PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 5, Number 2, 2019
filler retentions in the paper matrix. Moreover, the interactions between bleached pulp, CNF, mineral fillers and common paper additives, such as cationic starch, alkenyl succinic anhydride and cationic polyacrylamide, were investigated. The results allowed concluding that, depending on the materials applied, CNF are able to promote an adequate bonding between fibres and filler aggregates, reducing the requirements for the additives. The addition of carboxymethylated or TEMPO-oxidised CNF to the fibrous matrix led to handsheets with better structural, mechanical and optical properties than those of reference handsheets (without CNF and with additives). Bacterial nanocellulose in papermaking, Matej Skočaj, Cellulose , 26 (11), pp.6477 – 6488. Bacterial nanocellulose (BNC) is a unique natural nanomaterial that shares very few similarities with other natural or industrially produced nanomaterials. BNC can be produced by a variety of bacteria, as a survival aid in different ecological niches. BNC is traditionally produced by static or shaking culture methods, and the ‘mother vinegar’, or biofilm, is a typical example of this product after static vinegar fermentation. BNC has great potential in biomedicine, and recent studies have also demonstrated its use in the papermaking industry. It has nanoscale fiber size and large numbers of free hydroxyl groups, which ensure high inter-fiber hydrogen bonding. Thus, BNC has great potential as a reinforcing material, and is especially applicable for recycled paper and for paper made of nonwoody cellulose fiber. As well as enhancing the strength and durability of paper, modified BNC shows great potential for production of fire resistant and specialized papers. However, the biotechnological aspects of BNC need to be improved to minimize the cost of its production, and to thus make this process economically feasible. Isolation of lignocellulose nanofiber from recycled old corrugated container and its interaction with cationic starch – nanosilica combination to make paperboard, Seyed Mehdi Yousefhashemi et al, Cellulose , 26 (12), pp.7207 – 7221 . In recent years, many studies have been carried out on the use of cellulose nanofiber (CNF) produced from virgin fiber as a strengthening agent for improving the physical and mechanical properties of paper, while the use of CNF isolated from bleached virgin fiber is not necessary or reasonable for many recycled/impure products. In this due, novel lignocellulose nanofiber (LCNF) was produced from inexpensive recycled old corrugated container pulp by the ultra-fine grinding technique. The diameter of the resulted LCNF was in the range of 10 – 80 nm, while the cellulose crystallinity index and crystallite size reduced during the process to 49% and 4 nm, respectively. Regarding the chemical composition of LCNF, no significant change was observed in comparison to OCC fiber. But, an obstacle for the application of nanofibers, especially for paperboards, is dewatering problem. Accordingly, it was tried to evaluate the potential of cationic starch – anionic nanosilica combination as a drainage/retention aid to compensate for the negative effects of applying nanofibers in the pulp suspension, meanwhile the combination enhances the gains of LCNF application. The evaluation of pulp freeness showed that the addition of 3% nanofibers reduced dewatering ability about 100 ml CSF (around 33% loss). But, interaction of the nanosilica – starch system with the furnish containing LCNF not only compensated for the freeness reduction, but also caused a 32% or 57% increase in tensile index, in comparison to sample containing LCNF or control pulp respectively. Moreover, the addition of starch – nanosilica system with LCNF to pulp suspension, improved the retention of fine materials. Also, LCNF caused a reduction in thickness, bulk and bending resistance index of paperboard, while employment of the starch – nanosilica combination somehow off-set these negative effects. In addition, as a result of the cationic starch – anionic nanosilica system, the tear index was improved.
Technical Abstracts
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