Low Liquor Jet Dyeing Heavy Cotton Duck Basics
Low liquor jet dyeing of heavy duck yields ten cent per metre savings but demands precise nozzle sizing and metered dosing to prevent unfixable rope creases.
Cellulose Hydration
Swelling Mechanism
Water adsorption into the amorphous regions of plant and regenerated fibres disrupts interchain hydrogen bonds, widening the interstitial spacing between microfibrils. This molecular expansion governed by cellulose hydration establishes the baseline physical dimensions and chemical receptivity of cotton, linen, viscose and lyocell during wet preparation. Unordered hydroxyl groups bind incoming water dipoles rapidly, which lowers the glass transition temperature of the polymer system.
Crystalline regions resist water entry completely. Processing liquor penetrates the expanded zones, converting compact dry fibre bundles into open, reactive matrices suitable for uniform chemical access.
Fibre Morphology
Lateral swelling increases yarn diameter while inducing axial shrinkage along the thread line. Lyocell undergoes rapid diameter increases under cellulose hydration due to its highly oriented crystalline network, creating intense internal stresses. Cotton displays lower swelling percentages because its natural spiral structure distributes expansion across concentric secondary wall layers.
The cross-sectional profile transitions from an indented kidney shape to an elliptical geometry in unmercerised cotton. Mercerisation with concentrated sodium hydroxide intensifies this swelling, converting cellulose I into cellulose II lattices permanently.
Processing Control
Aqueous pretreatments, scouring and dyeing stages require stable moisture levels to prevent uneven tension on continuous ranges. Inadequate cellulose hydration during the caustic impregnation phase produces patchy starch removal and pale resist spots in pigment printing. Swelling shifts the fluid hydrodynamic resistance within compressed fabric packages, changing pump delivery pressure inside yarn package dyeing machines.
Monitoring temperature controls swelling magnitude, as elevated thermal energy breaks water-cellulose bonds and reduces ultimate equilibrium uptake. Mill technicians measure differential pressure across circulation loops to detect improper volume changes.
Commercial Boundary
Fabric dimensional stability ceases to follow liquor uptake ratios once all available non-crystalline sorption sites reach saturation. Excessive cellulose hydration during wet rope transport accelerates mechanical creasing, thread distortion and fabric chafing. Regenerated filaments with high wet modulus resist cross-sectional deformation, whereas standard viscose loses more than forty percent of its dry tensile strength when wet.
Finishing lines apply synthetic resin crosslinkers to cap hydroxyl availability, thereby locking dimensional movement against subsequent domestic laundering cycles. Hydrophobic coatings or high synthetic blend percentages restrict this swelling mechanism entirely.