The effect of Fenton chemistry on the properties of microfibrillated cellulose

A fully bleached birch kraft pulp was treated with acidic hydrogen peroxide in the presence of ferrous ions (Fenton's reagent) and thereafter treated mechanically in a colloid mill to produce a product containing microfibrillated cellulose (MFC). The produced MFC products were chemically and morphologically characterized and compared with MFC products produced without pretreatment as well as with enzymatic hydrolysis. Fenton treatment resulted in an increase in total charge and number of carbonyl groups while the intrinsic viscosity decreased. The Fenton treated pulps were easier to process mechanically i.e. they reached a higher specific surface area at a given mechanical treatment time and the MFC produced had a stable water-fibre suspension for at least 8 weeks compared to enzymatic pretreated pulps and pulps not subjected to any pretreatment. © 2014 Springer Science+Business Media Dordrecht.CODEN: CELLE</p

Chemical pulping: the influence of xylan on the sensitivity towards fiber damage, xylan added in the oxygen stage

The aim of this study was to investigate if extra xylan added during oxygen delignification of kraft spruce fibers could contribute to reduce the effect of fiber damage introduced during the cook. Two pulps were produced, one with and one without mechanical treatment at the end of the cook. The pulp produced without mechanical treatment was oxygen delignified with xylan added in the oxygen stage. The pulp produced with mechanical treatment was oxygen delignified both with and without xylan added. Results did not indicate that xylan added in the oxygen stage could repair the already introduced fiber damage. Added xylan had a fiber straightening effect as seen earlier when xylan was added in the cook. Xylan added in the oxygen stage resulted in improved tensile strength development. However, the negative effect from introduced mechanical treatment still influenced the strength properties more than could be compensated by the added xylan. SEM-images could not identify any differences between the investigated pulps. It seems likely that the birch xylan added forms a uniform but nonhomogeneous coating on the fiber surfaces. Possibly the xylan has penetrated into the fiber wall to a greater extent compared to previous studies when xylan was added in the coo