Reconciling Mass Balance Variances in Industrial Alkaline Scouring of Hackled Flax Roving
Standardizing dry mass calculations and auditing liquor COD reconciles industrial scouring loss variances between raw hackled flax and finished packages.
Sodium Hydroxide Bath
Chemical Solution
Industrial wet processing of bast fibers uses a highly alkaline aqueous medium to extract non-cellulosic materials and swell the crystalline fiber structure. This reactive solution is the sodium hydroxide bath, which is used during roving scouring and mercerization. The concentration of the solution determines the degree of pectin removal and cell wall swelling.
It forms the reactive environment for most heavy chemical finishing treatments in the linen mill.
Mercerization Process
Concentrated alkaline solutions alter the physical structure of cotton and linen fibers by converting cellulose I to cellulose II. This swelling reaction occurs when the yarn passes through a cold sodium hydroxide bath at a concentration of over two hundred grams per liter. The treatment rounds the fiber cross-section, increasing the surface luster and the affinity of the yarn for reactive dyes.
Tension is applied during the process to prevent the yarn from shrinking, which maximizes the tensile strength of the fiber. The result is a stronger yarn with a smooth, glossy surface.
Neutralization Cycle
Acidic rinsing must follow the alkaline treatment to stop the chemical reaction and prevent structural damage to the cellulosic fibers. The carryover from the sodium hydroxide bath is neutralized using a dilute solution of acetic acid or sulfuric acid. This neutralizing step is critical because residual alkalinity would cause the fibers to degrade during drying and subsequent weaving.
The process completes the alkaline treatment cycle.