ADSORPTION OF CATIONIC STARCH ON EUCALYPT PULP FIBERS AND FINES

Cationic starch is extensively used in papermaking to increase paper s trength and improve first pass retention. Starch, a high molar mass po lymer of glucose, is commercially extracted from a number of plant sou rces including corn, wheat, potato and tapioca. In their natural state , starch polymers are generally uncharged (i.e. electrically neutral) and are only weakly adsorbed by fibres. The cationization process, in which the starch polymers are chemically modified by substituting posi tively charged (i.e. cationic) chemical groups into polymer, was devel oped during the 1950s (1). This led to a substantial improvement in th e efficiency of starch utilization, as cationic starch is able to chem ically bond through electrostatic attraction to fibres and fines which are negatively charged (i.e, anionic) (1).