Interface behavior of quaternized chitosan on cellulosic substrates

Quaternized chitosan (QCS) was prepared and its interface behavior on cellulosic substrates was investigated. FT-IR result indicated that quaternary ammonium groups were connected to -NH₂ in chitosan, and the highest degree of substitution (DS) of QCS was 80.0 %. The adsorption behavior of QCS was well performed on cellulosic substrates. The initial critical concentrations of QCS were between 10 mg/l and 20 mg/l, which were related to its DS and the weight average molecular weight (M _w ): the critical concentration decreased with the increasing DS of QCS, and the concentration increased when M _w increased. The results from SEM and particle size revealed that the flocculation took place mainly because the electrostatic interaction between cellulosic substrates and QCS, which can be accelerated by forming a charge patch. At last, QCS displayed high efficiency as a retention and drainage-aid agent through a Schopper-Riegler beating degrees tester.