Greige Storage Conditions Impact on Subsequent Dye Absorption
Uncontrolled greige storage triggers moisture migration, lipid autoxidation, and sizing retrogradation, which impair surface wettability and cause severe dye absorption variances.
Polyvinyl Alcohol Crystallization
Size Hardening
Increase in the ordered molecular structure of synthetic polyvinyl alcohol sizing occurs when sized yarn is dried at high temperatures. This physical transition, known as polyvinyl alcohol crystallization, makes the sizing polymer highly resistant to dissolution in water during desizing. The polymer chains align and form strong intermolecular hydrogen bonds that act as physical crosslinks.
It must be managed by controlling the dryer temperature and sizing formulation.
Desizing Resistance
When the size film becomes highly crystalline, it does not dissolve easily in the continuous desizing wash. The residual size film remains on the yarn, leading to a stiff hand and preventing dye molecules from reaching the fiber surface. This leads to streaks and light spots after the dyeing stage.
Mill operators must use high-temperature wash baths with surfactant additives to force the size to dissolve.
Thermodynamic Parameter
The degree of crystalline transition is determined by both the drying temperature and the moisture level of the yarn. Keeping the dryer below one hundred and twenty degrees Celsius limits this molecular change.
Process Alternative
Using copolymer grades of the sizing agent can reduce the crystallization tendency. These modified polymers maintain high solubility even after exposure to intense dry heat.