Method for evaluating the solubility of a crystalline substance in a polymer

Abstract

A method for evaluating the solubility of a crystalline substance in a polymer comprises a) providing at least one sample of an intimate crystalline substance/polymer mixture at a predetermined crystalline substance concentration; b) annealing the sample at a constant temperature Ta for a period of time; c) heating the annealed sample while recording the heat flux over time by DSC; d) identifying a DSC dissolution endotherm in the recorded heat flux, if any; e) considering the crystalline substance concentration as a concentration above the crystalline substance solubility in the polymer at temperature Ta when there is a DSC dissolution endotherm identified, and considering the crystalline substance concentration as a concentration less than or equal to the crystalline substance solubility in the polymer at temperature Ta when there is no DSC dissolution endotherm identified. Thus, the method yields the upper and lower bounds for the equilibrium solubility at a given temperature or the upper and lower bounds for the equilibrium solubility temperature at a given crystalline substance concentration. The method improves accuracy of measurement near the glass transition temperature.

Dependencies are inferred from the claim text.