Study on the rheological properties of fast-growing eucalyptus

To study the effect of retention and drainage aids on the fast-growing eucalyptus bleached kraft pulp (EBKP) suspensions, different concentrations of cationic polyacrylamide (CPAM) and cationic starch were dosed with EBKP suspensions and their effects on rheological properties were studied. The shear yield stress (τy) of softwood bleached kraft pulp (SBKP) and poplar alkaline peroxide mechanical pulp (PAPMP) were compared and evaluated for their potential applications. The results show that in the steady-state shear condition, the τy of EBKP is proportional to the pulp mass concentration (Cm), corresponding to the exponential relation . SBKP had the highest τy values, followed by EBKP and PAPMP. Adding CPAM and cationic starch to EBKP suspensions at low to moderate doses increased the τy, but once the levels reached a certain point, the τy values began to deteriorate. This research is crucial to achieve optimally and stabilize the downstream manufacturing process in papermaking.

Impact of cationic polyacrylamide for a new kind of pulp ultrasonic wheat straw on alkyl ketene dimer sizing

As a new kind of pulp that can protect the environment by conserving wood resources, ultrasonic wheat straw pulp has received increasing attention. It is prepared by the mechanical effect of ultrasound, the effect of cavitation, and thermal effect, and it does not require a large amount of chemical additives. Different pulp methods yield differences in performance. The conventional method of sizing is difficult to achieve the ideal of wheat straw pulp ultrasonic sizing effect. This work examined the effects of additives and surface charge on sizing by studying ultrasonic wheat straw pulp with 0.25% alkyl ketene dimer (AKD) added in the form of
a commercial emulsion without separate retention aids. As a retention aid cationic polyacrylamide (CPAM) contents were prepared and added to fiber suspensions at the wet end of the papermaking process. The relationship between CPAM and the zeta potential of papermaking furnish and sizing degree, the strength properties of the paper sheet, and the factors that affected measuring the zeta potential were investigated. As the CPAM content increased, the surface morphology, the zeta potential and the strength properties of the paper sheet presents a curve.