Numerical Expression
Numerical expressions of the difference between absorption and desorption moisture levels quantify the stability of a fiber. The hysteresis ratio is calculated by dividing the moisture regain during the wetting phase by the moisture regain during the drying phase at a specific relative humidity. A value of one would indicate no difference between the two states, but most natural fibers yield a ratio between 0.7 and 0.9.
Internal Stress
Molecular friction within the fiber structure prevents the water molecules from leaving as easily as they entered. When the hysteresis ratio is low, it suggests that the fiber has a high degree of internal resistance or a very complex pore network. Wool typically shows a lower ratio than synthetic fibers because its protein structure undergoes more significant physical changes when wetted.
Shipment Stability
Warehouse managers use this ratio to understand how a fabric will react to the humidity cycles during ocean transit. If the hysteresis ratio of a cargo is known, the recipient can predict if the goods will stay heavy after being exposed to a damp environment. This helps in avoiding disputes over the weight of the goods when they arrive at the factory.
Comparative Metric
Standardized testing at sixty-five percent relative humidity provides a baseline for comparing different fiber types. The ratio varies depending on the previous processing history of the material, such as whether it was mercerized or heat-set. Measuring the hysteresis ratio is an effective way to check if a chemical treatment has successfully altered the moisture management properties of a textile.
