PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 5, Number 2, 2019
Enzymatic nanocellulose in papermaking – The key role as filler flocculant and strengthening agent, Ana F.Lourenço et al, Carbohydrate Polymers , 224, 115200. Nanocelluloses have been increasingly used in composites since their reduced size, high aspect ratio and stiffness confer great strength to the materials. In papermaking, it has been proved that harsh and expensive chemical pre-treatments to generate nanofibrils, such as TEMPO-mediated oxidation, are not the most favourable and therefore the use of cellulose microfibrils (CMF) have gained extra attention, especially those produced with the aid of enzymatic hydrolysis. In the present work, strategies to improve filler flocculation and the papermaking properties, by using enzymatic CMF, are provided. The CMF degree of polymerization was found to be directly related to precipitated calcium carbonate flocculation, leading to higher retentions in the fibre matrix. Besides, the paper dry and wet strengths were much improved, allowing in return the production of high-filler loaded handsheets with reduced requirements for common paper additives. The mechanism of alkyl ketene dimer (AKD) sizing on cellulose model films studied by sum frequency generation vibrational spectroscopy, Lei Li et al, Cellulose , 26 (5), pp.3415 – 3435 . Sum frequency generation vibrational spectroscopy (SFS) was employed to study the alkyl ketene dimer (AKD) sizing mechanism employed in the papermaking industry for hydrophobization of cellulose. The AKD was spun coat onto model cellulose films, which resulted in ≈ 2.6 nm thick AKD layers. The chain orientation of AKD molecules during the sizing process was measured at different temperatures. It was demonstrated that the chain orientation and conformation of AKD do not correlate with observed changes in sizing. The distribution of AKD molecules on model cellulose surfaces as a function of time and temperature was imaged via fluorescence microscopy to complement SFS measurements. It was concluded that the distribution of AKD plays a major role in the sizing effect. Environment-friendly packaging material: banana fiber/cowdung composite paperboard, M. Vishnuvarthanan et al, Environmental Chemistry Letters , 17 (3), pp.1429 – 1434. Wood is the main raw material for paper production, which in turn contributes to the decrease of forest resources. There is therefore a need of finding alternate sources for the production of paper. Here we prepared paperboard from the cowdung and banana fibers by chemical pulping. Banana fibers provide cellulose fibers, and lignin is removed. Pectin was added finely to the suspended pulp for binding fibers. Hydrogen peroxide was added to improve pulp brightness. The paper was tested for physical and mechanical properties. Results show that incorporation of cowdung increased the tensile and burst strength from 1 to 5 MPa and 10 to 50 kPa. The porosity was also decreased from 5 to 1 mL/min. The efficient water absorption (COBB) value was obtained for 50% of cowdung. The barrier properties such as oxygen transmission rate and water vapor transmission rate were gradually decreased to 1000 cc/m 2 day atm and 5 g/m 2 day. The antimicrobial properties of the prepared paperboard were tested against the Escherichia coli and Staphylococcus aureus , and it showed efficient activity against both the microorganisms. Investigation of the effect of para-amino benzoic acid (PABA) added starch-coated chemicals on the printability properties of paper, Arif Ozcan, Journal of Applied Biomaterials & Functional Materials , Jan-March 2019, pp.1-5. Paper is the most important material of the printing industry and is being improved due to the increasing needs of industry. The most important process to improve the optical and physical properties of paper is the surface coating. Paper has a smoother and opaquer surface with surface coating. In addition, brightness, whi teness, and yellowness values are improved
Technical Abstracts
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