Major features of plastics are their technical properties, such as mouldabiliity, hardness, elasticity, breakage resistance, temperature resistance, heat distortion resistance and chemical resistance, which can be varied widely by the choice of macromolecules and manufacturing processes and – in most cases – by incorporating additives. As far as their physical properties are concerned, plastics can be divided up into three main groups: thermoplastics, thermosetting plastics and elastomers.
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Thermoplastics (based on the ancient Greek words θερμός thermós = warm, hot and πλάσσειν plássein = form, mould), also known as plastomers, are plastics that can be moulded in a specific temperature range (thermoplastic). This process is reversible, i.e. it can be repeated as often as required by cooling and reheating to the molten state, unless what is known as thermal decomposition of the material begins due to overheating. This is what distinguishes thermoplastics from thermosetting plastics and elastomers. Another unique feature is that thermoplastics can be sealed.
Thermosetting plastics are plastics that cannot be moulded any more after they have cured. Thermosetting plastics are hard, glassy polymer materials that are permanently cross-linked three-dimensionally via chemical main valence bonds. The cross-linking takes place during the blending of upstream products with branched junctions and is activated either chemically at room temperature with the help of catalysts or thermally at high temperatures.
Elastomers are dimensionally stable plastics that are, however, elastically mouldable and have a glass transition point that is below the application temperature. The plastics can change their shape elastically under tensile stress and pressure, but return to their original, unformed state afterwards. Elastomers are used as materials for tyres, rubber bands, sealing rings etc. The most well-known elastomers are vulcanised natural and silicone rubber.Elastomere (Sing. das Elastomer, auch Elaste) sind formfeste, aber elastisch verformbare Kunststoffe, deren Glasübergangspunkt sich unterhalb der Einsatztemperatur befindet. Die Kunststoffe können sich bei Zug- und Druckbelastung elastisch verformen, finden aber danach wieder in ihre ursprüngliche, unverformte Gestalt zurück. Elastomere finden Verwendung als Material für Reifen, Gummibänder, Dichtungsringe usw. Die bekanntesten Elastomere sind die Vulkanisate von Naturkautschuk und Silikonkautschuk.