Commercial Regain Corrections in Binary Fibre Blend Analysis
Commercial regain corrections convert oven-dry laboratory residue masses into legal billed weights to prevent customs penalties and tariff misclassification.
Moisture Hysteresis
Equilibrium Deviation
Thermodynamic lag in the moisture content of textile fibres depends on the direction of the humidification process. This phenomenon, known as moisture hysteresis, means that a fibre will hold more water at a given relative humidity when it is drying from a wet state than when it is absorbing water from a dry state. The difference between the adsorption and desorption curves is characteristic of the specific fibre type.
Physical Mechanism
Swelling of the amorphous regions during wetting alters the available hydrogen bonding sites within the polymer structure. When the fibre is dry, the polymer chains are closely aligned, and many hydroxyl groups are bound to each other, making them unavailable to water molecules. As the material absorbs water, these bonds are broken, creating more sites that remain open during the subsequent drying phase.
Testing Significance
Standardized testing of textile physical properties requires pre-conditioning the samples to a low moisture level before placing them in the standard testing atmosphere. This step ensures that all specimens approach equilibrium from the adsorption direction, which eliminates the variability caused by this lag.
Industrial Consequence
Failing to account for this difference can lead to errors in the calculated dry weight of bulk fiber shipments.