Softening Process
Polymer physics defines the temporary reduction in glass transition temperature that occurs when water molecules penetrate the amorphous regions of cellulose fibres. This structural change, known as moisture plasticization, increases the mobility of the cellulose chains and softens the natural gums in flax. Spinning mills rely on this effect to make the stiff flax fibres pliable before drafting.
The softening remains a critical prerequisite for high-speed wet spinning operations. In laboratory testing, the elasticity of the plasticized fiber increases up to threefold compared to its bone-dry state, representing a dramatic shift in mechanical response.
Drafting Action
Hot water in the spinning bath accelerates the moisture plasticization by breaking the intermolecular hydrogen bonds within the flax fiber bundle. This allows the individual ultimate fibres to slide smoothly past each other under the influence of the draft rollers. Without this lubrication, the stiff fibers would break, causing frequent yarn defects.
Strength Recovery
The yarn regains its natural stiffness as the water evaporates after winding. This transition stabilizes the twist inserted during spinning, lock-in the yarn structure and improving its tensile strength. Controlled drying ensures that the plasticization is fully reversed before the yarn reaches the fabric production stage.
