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Afbeelding: Polymeren hoofdfoto 1

Polymers, the construction of plastic

15 December 2020

Plastic, a material that is essential for the industrial industry. But what exactly is plastic like? In this article we explain more about the structure of plastic, or; polymers. We describe the different types of plastics, their characteristics and the advantages of their use. 

The origins of polymers

Plastic is created by a chemical compound, which is made by a non-natural chemical process. Plastics are polymers, these are repeated molecules, which are also called monomers. The repeating molecules form the basis. A polymer often consists of thousands of monomers which makes it incredible long. They have been found in nature for a long time, think of the starch in potatoes, the cellulose in wood and the proteins in animals and plants. The industry has copied the trick of polymers from Mother Nature. You can see the result in the form of all kind of plastics.

Different kind of plastics

There are many types of plastics, all with different characteristics. Bendable or not, light or heavy weight, elastic or not, resistant to higher temperatures and so on. The characteristics of plastic are determined by the monomers, which forms the polymer again. You have different types of polymers, which you can read below.

Afbeelding: plastic recycling

Thermoplastics and thermosets

Thermoplastics

A thermoplastic is a plastic material that becomes soft when heated. A thermoplastic has long molecular chains, so-called polymers. Molecules lie tightly together with a solid form of plastic. When the thermoplastic is heated at approx. 165 °C, the molecules become more mobile. It is therefore a material that deforms and liquefies when heated. At a cooling point of approx. 120 °C, the thermoplastic becomes solid again. The cooling down of a thermoplastic depends on the Tg temperature, which is different for each thermoplastic. You can read about the difference in thermoplastics here.

Thermoplastics are almost always used forinjection moulding. This is because they are fusible polymers, which can be moulded into a mould by means of injection moulding.

An advantage of thermoplastics? The material gives the possibility to reuse, also called recycling. By reheating, the material can be brought into other desired shapes. This can also be helpful for Design For Disassembly (DFD). Think of thermoplastics like foil, bottles, clothing, Styrofoam and many other products

Thermoset

A thermoset is a material that, compared to the thermoplastic, can only form once, after which it remains hard when heated. The cause? The cross-links; cross-links, between the individual chains. The polymers form into a network polymer and often decompose before they melt. Whereas with a thermoplastic the material can still be transformed after processing, the thermoset after processing is not. The dense network structure keeps the polymer chains together. The dense network structure ensures a different processing than with a thermoplastic. Think of products such as power sockets or switches, you want them to remain solid under all circumstances.

The thermoset does not melt, but decomposes without becoming liquid, which makes thermosets difficult to reuse. Thermosets are used less often than thermoplastics because they are harder to produce by injection moulding and are difficult to recycle.

Afbeelding: Stopcontact

The difference between a thermoplastic and thermoset

To give a clear picture, we compare the thermoplastic and the thermoset. The names already indicate that these have something to do with the temperature. Thermoplastics become soft and moveable. Thermosets remain hard and are not flexible. There is no good. Movement in an object made of thermoset. In addition, the difference is that a thermoplastic is easy to recycle, the thermoset is not.

Are plastic and synthetic material the same?

Plastic and synthetic material differ from each other. Plastic is a synthetic material, but not every synthetic material is a plastic. The words plastic and synthetic material are used in practice as synonyms, yet they are different. So, the two differ in structure, solubility and melting point. A plastic is a synthetic material which becomes an object by heating in a form. Also called a thermoplastic. A thermoset cannot be formed by heating and therefore falls under synthetic material.

Advantages of plastic

More and more companies are opting for plastics, it is therefore on the rise in the industry. The durability of plastic is more often preferred to that of steel or stainless steel. There are many advantages to plastic, the most important ones are:

  • Cheaper
  • Fewer parts in the end product
  • Fewer assembly steps
  • Fewer after-effect steps
  • Product weight saving
  • Many different types of plastic with unique characteristics
  • Available in many colors

Contact

In this article we have explained the basics of polymers and plastics, of course there is much more to talk about. Would you like more information about how this works at Rompa? We will be happy to tell you more about it. Don’t hesitate to contact us.