The reason why rubber has high elasticity

The elastic deformation of rubber is derived from the fact that the bonds in its macromolecular molecular chain are relatively easy to rotate. Under the action of external force, the whole macromolecule is easily deformed because its rotational barrier of the bond is relatively low, so the modulus is low, after the external force is removed. Because the molecular thermal motion is easy to automatically restore the original deformation, that is, the direction of entropy increases, the rubber is stretched to lower the entropy of the system and become hot. The elastic deformation of gold M is derived from the change in bond length and bond angle between its atoms, so the modulus is reduced and the tension is cooled.

The specific performance of rubber high elasticity

What is the degree of high elastic deformation, and at what speed, and to what extent, after removing the external force, can it be defined as rubber? ASTM D1566 is defined as follows: Rubber is a material that recovers its deformation quickly and forcefully under large deformations. It can be modified, and the modified rubber is substantially insoluble (but swellable) in a solvent such as boiling benzene, methyl ethyl ketone or ethanol-toluene mixture. The modified rubber is stretched to 2 times the original length at room temperature (18 to 29 ° C) and removed for 1 min to remove the external force, which can recover to less than 5 times the original length of h within 1 min.

The modification referred to in the definition refers to vulcanization. The lightly crosslinked rubber is a typical elastic material. The rubber is an organic germanium molecular material, so it has the commonality of such materials: such as low density and good insulation. It is not easy to be corroded by acid or alkali, and has low permeability to fluids, but its strength is relatively low, the hardness of the hard slope is low, it is not so wearable, and it is not resistant to environmental aging.