Mercerization Index
Chemical evaluation of cotton fibres measures the effectiveness of the mercerization process through preferential absorption of barium hydroxide. Technicians calculate the barium activity number by comparing the absorption capacity of a mercerized sample against an unmercerized control. This ratio indicates the permanent swelling of the cellulose structure.
Chemical Mechanism
Testing involves soaking weighed portions of treated and untreated cotton in a standard solution of barium hydroxide for a specific duration. After the immersion, the operator titrates the remaining solution with hydrochloric acid to determine the amount of alkali absorbed by each sample. A barium activity number of 100 represents no change, while values between 135 and 150 signify a thorough commercial mercerization.
High readings confirm that the fabric will exhibit improved lustre and dye affinity.
Calculation Method
Internal morphology changes when the cotton hair collapses from a flat ribbon into a cylindrical shape during the caustic treatment. The resulting barium activity number functions to verify that the caustic concentration and temperature were optimal for the specific fabric construction.
Process Control
Finished goods inspections rely on this metric to ensure consistency across different dye lots. Variation in the barium activity number causes visible differences in shade depth even when using the same dye recipe.
