Predictive Geometrical Modeling of Crimp Interchange and Width Collapse during Wet Finishing
Geometrical modeling of crimp interchange predicts width collapse during wet finishing by balancing yarn swelling against mechanical jamming boundaries.
Yarn Swelling
Transverse Expansion
An increase in yarn diameter occurs when constituent fibres absorb liquid water or atmospheric moisture, expanding transversely across their longitudinal axes. The yarn swelling process modifies fabric density, reduces air permeability, and alters structural dimensions during wet finishing or end-use exposure. Hydrophilic fibres such as cotton and viscose exhibit high radial expansion upon liquid contact.
Laboratory instruments measure cross-sectional diameter changes using microscopic image analysis under controlled humidity steps.
Absorption Physics
Water molecules enter amorphous polymer regions, disrupting inter-chain hydrogen bonds and pushing polymer chains apart laterally. This micro-level molecular expansion accumulates across thousands of individual filaments within a yarn, producing measurable diameter increases. As yarn swelling proceeds, the enlarged thread cross-section fills interstitial voids within the woven or knitted matrix.
Increased yarn thickness increases crimp angles in crossing thread systems, causing macroscopic fabric contraction.
Pore Reduction
Volumetric expansion of yarn threads closes inter-thread pores, creating self-sealing barrier properties in tightly woven fabrics. Historical canvas constructions like Ventile utilize swelling behavior to block water penetration without applying synthetic chemical coatings. Synthetic hydrophobic fibres undergo minimal transverse expansion, maintaining constant pore dimensions when wet.
Application Impact
Quantifying thread expansion behavior guides the design of naturally water-resistant fabrics and breathable rainwear.