Spectroturbidimetric titration of polymer solutions

Abstract

AbstractA new modification of the method of turbidimetric titration based on taking the turbidity spectrum in the process of titration (accordingly designated “spectroturbidimetric titration” (STT)) has been proposed. STT permits the mass of the precipitated polymer Mγ to be determined in the process of titration with any change in the degree of dispersity of the precipitated polymer phase. The standardized plotting of the curve of solubility (CS) Mγ/(Mγ)max = f(γ), where γ is the volume ratio of the precipitator, proved to be independent of the nature of possible variation of the relative refractive index of the particles m = m (γ). STT was carried out with the commercial type of polystyrene (PS) (benzenemethanol) and withanionic poly‐α‐methylstyrene(P‐α‐MS) (cyclohexane‐octanol)in the serial turbidimeter FET. The turbidity was measured using five light filters at 4000–6000 Å. The speed of stirring was 64 rpm. Four rates of the precipitator input: W = 0.09, 0.20, 0.41, and 1.03 ml/min were used. Worse reproducibility of the colloid system structure in parallel experiments was found under low W correlated to the best division according to molecular weights. The STT method balanced these two antagonistic principles (like some others, though). Dependence on W of CS has been found. Graphic extrapolation of CS (with fixed Mγ% and W → 0) permitted the equilibrium CS to be determined. In a typical case three characteristic ranges of particles size changing in the process of titration were observed: decreasing (a reduction in gigantic fluctuations), a stable range, and increasing (particles coagulation). The colloid system structure may be regulated by selection of tiration conditions.