In physics, elasticity means that an object will deform after being subjected to an external force, and when the external force is removed, the object can be restored to its original state. This property is the opposite of flexibility. In physics and mechanics, elasticity theory describes how objects move or deform under the action of external forces.
In physics, elasticity refers to the property that an object is deformed under the action of an external force and can recover its original size and shape when the external force is removed. In solid mechanics, elasticity means that when the stress is relieved, the material returns to the state before deformation.
The external force on the object is within a certain limit, and after the external force is removed, the object can restore its original size and shape; Exceeding the limit, the external force cannot be restored to its original state after withdrawal. This limit is called elastic limit (see tensile and compressive deformation of elastomer). The elastic limit of the same object is not fixed, but decreases with the increase of temperature.
In typesetting and printing, it refers to the ability of rubber blanket to return to its original state immediately after removing the external force of its deformation. In the printing process, when the blanket cylinder comes into contact with impression cylinder, the blanket will be deformed under a certain pressure. When the surface of impression cylinder is away from the surface of the blanket cylinder, the blanket is required to quickly return to its original state before receiving the ink on the printing plate dot, so the blanket must have high elasticity.
Common elastic materials include:
1. Natural rubber: It comes from rubber tree and has excellent elasticity and aging resistance, but poor heat resistance and is biodegradable. Mainly used for manufacturing tires, hoses, rubber sheets, etc.
2. Synthetic rubber: such as styrene-butadiene rubber, neoprene rubber, acrylonitrile rubber, etc. Its performance is better than that of natural rubber, and its performance can be adjusted to meet different purposes. It is one of the most important synthetic elastic materials.
3. Silicone rubber: it has ultra-high temperature aging resistance, wear resistance and weather resistance, but it is expensive.
4. Polyurethane: It has excellent elasticity, wear resistance and shape memory, but poor solvent resistance. Mainly used for manufacturing springs, plastic tires and plastic instruments.