Latex–fiber interaction and paper reinforcement

A model system for studying the reinforcement of paper is provided by the use of cationic latexes. The control of pH during addition of the latex to the pulp determines the uniformity of the latex deposition on the fibers. It is demonstrated, using scanning electron microscopy and mechanical testing of the sheet, that the dry and wet strength properties are improved by the more uniform distribution of a film-forming latex. Conversely, a nonfilming latex impedes bonding to the extent that the fiber surface is covered.