MODIFIED STARCHES FOR INCREASING PAPER STRENGTH

The effect of the chemical composition and molecular weight of modifie d starches on the properties of kraft pulp and handsheets was examined . Conventional Cationic starches increased pulp freeness, retention, a nd dry strength of paper, but reduced the strength of never-dried wet webs. Cationic starches which contained aldehyde groups similarly incr eased freeness, retention and dry strength, but also increased the wet -web strength of both never-dried and dried-and-rewetted sheets. This strengthening effect results from the formation of hemiacetal bonds be tween the starch and the cellulose fibres.