Investigation of the Adsorption Behavior of Jet-Cooked Cationic Starches on Pulp Fibers

The optimization of the thermal treatment of cationic starch in the paper industry offers the opportunity to reduce the energy consumption of this process. Four different industrially relevant cationic starches, varying in source, cationization method and degree of substitution were treated by a steam-jet cooking procedure, comparable to industrially employed starch cooking processes. The influence of the starch properties and cooking parameters on the adsorption behavior of the starches on cellulosic pulp was investigated. The adsorbed amount was affected by the cooking temperature and the type of starch. For some starch grades, a cooking temperature of 115 °C can be employed to achieve sufficient starch retention on the pulp fibers. The energy consumption could further be reduced by cooking at higher starch concentrations without loss of adsorption efficiency.

Short-term steam treatment of MFC gel with and without water-soluble cellulose derivative

Microfibrillated cellulose (MFC) with and without added CMC was exposed to short-term dynamic thermal treatment using a steam jet cooker. The effects of the elevated temperature (130 °C, ∼3 bar) and shear forces on the rheology, crystallinity index, UV/VIS adsorption and water retention were measured. Jet cooking increased the viscosity and gel strength of the MFC and MFC/CMC mixture but with CMC alone a slight decrease in viscosity was observed. The water retention capacity and crystalline indices of the MFC were not greatly affected by the short-term thermal treatment and shear forces, although a slight increase in the UV/VIS absorbance was observed.