ABSTRACT
Rheology is concerned with the description of the deformation of material under the influence of stresses. Polymer processing is not an art as looked upon by the entrepreneur; rather, it is the science of the flow and deformation of polymeric materials, namely, rheology. The advantage of fitting the rheological models to the unified curves lies in the fact that calculations involving pressure distributions, mold design, die design, heat transfer and so on are greatly simplified. Polyblending, modification of one polymer with another, involves the critical steps of selection of the component polymers, their appropriate grades, and their composition based on property requirements, as well as the proper choice of compounding method and conditions. A method for obtaining unified curves of normal stress difference versus shear rate as well as extensional viscosity versus shear rate is available. It has also been shown that dynamic viscoelastic data can also be coalesced in a similar manner.
