Potentiometric titration of carboxy groups close to the surface of irradiated fluoropolymers

Carboxy groups on fluoropolymers can be generated by electron beam irradiation of these in the presence of oxygen. Their concentration can be measured using potentiometric titration. The use of different aqueous mixtures of dispersing agents was studied, because of the bad wettability properties of the irradiated fluoropolymer powders. The dispersion quality was controlled by particle size analysis. The mixture of 50 vol-% ethanol and 50 vol-% water was found to be suitable. The principal advantages of this mixture compared to the frequently used N,N-dimethylacetamide solution consist in the short-time experimentation and in the lower and stable blank readings despite the long storage times.