FLOW BIREFRINGENCE OF DILUTE-SOLUTIONS OF POLYETHYLENEOXIDE OF HIGH MOLECULAR-WEIGHT AT HIGH-RATES

Birefringence and orientation angle of solutions of Polyox WSR 301 in the concentration range of 50 to 1350 ppm have been measured up to 8000 s-1. A few marked differences with ordinary flexible polymers have been evidenced: (i) a very low value of the extinction angle at high shear rate, which could be attributed to an unusually high molecular weight; (ii) the independence of this angle on the concentration, which is due to the variation of the flexibility with the concentration, as shown by the study of the concentration dependence of the segmental optical anisotropy; (iii) the concentration dependence of the elongation shows a plateau value for c ≳ 150 ppm, which may come from a concentration dependent and reversible association process, as shown from reduced viscosity measurements. © 1979 Dr. Dietrich Steinkopff Verlag.