Absorption Capacity
Textile raw materials with the capacity to absorb moisture from the surrounding atmosphere exhibit distinct physical changes during processing and testing. A hygroscopic fibre absorbs water vapour into its internal polymer structure, which alters its mass and mechanical properties. This process occurs through the binding of water molecules to hydrophilic groups within the polymer chains.
Wool and cotton are prominent examples of such materials.
Mechanical Behavior
Moisture absorption directly influences the tensile properties and elasticity of the yarn during spinning and weaving. When a hygroscopic fibre absorbs water, the internal structure swells, which usually reduces the tensile strength of protein-based materials while increasing the strength of cellulosic ones. This swelling also increases the flexibility of the yarn.
Spinning mills must adjust the tension of their machinery to accommodate these shifts in elasticity and diameter. Such adjustments prevent yarn breakage during high-speed knitting.
Commercial Weight
The commercial valuation of raw textile shipments depends heavily on the moisture present in the bale. In transactions involving a hygroscopic fibre, buyers and sellers calculate the dry weight and apply a standard moisture regain percentage. This method ensures that the buyer does not pay for water weight added during transport or storage in humid conditions.
Standardized conditioning is therefore mandatory before final weighing.
Testing Standard
Laboratory assessments must account for the moisture history of the material. A hygroscopic fibre requires pre-conditioning to ensure it reaches moisture equilibrium from a dry state rather than a wet state. This protocol secures consistent results across different testing locations.
