Thermoplastics
What makes thermoplastics so versatile? Everything about properties, processing, advantages and areas of application – explained concisely and clearly.
Thermoplastics are a class of plastics characterised by their ability to be deformed under the influence of heat. Unlike thermosets, thermoplastics can be repeatedly melted and reshaped without losing their basic chemical structure.
This property makes them ideal for numerous applications in which recycling and flexible shaping play a role.
The manufacturing process of thermoplastics involves melting and shaping the material, which gives them their characteristic properties.
The advantages of thermoplastics include their good processability and their recyclability, while disadvantages include their often limited thermal and chemical resistance.
Fundamentals and properties
Thermoplastics consist of linear or branched polymer chains that do not have permanent chemical cross-linking. This structure allows the molecular chains to loosen and melt when heat is applied, making the material deformable.
On cooling, the material solidifies again, retaining its new shape. This process can be repeated any number of times, as long as the material is not thermally or chemically degraded.
The notable properties of thermoplastics include:
- Reshapability: Thermoplastics can be melted by heating, deformed and then cooled, taking on a new shape.
- Recyclability: Because of their thermal deformability, thermoplastics can easily be recycled and formed into new shapes.
- Lightweight: Thermoplastics are relatively light compared with metals or thermosets, which makes them ideal for applications where weight matters.
- Limited heat resistance: Unlike thermosets, thermoplastics are stable only up to a certain temperature and can melt or deform at higher temperatures.
- Good chemical resistance: Some thermoplastics are resistant to chemicals and solvents, which makes them suitable for certain industrial applications.
Application in industry
Thermoplastics are widely used in industry and in everyday life, as they can be formed into a wide variety of shapes. Examples of applications include:
- Packaging industry: Bottles, films and containers are frequently made from thermoplastics, as they are easy to shape and recycle.
- Automotive industry: Thermoplastics are used for bumpers, dashboards, tanks and other components.
- Construction industry: Window frames, pipes and insulation materials are often made from thermoplastics such as PVC.
- Electronics industry: Thermoplastics are used in housings, cable insulation and circuit boards.
Manufacturing process
The manufacturing process of thermoplastics is based on the repeated thermal deformability of the material. There are several common methods for processing thermoplastics:
- Extrusion: In this process, the thermoplastic is melted and pressed through a die to produce continuous profiles such as pipes or films.
- Injection moulding: The molten plastic is injected into a mould, where it cools and takes on the shape. This process is frequently used for the production of complex parts such as automotive components.
- Thermoforming: A heated plastic sheet is pressed into a mould to produce products such as packaging or housings.
- Blow moulding: In this process, a molten plastic tube is blown into a mould to create hollow bodies such as bottles or tanks.
Thermoplastics in the automotive industry
In the automotive industry, thermoplastics are widespread because of their lightweight construction and processability. They are used in bumpers, dashboards and body parts, where their ability to form complex shapes and be recycled is valued.
Their low weight helps to reduce the overall weight of vehicles, which lowers fuel consumption.
The various thermoplastics
There is a wide variety of thermoplastics that are used in different industries and for different applications. The best-known thermoplastics include:
- Polyamide (PA): A wear-resistant and tough plastic that is used in the automotive industry as well as in the manufacture of gears, bearings and technical components.
- Polyamide 6 GF30 (PA6 GF30): Glass-fibre reinforced and particularly robust, this thermoplastic is used in applications that require high rigidity, such as automotive components and machine parts.
- Polyoxymethylene (POM): A hard and abrasion-resistant plastic with good dimensional stability, frequently used for precision parts such as plain bearings and gears.
- Polypropylene (PP): A light, resilient thermoplastic that is often used in the automotive industry and in the manufacture of containers, furniture and household goods.
- Polystyrene (PS): An inexpensive, rigid plastic that is frequently used for packaging materials, disposable products such as cups and plates, and insulation materials.
- Acrylonitrile butadiene styrene (ABS): An impact-resistant and robust plastic that is used for toys, electronic housings and automotive parts.
- Polyethylene terephthalate (PET): Frequently used for the manufacture of bottles and textile fibres, PET is distinguished by its strength and chemical resistance.
- Polyetheretherketone (PEEK): A high-temperature-resistant and chemical-resistant plastic that is used in demanding applications such as aerospace and medical implants.
- Polyvinylidene fluoride (PVDF): A UV-resistant and chemical-resistant thermoplastic that is used in the chemical industry for pipes, membranes and other corrosion-resistant applications.
Properties and applications at a glance
| Thermoplastic | Properties | Applications |
|---|---|---|
| Polyamide (PA) | Tough, wear-resistant, chemical-resistant | Gears, bearings, technical components |
| Polyamide 6 GF30 (PA6 GF30) | Glass-fibre reinforced, high rigidity, robust | Automotive parts, machine parts, housings |
| Polyoxymethylene (POM) | Hard, abrasion-resistant, good dimensional stability | Precision parts, plain bearings, gears |
| Polypropylene (PP) | Light, heat-resistant, robust | Automotive parts, containers, furniture |
| Polystyrene (PS) | Light, rigid, inexpensive | Packaging, disposable products, insulation materials |
| Acrylonitrile butadiene styrene (ABS) | Impact-resistant, robust, easy to shape | Toys, electronic housings, automotive parts |
| Polyethylene terephthalate (PET) | Transparent, strong, chemical-resistant | Bottles, textile fibres |
| Polyetheretherketone (PEEK) | High-temperature-resistant, chemical-resistant | Aerospace, medical implants |
| Polyvinylidene fluoride (PVDF) | Chemical-resistant, UV-resistant, stable | Chemical plants, pipes, membranes |
Frequently asked questions (FAQ)
What are the main applications of thermoplastics? Thermoplastics are frequently used in the packaging, automotive, construction and electronics industries, as they are light, malleable and recyclable.
How are thermoplastics manufactured? Thermoplastics are manufactured by melting and shaping polymer chains that do not have chemical cross-linking. They can be processed by methods such as injection moulding, extrusion or blow moulding.
What advantages do thermoplastics offer? Thermoplastics offer high flexibility in shaping, recyclability and versatile possible uses. They are light and chemical-resistant.
Are there disadvantages to using thermoplastics? Yes, thermoplastics have limited thermal resistance and can melt or deform at high temperatures. They are also often less stable than thermosets.
Why are thermoplastics so important in the automotive industry? Through their low weight, thermoplastics help to reduce the overall weight of vehicles, which lowers fuel consumption. They are also flexibly malleable and recyclable, which is an advantage in series production.
Thermoplastics are therefore essential materials that play a central role in many industries because of their reshapability, their lightness and their versatile possible uses.
