Quantifying Anti Friction Lubricant Protection Limits for Elastane Cores under High Drag Jet Processing
Sustaining a 1.8 percent ester lubricant film on elastane cores prevents elastomeric rupture when jet nozzle pressure exceeds 2.2 bar.
Fluid Shear
Flow Velocity
Velocity gradient within a moving liquid represents the fundamental physical force that drives the dispersion of dyes and the penetration of finishing chemicals into textile substrates. During continuous dyeing, fluid shear helps break up pigment agglomerates to ensure a uniform color. This force is particularly high when liquid is forced through narrow nozzles or padding nips.
Sizing Application
Warp sizing baths apply starch solutions to yarns at high speed to prepare them for weaving. The action of fluid shear in the sizing box determines the degree of penetration into the yarn bundle versus the amount of surface coating. Balancing these factors ensures that the yarn has both internal strength and a smooth surface.
Viscosity Effects
Thickeners used in textile printing pastes must be sensitive to the mechanical forces of application. Under high fluid shear, the print paste must flow easily through the screen mesh, but it must thicken immediately upon contact with the fabric. This behavior ensures clean print lines and prevents the design from spreading.
Equipment Design
Dye kitchen mixers and homogenizers are designed to generate controlled levels of turbulence. To dissolve difficult dyestuffs, the mixer must produce sufficient fluid shear to break up the granules without degrading the polymer chains of the thickener. Excessively high shear can permanently reduce the viscosity of the paste, leading to paste runniness during printing.