Chemical cilia felt is often subjected to various external forces such as stretching, crimping and torsion in the process of processing, which makes the fibers change their original shape. Because wool has good elasticity, wool felt tries to restore to its original form, so it produces various stresses inside the fibers. This internal stress needs to be gradually attenuated for a long time until it is eliminated. It often causes difficulties in wool processing, which is also one of the factors of instability in size and shape of wool products in the process of processing and use. The plasticity of wool refers to the property that wool can rapidly attenuate its internal stress under hot and humid conditions and change its existing shape according to external force, and then keep its shape after cooling or drying.
The main break of wool fibers is the cortex composed of cortical cells. There are two kinds of proteins in wool felt cortical cells: high sulfur and low sulfur. The former is the main component of the matrix, and its molecular chain is amorphous curly. The latter has a helical structure, which makes up the basic fibril in the cortical cells. Fundamental fibers form microfibrils, and microfibrils further form microfibrils. All kinds of fibrils are embedded in the tomb, and the fibrils can be connected with the quality by disulfide bond. Some studies indicate that the diameter of fibrils in 0 cortical cells is about 0.25m, the diameter of microfibrils is 7.5nm (75A), and the diameter of basic fibers is about 2nm.