Elastomer - Elastomer (English spelling)

A general term for polymeric substances that exhibit rubber elasticity at room temperature. A compound term of elastic and polymer. Rubber can be divided into raw rubber (raw rubber) and elastomers (rubber elastic body/vulcanized rubber). Raw rubber is generally a highly flexible amorphous chain polymer, and external forces cause intermolecular displacement, and when the external force is removed, some of the molecules do not return to their original shape. In other words, it exhibits plasticity. On the other hand, elastomers have a three-dimensional network polymer structure in which raw rubber is gently cross-linked, and have the property of being greatly deformed by small external forces (elastic modulus of 1-3 megapascals, elongation several times), and immediately returning to their original shape when the external force is removed. Elastomers are substances that exhibit rubber elasticity, allowing for reversible deformation. In contrast, substances that do not return to their original shape when deformed and exhibit plasticity are called plastomers.

[Kazuyoshi Fukuda]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

常温付近でゴム弾性を示す高分子物質の総称。elastic（伸縮性のある）とpolymer（重合体）を合成した用語。ゴムは生ゴム（原料ゴム）とエラストマー（ゴム弾性体・加硫ゴム）に分けて考えられる。一般に生ゴムは屈曲性の高い非晶性鎖状高分子であり、外力によって分子間にずれが起こり、外力を除いたときに一部は元に戻らなくなる。すなわち塑性を示す。一方、エラストマーは生ゴムがゆるやかに架橋した三次元網目状高分子構造をもち、小さな外力で大きく変形し（弾性率は1～3メガパスカル、伸びは数倍）、外力を除くと、ただちにもとの形に戻る性質がある。エラストマーは、可逆的な変形が可能なゴム弾性を示す物質である。これに対して変形がもとの形に戻らず塑性を示す物質はプラストマーという。

［福田和吉］

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