Swelling and dissolution of latex dispersions of the ethyl acrylate-methacrylic acid copolymers during alkalization

By using non-Newtonian viscometry and the static light-scattering method, changes in the structure of particles of latex dispersions of ethyl acrylate-methacrylic acid copolymer during alkalization with ammonium hydroxide were investigated. It was found that in dispersions with an acid content up to 20 wt% the particles only swell; at acid content between 20 and 40 wt% they decompose to smaller units represented by supermolecular aggregates of macromolecules, and only when approximately starting from 40 wt% of acid does the copolymer become molecularly dissolved. This means that even if dispersions with an acid content from c. 20 wt% are clarified by alkalization, no complete dissolution takes place.