Fabric heat setting can be divided into three stages. The first stage is a "relaxation" stage using heat or plasticization (plasticizers such as water and steam)
In this method, the fiber is made higher than the glass transition temperature and the force existing between molecules is weakened.
The reduction of the region occurs only in the amorphous region, while the persistent supramolecular structure (crystalline region) does not decay or crack.
The second stage is the solidification stage, in which some active groups in macromolecules meet the same groups in other macromolecules, approaching the interaction distance between atoms.
New keys are formed. At this time, these bonds are unstable due to high temperature, but the intermolecular force gradually increases as the number thereof increases.
At a higher stage, further crystallization will occur, thus reducing amorphous regions and improving crystallinity and crystallinity.
The second stage takes more time than the first. The speed of the second stage depends on the mobility of macromolecular chains or segments, i.e. the heat setting temperature.
The third stage is the fixing stage, in which the fibers are cooled to below the glass transition temperature or the plasticizer is removed (dried), at which time the position of the new polymer can be completely fixed.
The fixing stage of the Hot Air Stenter Machine can be completed in a few seconds, depending on the process of gradually cooling or removing the diffusion rate of plasticizer.