Structural Transition
Polymorphic restructuring changes the spatial orientation of glucan chains inside plant cell walls from parallel to antiparallel alignment. Caustic mercerization drives cellulose phase transformation when sodium hydroxide penetrates crystalline microfibrils. This molecular rearrangement permanently alters the physical properties of cotton yarns.
Swelling Mechanism
Penetration of hydrated sodium ions into native fiber walls cleaves intermolecular hydrogen bonds holding together the cellulose I lattice. As the crystal structure expands, sodacellulose intermediate complexes form prior to washing and neutralization steps. Complete cellulose phase transformation requires sufficient swelling pressure to convert tightly packed parallel chains into lower-energy antiparallel cellulose II structures.
Inadequate alkali concentration or low bath temperatures prevent full conversion, leaving untransformed cores that cause uneven physical shrinkage.
Tensile Modification
Internal stress redistribution during lattice conversion enhances overall single-strand yarn tenacity while increasing elongation at break. Higher extent of cellulose phase transformation improves fiber roundness, smoothing the yarn surface to increase specular luster. Woven goods exhibit enhanced tear strength following uniform molecular restructuring in caustic baths.
Conversion Limit
Analytical diffraction methods measure the extent of crystalline phase change after thorough rinsing eliminates residual alkalis. The cellulose phase transformation reaches saturation when all accessible native microfibrils convert, beyond which additional alkali exposure causes chemical degradation rather than further structural improvement.
