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Contents
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Volume 23, 2008, Issue No. 4
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A method for the measurement of thermal contact diffusivity of paper coating structures
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Philip Gerstner, Jouni Paltakari and Patrick A.C. Gane*, Helsinki University of Technology, Espoo, Finland, *also Omya Development AG, Oftringen, Switzerland
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Abstract:
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A method to study thermal diffusivity by the measurement of temperature responses through porous tablets of pigmented coatings at different binder concentrations is described and discussed. Measurements of the internal temperature distributions suggested that there was a gradient of thermal diffusivity in the pigment tablets which was due to the tablet forming technique.
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Issue:
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Volume 23, 2008, Issue No. 4
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Pages:
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354-362
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Online Date:
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December 15, 2008
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DOI:
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10.3183/NPPRJ-2008-23-04-p354-362
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Keywords:
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Electrophotography, Heat diffusion, Heat set offset, Heat transfer, Mottling, Paper coatings, Porous material, Thermal effects, Thermal properties, Toner fusing
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Increasing accessibility and reactivity of paper grade pulp by enzymatic treatment for use as dissolving pulp
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Viviana Köpcke, David Ibarra and Monica Ek, Royal Institute of Technology, KTH, Stockholm, Sweden
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Abstract:
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The feasibility of using different kraft pulps (bleached hardwood kraft pulps from eucalypt and birch) as dissolving pulps for the viscose process was investigated. The pulps were subjected to several enzymatic and chemical pretreatments in order to improve the accessibility and reactivity of the pulps and to reduce the hemicellulose content.
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Issue:
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Volume 23, 2008, Issue No. 4
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Pages:
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363-368
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Online Date:
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December 15, 2008
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DOI:
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10.3183/NPPRJ-2008-23-04-p363-368
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Keywords:
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Alkali extraction, Dissolving pulps, Hardwood, Kraft pulp, Monocomponent endoglucanase, Reactivity, Xylanases
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Correlation of fiber shape measures with dilute suspension properties
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Emilio J. Tozzi and Daniel J. Klingenberg, University of Wisconsin, Madison, Wisconsin, USA, C. Tim Scott, USDA Forest Products Laboratory, Madison, Wisconsin, USA
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Abstract:
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Correlations between the intrinsic viscosity of fiber suspensions and different measures of fiber shape were investigated.
The intrinsic viscosities of suspensions of fibers with various shapes and aspect ratios were determined numerically. The shape measure that correlated most strongly with intrinsic viscosity was an invariant of the hydrodynamic resistance tensor related to the hydrodynamic drag coefficients on a fiber. This measure can be computed from 3D images of real fibers, and could potentially be a useful quantity for describing fiber shape.
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Issue:
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Volume 23, 2008, Issue No. 4
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Pages:
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369-373
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Online Date:
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December 15, 2008
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DOI:
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10.3183/NPPRJ-2008-23-04-p369-373
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Keywords:
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Fiber shape, Intrinsic viscosity, Shape measure, Simulation
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Registration and point wise correlation of local paper properties
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Ulrich Hirn, Markus Lechthaler and Wolfgang Bauer, Graz University of Technology, Austria
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Abstract:
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A systematic procedure to combine 2D paper property maps from different measurement sources using image registration is presented. The proposed method integrates arbitrary resolution 2D paper measurement data into composite datasets. It was demonstrated that such datasets can be used to model local variations of print density from multiple local paper properties.
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Issue:
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Volume 23, 2008, Issue No. 4
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Pages:
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374-381
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Online Date:
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December 15, 2008
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DOI:
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10.3183/NPPRJ-2008-23-04-p374-381
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Keywords:
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Calendering, Compressibility, Formation, Image registration, Paper property maps, Print mottle
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Mechanism of paper strength development by the addition of dry strength resin and its distribution within and around a fiber wall - Effect of application method
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Ichiro Mihara, Takushi Sakaemura and Tatsuo Yamauchi, Kyoto University, Kyoto, Japan
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Abstract:
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Fundamental mechanical and optical properties of papers were considered in a comprehensive study of the relation of the mechanism of strength development to the method of addition of polyacrylamide dry strength resin (PAM).
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Volume 23, 2008, Issue No. 4
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Pages:
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382-388
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Online Date:
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December 15, 2008
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DOI:
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10.3183/NPPRJ-2008-23-04-p382-388
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Keywords:
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Application method, Dry strength agents, Handsheet properties, Polyacrylamide, Tensile strength
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Dewatering mechanisms and their influence on suction box dewatering processes – A literature review
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Peter Åslund and Hannes Vomhoff, STFI-Packforsk AB, Sweden
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Abstract:
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This review summarizes the present knowledge of suction box dewatering mechanisms. Three mechanisms that determine the dry content of the web after dewatering are identified, viz. web compression, displacement of water by air, and rewetting. However, direct measurements are required to better understand the suction box dewatering.
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Issue:
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Volume 23, 2008, Issue No. 4
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Pages:
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389-397
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Online Date:
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December 15, 2008
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DOI:
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10.3183/NPPRJ-2008-23-04-p389-397
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Keywords:
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Compression, Displacement, Rewetting, Suction box, Vacuum, Water removal
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Method for studying the deformation of a fibre web during a suction pulse
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Peter Åslund and Hannes Vomhoff, STFI-Packforsk AB, Sweden
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Abstract:
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This article describes a laboratory suction box that was built to study the dynamic thickness deformation of a fibre web during a suction pulse. The measurements were used to study the dewatering mechanisms at suction box dewatering.
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Issue:
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Volume 23, 2008, Issue No. 4
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Pages:
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398-402
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Online Date:
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December 15, 2008
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DOI:
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10.3183/NPPRJ-2008-23-04-p398-402
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Keywords:
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Compression, Displacement, Laboratory Apparatus, Rewetting, Suction box, Vacuum, Water removal
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The deformation of chemical and mechanical pulp webs during suction box dewatering
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Peter Åslund, Hannes Vomhoff and Alexander Waljanson, STFI-Packforsk AB, Sweden
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Abstract:
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The deformation of webs made of chemical and mechanical pulp during and after a suction pulse was investigated. A large deformation was observed when the suction pulse was applied. After the suction pulse, a considerable expansion of the web took place, probably an effect of rewetting.
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Issue:
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Volume 23, 2008, Issue No. 4
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Pages:
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403-408
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Online Date:
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December 15, 2008
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DOI:
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10.3183/NPPRJ-2008-23-04-p403-408
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Keywords:
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Compression, Displacement, Rewetting, Suction box, Vacuum, Water removal
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External rewetting after suction box dewatering
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Peter Åslund, Hannes Vomhoff and Alexander Waljanson, STFI-Packforsk AB, Sweden
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Abstract:
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A method has been developed to enable measurement of external rewetting during suction box dewatering. Under the process conditions investigated, rewetting accounted for a dry content decrease of between 3 and 6%.
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Volume 23, 2008, Issue No. 4
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Pages:
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409-414
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Online Date:
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December 15, 2008
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DOI:
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10.3183/NPPRJ-2008-23-04-p409-414
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Keywords:
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Compression, Displacement, Forming fabric, Laboratory equipment, Rewetting, Suction box, Vacuum, Water removal
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Web deformation during membrane-assisted dewatering
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Peter Åslund and Hannes Vomhoff, STFI-Packforsk AB, Sweden
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Abstract:
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Membrane-assisted dewatering was evaluated on a laboratory suction box in which membranes were placed on the top of the web. A significantly higher web compression was observed when a membrane was used, but a higher rewetting lowers the dry content of the web.
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Volume 23, 2008, Issue No. 4
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Pages:
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415-419
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Online Date:
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December 15, 2008
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DOI:
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10.3183/NPPRJ-2008-23-04-p415-419
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Keywords:
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Compression, Displacement, Laboratory Apparatus, Rewetting, Suction box, Vacuum, Water removal
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Wood pulp based filters for removal of sub-micrometer aerosol particles
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Jingliang Mao, University of British Columbia, Canada, Biljana Grgic and Warren H. Finlay, University of Alberta, Canada, John F. Kadla and Richard J. Kerekes, University of British Columbia, Canada
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Abstract:
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Air filters produced from highly surface fibrillated dry wood pulp were shown to have capture efficiencies of particles in the 300 nanometre range and pressure losses close to those typical of N95 commercial respirator filters.
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Issue:
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Volume 23, 2008, Issue No. 4
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Pages:
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420-425
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Online Date:
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December 15, 2008
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DOI:
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10.3183/NPPRJ-2008-23-04-p420-425
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Keywords:
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Aerosol particles, Air filters, Fibrillated fibres, Filtration efficiency, Freeze-drying, Nanoscale particles, Wood pulps
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The role of fiber entanglement in the strength of wet papers
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Marcius H. de Oliveira, Milan Maric and Theo G.M. van de Ven, McGill University, Montreal, Canada
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Abstract:
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It is shown that capillary forces are too weak to keep wet paper together. Experiments with mixtures of pulp fibers and flexible microfibrils or rigid glass fibers are consistent with the idea that wet strength originates from entanglements friction.
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Issue:
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Volume 23, 2008, Issue No. 4
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Pages:
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426-431
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Online Date:
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December 15, 2008
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DOI:
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10.3183/NPPRJ-2008-23-04-p426-431
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Keywords:
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Capillary forces, Cellulose microfibrils, Entanglement friction, Fiber crossings, Liquid bridges, Wet paper friction, Wet web strength
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Experimental techniques for characterization of elastic-plastic material properties in paperboard
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Mikael Nygårds, STFI-Packforsk AB, Sweden
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Abstract:
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Four experimental techniques to characterize elastic-plastic material properties of the different plies in paperboard are presented. The different plies were separated by grinding and mechanical properties were determined in both the in-plane and out-of-plane directions.
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Volume 23, 2008, Issue No. 4
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Pages:
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432-437
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Online Date:
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December 15, 2008
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DOI:
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10.3183/NPPRJ-2008-23-04-p432-437
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Keywords:
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Compressive test, Mechanical properties, Shear test, Stress strain properties, Tensile test
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Simultaneous characterization of coated paper topography and optical contrast by near-field scanning optical microscopy (NSOM)
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Deqiang Ma and R. Douglas Carter, KaMin LLC, Macon, USA, David Haefner and Aristide Dogariu, University of Central Florida, Orlando, USA
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Abstract:
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NSOM measures simultaneously both local topography and optical contrast better than conventional far-field techniques. Adding fine platy kaolin increased correlation lengths resulting in smoother varying surface. Surface roughness and correlation length of the topography affect surface anisotropy and optical properties.
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Issue:
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Volume 23, 2008, Issue No. 4
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Pages:
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438-443
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Online Date:
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December 15, 2008
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DOI:
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10.3183/NPPRJ-2008-23-04-p438-443
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Keywords:
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Coated papers, Near-field scanning optical microscopy (NSOM), Optical contrast, Topography
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Abstract:
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Annual index for 2008
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