Optical heterogeneities of poly(acid)amide concentrates

Abstract The method of turbidity spectra has been used to determine the micron-size heterogeneities present in the prepolymer solutions used to synthesize polyimides (poly-(4,4-hydroxydiphenylene) pyromellitamides) produced by polycondensing the respective monomers in dimethyl fornamide. The proportion by volume of the heterogeneities present in the reaction solutions has been established to consist of admixtures entering with the monomers, and of polymer particles forming by secondary reactions during the polycondensation. The numbers of the heterogeneities per unit of volume and their average radius depend on the varying polycondensation conditions. The most significant and potential source of the heterogeneities is assumed to be the heterogenous distribution of the solid monomer in the space (bulk) of the reaction mixture.