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Wet-web strength increase by chitosan Makhlouf Laleg and Ivan I. Pikulik, Pulp and Paper Research Institute of Canada, Pointe Claire, Quebec, Canada - Keywords: Additives, Furnish, Wet webs, Wet strength, Dry strength, Chitin, Tensile strength, Rentention, Free- ness, pH. SUMMARY: Chitosan, an aminopolysaccharide obtained by hydrolysis of shellfish wastes, was evaluated as a wet- end additive in a laboratory study conducted with bleached kraft. Chitosan was found to increase the strength of never- dried wet webs, dry paper and rewetted paper. The

Compression behavior of press felts and wet webs Farouk El-Hosseiny, Albany International Research Co., Mansfield, Massachusetts, USA Keywords: Compression, Presses, Felts, Wet webs, Water removal, Paper machines. SUMMARY: Wet press felts were compressed at a high speed using a dynamic compressibility tester and at low speed using an Instron tester. At high speed speed, the liquid hydraulic pressure at the moving surface was meas- ured and its value subtracted from the total applied pres- sure in order to obtain the structural pressure carried only by

Special Issue: 9th INTERNATIONAL PAPER AND COATING CHEMISTRY SYMPOSIUM / INTERNATIONAL PAPER PHYSICS CONFERENCE Nordic Pulp & Paper Research Journal Vol 31 no (2) 2016 205 A new method showing the impact of pulp refining on fiber-fiber interactions in wet webs Jürgen Belle, Stephan Kleemann, Jürgen Odermatt, and Andrea Olbrich KEYWORDS: Initial wet web strength, Refining, dryness, Design of experiments, Scanning electron microscopy SUMMARY: There is still an on-going discussion about current theories regarding fiber-fiber bonds at dryness below 60

Nordic Pulp and Paper Research Journal Vol 21 no. 5/2006 653 KEYWORDS: polyelectrolytes, wet-web strength, tensile strength, shear tension, wet-web strength agents SUMMARY: In a wet web of paper at low solids content, the fibers are kept together by capillary forces due to the presence of free water between the fibers. The gradual removal of water results in deformation and collapse of the fibers and the strength of the wet web increases. But the swollen fibers cannot establish sufficiently close contact for interfiber molecular bon- ding to take place

PAPER PHYSICS Nordic Pulp & Paper Research Journal Vol 29 no (3) 2014 434 Improving the extensibility, wet web and dry strength of paper by addition of agar Alexey Vishtal and Elias Retulainen KEYWORDS: Extensibility, Spraying, Agar, Papermaking, Shrinkage, Film, 3D-forming SUMMARY: High extensibility of paper is of great importance for many finishing and converting operations. Extensibility is a key feature for the paper and paperboard which are utilized in production of advanced 3D-shapes. However, extensibility of the conventional paper and

The effects of TMP and filler stratifying on wet web runnability and end product quality of fine paper Antti Oksanen, Kristian Salminen, Jarmo Kouko, and Elias Retulainen KEYWORDS: Stratifying, Chemical pulp, TMP, PCC, Wet strength, Dry strength, runnability SUMMARY: Increase of filler content in paper improves quality of the final product and reduces raw material costs. However, this is often accompanied by deterioration of paper machine runnability. In this paper the effects of stratifying PCC (precipitated calcium carbonate) and TMP on fine paper

264 Nordic Pulp and Paper Research Journal Vol 23 no. 3/2008 KEYWORDS: Simulation, Wet webs, Network deformation, Poisson ratio SUMMARY: Triaxial deformations of very wet and weak fiber networks under tensile load were investigated by computer simu- lations. Numerical studies show that lateral Poisson’s ratio depends on the applied strain as shown by earlier micromechani- cal models. Simulations also capture experimentally observed behavior of network thickness during straining. Network thickness decreases or increases during stretching depending on the fiber

Strengthening of mechanical pulp webs by chitosan Markhloz~f Laleg and Zvan I. Pikzilik, Pulp and Paper Research Institute of Canada, Pointe Claire, Quebec, Canada Keywords: Ground wood, Handsheets, Chitin, Wet webs, Wet strength, Additives. SUMMARY: Handsheets were made from stone groundwood pulps (SGW) with several addition levels of chitosan and at several pH values. Chitosan was found to increase significantly the strength of never-dried webs, dry sheets and rewetted sheets, especially when introduced under neutral and alkaline conditions. The

516 Nordic Pulp and Paper Research Journal Vol 22 no. 4/2007 KEYWORDS: Simulation, Fiber networks, Wet webs, Paper Structure, Orientation SUMMARY: Tensile strength is used widely to characterize mechanical properties of paper. Recent numerical studies have revealed that wet tensile strength depends strongly on the num- ber of inter-fiber contacts. In this work, analytical models and computer simulations were utilized to examine the number of these contacts for pressed and stretched fiber networks. When the majority of fibers lie along the xy-plane, the analytical

200 Nordic Pulp and Paper Research Journal Vol 15 no. 3/2000 Keywords: Water permeability, Porosity, Darcy’s law, Gram- mage, Wet webs, Consolidation. SUMMARY: An apparatus for the measurement of the in-plane permeability of water-saturated fibre webs was built. A circular fibre web was compressed between two plain surfaces and water flowed radially through the compressed zone. The in-plane per- meability was measured as a function of total web porosity at two different grammages (30 g/m2 and 60 g/m2), with two different pulp types (softwood bleached kraft and