Rheological Behavior of Molten Polymers with Solubilized Gaseous Component

Rheological Behavior of Molten Polymers with Solubilized Gaseous Component 

Similarly, when using a plunger-type capillary rheometer, as discussed in Chapter 5, the rheometer must be attached with a high-pressure chamber, so that at the die exit the polymer melt with solubilized gaseous component can exceed the critical pressure 

Another method is to use continuous-flow capillary (or slit) rheometry, as discussed in Chapter 5. Han and coworkers (Han and Ma 1983a, 1983b Han and Villamizar 1978 Han et al. 1976) were the first to use a continuous-flow capillary (or slit) rheometer to determine the viscosity of polymer melts with solubilized gaseous components. Later, other investigators (Elkovitch et al. 1999 Lee et al. 1999 Royer et al. 2000, 2001) employed the same method. 

Using the cylindrical coordinate system (r, 6,z) we can describe the r-component of stress (r, z) in the capillary and reservoir sections by 

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