Melt Rheology An Overview

Understanding surface properties is important for dying and other textile finishing operations. 

FIGURE 10.4 Element undergoing shear deformation due to an applied force. 

Provided the deformation is uniform, the shear strain, y, is given by Equation 10.19 

The velocity gradient, or shear rate, y, is also very important in describing the response of a polymer to deformation. 

The viscosity, rj, is often described as the resistance of a material to flow the greater the viscosity, the greater the force needed to deform the fluid. That is, viscosity relates the measurable shear stress to the imposed shear rate (or visa versa). For Newtonian fluids, the viscosity is independent of shear rate and the stress may be written as follows  

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