The elastic deformation of fibers can be divided into three categories based on their recovery ability and mechanism of action: rapid elastic deformation, slow elastic deformation, and plastic deformation, which together determine the wearability and durability of textiles.

1. Rapid elastic deformation (reversible elastic deformation)

Rapid elastic deformation refers to the deformation of fibers immediately under external force, and the complete recovery of deformation immediately after the external force is removed. This deformation originates from the changes in bond angles and small segment movements of fiber polymer chains, without consuming energy or generating heat. Spandex can quickly rebound after stretching, making it an ideal material for tight fitting clothing. The range of rapid elastic deformation is usually between 1% and 5%, and beyond this range, it will enter the stage of gradual elastic deformation.

2. Delayed elastic deformation

When the external force is applied for a long time or the deformation is large, the fiber will undergo slow elastic deformation. At this point, the molecular chain segments undergo slippage and rearrangement, and it takes some time to gradually recover after removing external forces.

3. Plastic deformation (permanent deformation)

When the external force exceeds the elastic limit of the fiber, the molecular chain undergoes irreversible displacement and fracture, resulting in permanent deformation. Plastic deformation can reduce the strength and service life of fibers, so tension control is necessary in textile processing to avoid excessive stretching.