Measurements of the shearhyphen;rate dependence of the intrinsic viscositylsqb;eegr;rsqb;were made on polystyrenes in several solvents, each of which differs in solvent power and solvent viscosity. Lowhyphen;shear capillary viscometers of the Maronndash;Belner type were used: shear stresses can be varied continuously from about 10 to a few tenths of a dyn/cm2, which is low enough to measure the zerohyphen;shear intrinsic viscositylsqb;eegr;rsqb;0. The effect of excluded volume on the behavior oflsqb;eegr;rsqb;thinsp;sol;thinsp;lsqb;eegr;rsqb;0hyphen;vshyphen;bgr;(the generalized shearhyphen;rate) curve was examined. The curves at and near the thgr; condition resemble that of Saitondash;Scheraga's prolate ellipsoid with axial ratiopthinsp;equals;thinsp;2, and those in good solvents resemble that ofpthinsp;equals;thinsp;3ellipsoid; the variation with solvent power is not so large as the theory of either Fixman or Chikahisa predicts. In the region of moderate to largebgr;, thelsqb;eegr;rsqb;thinsp;sol;thinsp;lsqb;eegr;rsqb;0hyphen;vshyphen;bgr;curve decreases continuously with increasingbgr;, as contrasted to the behavior of the ellipsoid, which levels off rather rapidly. The nonhyphen;Newtonian behavior is practically unaffected by solvent viscosity. In addition, the effect of polydipersity was discussed briefly.
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