Definitions and Implications:Shear

Definitions and Implications:Shear Stress - Force/unit area or pressure applied to deform the rubberHigh shear stress and low particle to particle attraction increase the rate of dispersion Maximum shear stress occurs in the nip, between the helix & chamber and is highest at the highest viscosityShear Strain - Measure of deformation that rubber undergoesShear strain occurs behind the rotor helix and results in deformation and distributive mixingShear Rate - Rate at which the deformation takes placeViscosity - Measure of resistance of rubber to deform under applied stressViscosity changes significantly with temperature. An increase of 20 C can halve the viscosity. Since shear stress is lower at lower viscosities, dispersive mixing is slower at higher temperatures.