PAPER making! FROM THE PUBLISHERS OF PAPER TECHNOLOGY INTERNATIONAL ® Volume 10, Number 2, 2024
reaction mechanisms and working principles for achieving the required wet-strength is also analyzed. Moreover, a detailed comparative literature review of the physio-chemical properties of these wet-strength additives is also discussed. Finally, the paper also discusses the challenges associated with bio-based additives in improving the wet- strength of paper-based products, comparing the well-established synthetic wet-strength additives. PAPERMAKING “Surface Modification of Adsorbents for Removing Microstickies from Papermaking Whitewater”, Kunrui Xu, Wenxuan Mo, Fengshan Zhang, Carl J. Houtman, Jinquan Wan, & Bo Li, Ind. Eng. Chem. Res. , 63(17), 7950 – 7957 (2024). Adhesion and agglomeration of small sticky particles, i.e., microstickies, onto paper and paper machines cause serious problems for recycling mills. Because associations between materials with similar surface energies are strongest, we propose an “adhesives collect stickies” strategy to physically remove microstickies from whitewater systems. We characterized deposits from a commercial paper machine and observed a large amount of acrylate-based materials. Based on this observation, we chose to graft glycidyl methacrylate (GMA) to surfaces of polypropylene (PP) to make it more similar to the deposited stickies, which will encourage association by van der Waals forces and interdiffusion. The modified material efficiently collected acrylic adhesive particles suspended in water (58.3%) and particles found in paper mill whitewater (40.6%). Additionally, a flow cell incorporating layers of modified mats of fibers shows good efficiency (40.6 – 49.4%) for collecting stickies at steady flow rates. This strategy may provide a method for removing microstickies without disturbing the chemical environment of the papermaking system. PULP “Flax biorefining for paper production”, L. Verónica Cabañas-Romero, Oriol Cusola, Carolina Buruaga-Ramiro, Cristina Valls, M. Blanca Roncero & Susana V. Valenzuela, Cellulose , Vol.31, 4497 – 4508, (2024). In this work, we assessed the potential of Cel6D, a recently reported exocellulase from Paenibacillus barcinonensis, as a biorefining agent for flax pulp. Pulp fibers were treated with this enzyme, Cel9B (an endocellulase previously shown to possess biorefining action) and the two in combination. Samples of biorefined flax pulp were mechanically refined to obtain handsheets. All three biorefining treatments decreased air permeance in the handsheets. Cel9B increased tensile index and folding endurance, and the Cel6D − Cel9B combination increased tensile index and burst index but also resulted in markedly decreased tear index and folding endurance. On the other hand, Cel6D increased tensile index and burst index; also, more importantly, it increased tear resistance, albeit slightly, relative to the other two treatments. The results of this work can be useful to understand the differential effects of exocellulases and endocellulases as biorefining tools and open up new avenues for exploring their use in other biotechnological applications. TESTING “Optical measurement of paper moisture content with application in paper pressing”, Hooman Mahdavi, Boris Stoeber & Sheldon Green, Cellulose , Vol.31, 2557 – 2570, (2024). We present a novel non-contact method for measuring the moisture content of paper. In the method, paper is illuminated obliquely by light from an IR LED, and the light reflected from the paper is imaged by a short-wave infrared (SWIR) camera. Owing to the high absorptivity of liquid water to light in the 1400 – 1500nm wavelength range, the intensity of light reflected off the paper diminishes sharply with increasing moisture content. We show that for a variety of paper samples (Whatman paper, NBSK,
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Technical Abstracts
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