The rheological properties of partially hydrolyzed polyacrylamide(PHP) aqueous solutions at low shear rates have been studied by using a concentric cylinder rotational rheometer. Some rheological parameters: non Newtonian index( n ), consistency coefficient( K ), apparent viscosity( η a) and yield stress( τ y) have been determined at conditions of different PHP concentration, temperature and salinity. The results showed that at shear rates of 1～5 s -1 a yield stress occurred, PHP aqueous solution behaved as a Bingham fluid and a linear relationship between τ y and PHP concentration( c ) was obtained: τ y= kc .
The azo chromophore anchored polyurethanes were synthesized by azo coupling of 4 nitrobenzenediazonium tetrafluoroborate and reacting the obtained 6 nitrobenzothiazole 2 diazoniun tetrafluoroborate with polyurethane in dimethylforamide in the presence of HAc and its sodium salt. The polyurethanes were characterized by IR, UV Vis and 1H NMR spectra. The method has the advantages of simplicity and facility in preparing polyurethane NLO materials with different chromophores.
