Mechanism and process of heat setting(一）
Fabric heat setting can be divided into three stages. The first stage is the "slack" stage, using heat or plasticization (plasticizers such as water and steam)
In this method, the fiber is made to be higher than the glass transition temperature, and the force existing between molecules is weakened.
The reduction of zone occurs only in the amorphous region, while the longer-lasting supramolecular structure (crystalline region) is not attenuated or broken apart.
The second stage is setting stage, some active groups in the macromolecule meet the same groups in other macromolecules, close to the distance to the interaction between atoms,
A new bond is formed. At this time, due to the high temperature, these bonds are unstable, but as their number increases, the intermolecular forces gradually increase.
In the high stage, further crystallization will occur, reducing the amorphous area, and improving the degree of crystallinity and crystallization.
At second stage takes more time than the first stage.The speed of the second stage depends on the mobility of the macromolecular links or segments, that is, on the heat-setting temperature.
The third stage is a fixed stage, the fiber is cooled below the glass transition temperature or the plasticizer is removed (dried),at this moment the position of the new macromolecular can be fixed completely.
The fixation phase can be completed in seconds depend on the process gradually cooling or removing plasticizers speed of diffusion.