Unitl about myself

1. Thermoplastics soften on heating, then harden again when cooled. Thermoplastic molecules are also 
coiled and because of this they are flexible and easily stretched. 
Typical example of thermoplastics is polystyrene. Polystyrene resins are characterized by high resistance to 
chemical and mechanical stresses at low temperatures and by very low absorption of water. These properties 
make the polystyrenes especially suitable for radio-frequency insulation and for parts used at low temperatures in 
refrigerators and in airplanes. PET (polyethene terephthalate) is a transparent thermoplastic used for soft-drinks 
bottles. Thermoplastics are also viscoelastic, that is, they flow (creep) under stress. Examples are polythene, 
polystyrene and PVC. 
2. Thermosetting plastics (thermosets) do not soften when heated, and with strong heating they 
decompose. In most thermosets final cross-linking, which fixes the molecules, takes place after the plastic has 
already been formed. 
Thermosetting plastics have a higher density than thermoplastics. They are less flexible, more difficult to 
stretch, and are less subjected to creep. Examples of thermosetting plastics include urea-formaldehyde or 
polyurethane and epoxy resins, most polyesters, and phenolic polymers such as phenol-formaldehyde resin. 
3. Elastomers are similar to thermoplastics but have sufficient cross-linking between molecules to 
prevent stretching and creep. 
Vocabulary: 
carbon 
— углерод
flexible 
— гибкий 
fibre 
— волокно, нить 
chain 
— цепь 

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identical 
— одинаковый, идентичный
molecule 
— молекула
branch
— разветвленный