Viscosity and Normal Stress Differences

Chapter
Part of the Engineering Materials and Processes book series (EMP)

Abstract

Viscosity is the property most used with molten plastics. It relates the shear stress to the shear rate in steady simple shear flow, which is the deformation generated between two parallel plates, one of which undergoes linear displacement. For viscoelastic fluids, two other quantities are needed for a complete description of the stress field, and these are the first and second normal stress differences. The viscosity and the two normal stress differences are functions of shear rate that are called the viscometric functions, and flows governed by these are called viscometric flow s. In addition to simple shear, other viscometric flows include flow in straight channels and rotational flows between concentric cylinders, between a cone and plate and between two disks. Flow in an extruder is dominated by the viscometric functions, mainly the viscosity. This chapter describes the dependence of viscosity on shear rate, temperature, molecular weight and its distribution, tacticity, comonomer content, and long-chain branching.

Keywords

Shear Rate Molecular Weight Distribution Complex Viscosity Shift Factor Normal Stress Difference 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  1. 1.MontrealCanada
  2. 2.FreeportUSA

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