Determination of time for blank solution of ammonium polyphosphates to flow through the capillary in Ubbelohde viscometer

摘要

While polymer solution flows through the capillary of Ubbelohde viscometer,adsorption of polymer to the surface, sometimes, seriously change the physical and chemical nature of the surface. The effective diameter is narrowed. Thus, the time for blank solution to flow through the capillary is different before and after measuring time of the solution of varied concentration, making the average molecular weight strikingly different. Despite the importance of the time for blank solution, no uniformly adopted method has been established to determine it. However, for the currently used methods , η sp/c is no longer the linear function of c (g/100ml) as the concentration decreases. In this paper, solution of a wide range of low concentration is prepared (5.0×10 -4 ～5.0×10 -3 g/ml), and the addition of electrolyte is considered. A new method to determine the time for blank solution is proposed. Experimental data and theoretical analysis show that this method is more applicable and accurate, making η sp/c the linear function of c(g/100ml) at wider range of low concentration.