It means that it softens when exposed to heat and hardens again when cooled.

 

It has covalent bonds in the chain and van der Waals bonds within the chain. All polymers exhibit a high stiffness (high modulus of elasticity and high shear modulus) at low temperatures and are brittle.

 

Thermoplasts can melt and dissolve repeatedly. This has a special meaning in terms of environmental protection. Thermoplasts are perfectly suited for recycling as long as the individual types are not mixed with each other. So theoretically, a mudguard could be produced from a few thousand yogurt bowls.

 

One important advantages of thermoplasts is that they can be welded with heat when cracks and fractures occur.

 

Above a certain temperature region called glassing temperature Tg (freezing temperature), chain molecules gain a certain thermal mobility. Thus, the substance becomes more bendable and ductile. However, secondary bonds and knots that occur as a result of movement prevent slipping. The material becomes thermo-elastic.

 

Thermoplasts have temperature-dependent properties:

• Modulus of elasticity
• Strength
• Ductility.

 

If the temperature rises even higher, the primary bonds begin to dissolve one by one, the molecular chains break down and become low-molecular substances. At the end, the material is damaged.