Viscous Behaviour
Non-Newtonian fluids exhibit a decrease in viscosity when subjected to mechanical stress or high flow rates. This phenomenon of rheological shear-thinning is necessary for the formulation of starch and polymer sizing agents applied to linen warp yarns. At rest, the sizing paste remains thick and cohesive, but it flows easily when squeezed under the pressure rollers of the sizing machine.
This behavior ensures that the liquid distributes evenly across the yarn surface before setting into a protective coating.
Application Efficiency
High speed weaving looms place immense mechanical strain on warp yarns as they are rapidly lifted and lowered. The presence of rheological shear-thinning allows the sizing agent to penetrate the core of the yarn bundle during high pressure application while remaining on the surface as a protective film once the pressure is released. This dual action reduces yarn hairiness and increases abrasion resistance on the loom.
The resulting yarn runs smoothly through the heald eyes without shedding excessive sizing dust.
Performance Limit
Sizing kitchens must monitor mix temperatures since extreme heat alters fluid behavior. If the mixture degrades, this rheological shear-thinning property fails to prevent warp breakages. The technical parameters are recorded on the sizing log sheet.
