains of molecules, thus they can be used for large items. Thermosetting plastics are polymers which irreversibly cure. What this means on a superficial level is that when they reach temperature, which is generally above 200 degrees C, they can be moulded into their final shape, and set permanently once cool. Thermosetting plastics can also be cured using a chemical reaction, or using electron beams and irradiation. Thermosets are usually found in liquid form, or are at the very least extremely malleable, before they are cured.
The moulding process itself uses cross linking to transform the resin into a fully-fledged plastic or rubber. Catalysts and energy, or in some cases only one of these, are applied, which cause the chains of molecules to react at their active sites; that is, the part of the molecule where reactions are able to occur. The molecular chains eventually link into a rigid, 3-D structure. The molecule therefore has a larger molecular weight, and combined with its added rigidity, means that the plastic has a higher melting point.
The reason for the inability to reheat and remould thermosetting plastics is that decomposition, that is the disintegration of the molecular structure, begins to occur before the adequate temperate is reached when reheating. The problem with this of course, is that it is extremely difficult to recycle thermosetting plastic materials, which is becoming more and more necessary in today’s society. However, there are a great many advantages to thermoset, and this is reflected in their wide industrial usage.
Both thermoplastics and thermosetting plastics can be used with the industrial process of plastic injection moulding. plastic manufacturers are in great demand, and are able to employ the advantages of thermosetting plastics to create practical products.
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