Showing papers by "Tom Lindström published in 1996"
TL;DR: In this article, the effects of microparticulate dual retention aid systems with those of classical dual polyelectrolyte systems on retention, flocculation, reversibility and dewatering were investigated.
Abstract: The aim of this investigation was to compare certain features of microparticulate dual retention aid systems with those of classical dual polyelectrolyte systems. In particular the flocculation behaviour of a papermaking stock after dispersion was investigated. A BDDJ-method was developed to characterize the reversibility of flocculation. The effects of monocomponent polymer systems (various cationic polyacrylamides, cationic starch and a cationic condensation resin), a classical dual system (cationic starch/A-PAM) and various microparticulate systems SiO,, AI, in combination with C-starch and Na' montmorillonite in combination with C-PAM) on retention, flocculation, reversibility and dewatering were investigated. In general, an increase in retention level leads to a greater dewatering. In the systems investigated, powerful retention aids generally show a reversible flocculation behaviour together with a high retention capacity. In dual systems, a high reversibility was found to be a prerequisite for good dewatering. Microparticle systems generally show a reversible flocculation pattern, whereas classical dual systems are both less reversible in their flocculation behaviour and show a lower dewatering in spite of high retention levels. Thus, the known superiority of microparticulate systems in bringing about good dewatering is well demonstrated and may be partly understood from their reversible flocculation behaviour.
22 citations