Extensional flow behavior, macromolecules

Odell JA, Keller A, Mueller AJ (1989) Extensional flow behavior of macromolecules in solution. In Polymers in aqueous media, vol 223. Advances in Chonistry. American Chemical Society, Washington, pp 193—244. doi 10.1021/ba-1989-0223.ch011... 

We have illustrated the many ways in which elongational flow behavior can provide novel information about the behavior of macromolecules. Special emphasis has been given to rheological changes associated with extensional flow fields. 

There are significant differences in the behavior of polymeric fluids in these two types of deformation, and each type of deformation has a different effect on the orientation of macromolecules. For example, uniaxial and planar extensional flows impart significant molecular orientation in polymers during flow compared to shear flows. On the other hand, biaxial extensional flow is a weak flow and does not lead to a strong degree of molecular orientation. Furthermore, the rheological response can be significantly different for a polymer in extensional flow versus shear flow. We demonstrate these differences later in this chapter. 

---