Thermoplastics soften on heating, then harden again when cooled. Thermoplastic molecules are also coiled and because of this they are flexible and easily stretched. Transparent thermoplastic used for soft-drinks bottles.
Thermosetting plastics (thermosets) do not soften when heated, and with strong heating they decompose(разлагаться). Thermosetting plastics have a higher density (тығыз) than thermoplastics.
Elastomersare similar to thermoplastics but have sufficient cross-linking between molecules to prevent stretching and creep. (Эластомеры подобны термопластам, но имеют достаточное соединение между молекулами, чтобы предотвратить протяжение и ползучесть.)
