The Rousendash;Zimm theories of polymer solution dynamics have been extended to include normal stresses as well as shear stresses and have been evaluated for lowhyphen;amplitude oscillatory shear. Two normal stress coefficients (zgr;d, characterizing a displacement function, andzgr;*, characterizing the oscillation about the displacement) appear as analogs to the complex viscosityeegr;*for shear stress. Theoretical predictions are compared with data obtained with a Weissenberg rheogoniometer on five dilute solutions of monodisperse polystyrene (Mthinsp;equals;thinsp;1.8thinsp;times;thinsp;106and4.1thinsp;times;thinsp;105) in Aroclor 1254. The models are found to describe the measuredeegr;*andzgr;dwith equal good success, but uncertainties inzgr;*measurements preclude complete verification. Strong evidence is presented to support the modelhyphen;independent prediction thatohgr;zgr;dthinsp;equals;thinsp;eegr;Prime;.
展开▼
