Today they are on everyone’s lips: plastics. Without them, modern life would be inconceivable: plastic packaging ensures a long shelf life for food, temperature-resistant plastics enable lightweight vehicles and e‑mobility, cable sheathing protects sensitive electrical cables – to name just a few examples. A look at chart 1 shows the sectors in which the production volume of 54 million tons of plastics in Europe in 2022 ended up.
Source: Plastics Europe
Origin of plastics
Yet this material is not that old. It was not until 1920 that Hermann Staudinger recognised the concept of long-chain macromolecules. This discovery was the starting signal for a group of materials that has developed rapidly. Over 200 different plastics have been created in just over 100 years.
However, not all plastics are the same. What they all have in common are the long-chain carbon compounds – sometimes chains arranged next to each other, at other times entangled or in rings. Other molecules often attach to the carbon chains. They strongly influence the length and structure of the carbon chain, but also the properties of the plastic.
Thermoplastics, elastomers and thermosets
Plastics can basically be divided into three categories: thermoplastics, elastomers and thermosets. Thermoplastics transform into a flowable, plastic state when heat is applied and are easy to process. They include polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyamides (PA), polycarbonates (PC) and polyethylene terephthalate (PET).Elastomers such as rubber and caoutchouc are very elastic. They cannot be melted because their macromolecules are connected to each other at some points and form a wide-meshed spatial network. In thermosets, the macromolecules are closely interlinked in all spatial directions. This makes them very hard and non-meltable. Thermosets are created from two liquid starting products that react with each other. These include polyurethanes (PUR) and epoxy resins, for example.
Thermoplastics
Thermoplastics are the plastic of choice in numerous applications. They are easy to process and – depending on the respective thermoplastic and its additives – have a wide range of properties. This is important, because in “real life” it’s what really counts: what temperatures can the thermoplastic withstand? How stable is it, what sliding properties does it have, how can it be processed into the desired product and – another not-inconsiderable factor – how much does it cost? The so-called plastic pyramid has developed from this bundle of challenges. Here you can see at a glance which thermoplastic is suitable for a particular application. The pyramid is divided into standard plastics, engineering plastics and high-performance plastics.
Chart 2: Plastic pyramid: The performance of the materials increases from the bottom to the top of the y‑axis, while the production volume decreases.
Source: Wikipedia
While the top of the pyramid is made up of high-performance materials that can often withstand 300 °C, standard thermoplastics such as PE or PS play in the 80 °C league. High-end plastics such as PAI are often used to produce precision parts for electronic or medical devices. PEEK components are used in gearboxes, cogwheels and seals in the automotive and aerospace industries. Standard thermoplastics make up the lion’s share of plastics. From packaging to bumpers, dashboards, caravan or train panelling and household appliances. Engineering thermoplastics comprise a large class of plastics. The name gives it away: many of them are used in technical products, as their performance lies in the mid-range between the top and the bottom of the pyramid. Applications in the construction sector, in the engine compartments of fuel tanks and fuel lines, structural components of car bodies or lamp housings are just a few uses for PA and POM. PC and PMMA are often used as glass substitutes for lights, lenses and medical applications. The temperature resistance of engineering thermoplastics ranges from ‑60 °C to peaks of 260 °C, depending on the material. Unsurprisingly, the materials at the top of the pyramid are very expensive; as you move to the base of the pyramid, the price drops accordingly.
Production Volume of Plastics Increases Worldwide
High-performance plastics and engineering plastics are only ever used when standard materials are not up to the demands of daily use. The amount of plastics produced worldwide reflects this. 400.3 million tonnes of thermoplastics were produced worldwide in 2022, a good 63% of which are standard plastics (see Graph 3). The higher up the plastic pyramid you go, the lower the market share.
The amount of plastic produced worldwide has risen sharply over the last 70 years. Waren es laut Statista 1950 gerade mal 1,5 Mio. Tonnen weltweit, sind es heute fast 270 Mal so viel.According to Statista, in 1950 there were just 1.5 million tonnes worldwide, but today there is almost 270 times as much. The drivers of this increase are in Asia, especially China. In Europe, the amount of plastics produced has stagnated over the last ten years.
Plastic recycling against plastic pollution
An infinite number of applications are inconceivable without plastics. And yet macromolecules have an inherent curse: they last an extremely long time. According to NABU, a plastic bag takes 20 years to decompose, a plastic bottle a full 450 years and a fishing line remains in the sea for up to 600 years. Endless plastic “carpets” on the ocean floors make the problem abundantly clear. For this reason, the recycling of plastics and the establishment of a functioning circular economy are essential. As can be seen in chart 3, 9.5% of plastics are currently based on recycled materials. We at ENNEATECH are convinced that this is not enough. With our recycled polyamides, we are making a contribution to more sustainable, climate and environmentally friendly plastics production.
