Plastics affect our lives. After all, many everyday utensils are made of plastics, even those you wouldn’t expect. Materials such as aluminium or metal often reach their limits because they effect a higher weight and prevent a flexible usability. Flexibility is also becoming increasingly important in industrial processing, just like a lower final weight.
Plastics consist mainly of macromolecules and are further processed into moulded parts, semi-finished products, films or fibres. Their important technical properties: hardness, breaking strength, formability, elasticity, temperature, heat and chemical resistance. This characteristics can be varied by the choice of macromolecules, the manufacturing process and the admixture of so-called additives.
Plastics are classified into three types according to their physical properties: Thermoplastics, thermosets and elastomers.
Thermoplastics (thermo= warm, hot and “plast” from the ancient Greek plássein = form, mould) are also known as plastomers. They can be deformed in a certain temperature range (thermoplastic). This process is possible as often as desired by cooling and reheating, as long as the thermoplastic material not overheated. Otherwise the material begins to decompose thermally. This material behaviour is a unique selling point, because thermosets cannot be deformed again after curing. Another property that thermoplastics have ahead of other types of plastic: Thermoplastics can be welded.
Thermosets are plastics that retain their condition and shape after curing. This is because their polymers can no longer dissolve due to spatial crosslinking. You can use Thermosets for example in electrical installations due to their mechanical and chemical resistance, even at higher levels of temperatures. The thermosets that are processed most frequently and longest are phenoplastics. Polyester resins, polyurethane resins for paints and surface coatings and virtually all synthetic resins such as epoxy resins are also thermosets.
The following table lists the differences between thermoplastics and thermosets in the manufacturing process.
The third category of plastics is elastomers. Elastomers are plastics that deform elastically under both tensile and compressive loads and then return to their original shape. They occur for example as material for tires, rubber bands, etc.