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Bernt I.,Kelheim Fibres GmbH | Eckhart R.,CD Laboratory for Surface Chemical and Physical Fundamentals of Paper Strength
International Paperworld IPW | Year: 2013

Viscose fibers are versatile fibers made from 100% of cellulose, sharing all the advantages this natural polymer offers. As a man-made fiber, shape as well as functionality of the fiber can be controlled in various stages of the production process. The incorporation of even small percentages of viscose fibers into paper can be used to fine-tune paper characteristics. While round Danufil fibers are mainly used to improve bulk and porosity of papers, flat viscose fibers do not increase the volume of the paper but do give a stronger improvement of tensile strength. Kelheim Fibers produces short-cut viscose in cut-lengths from 3 to 12 mm and in a coarseness from 0.7 to 28 dtex, which corresponds to a fiber thickness of about 8 μm to 45 μm for a round fiber cross-section. A new development by Kelheim Fibers is the Leonardo fiber. The Leonardo fiber displays an almost completely smooth fiber surface. Source


Gilli E.,University of Graz | Gilli E.,CD Laboratory for Surface Chemical and Physical Fundamentals of Paper Strength | Gilli E.,Joanneum Research | Schennach R.,University of Graz | Schennach R.,CD Laboratory for Surface Chemical and Physical Fundamentals of Paper Strength
Applied Optics | Year: 2012

The measurement of the bonded area of pulp fibers has been an unsolved issue in paper science for more than 40 years. By the use of an established pulp fiber model, and a 4 × 4 transfer matrix formalism we simulated the optical behavior of pulp fibers in a modified imaging ellipsometer, and we demonstrate that there are rather strong symmetries in the ellipsometric angles ψ and Δ when comparing single fibers, unbonded fiber crossings, and fiber-fiber bonds. Based on these symmetries we propose and test an algorithm that allows to distinguish the three cases (single fibers, unbonded fiber crossings, and fiber-fiber bonds) in the analysis of ellipsometric data. © 2012 Optical Society of America. Source


Weber F.,CD Laboratory for Surface Chemical and Physical Fundamentals of Paper Strength | Weber F.,University of Graz | Koller G.,University of Graz | Schennach R.,CD Laboratory for Surface Chemical and Physical Fundamentals of Paper Strength | And 3 more authors.
Cellulose | Year: 2013

In this paper the influence of charged species on the sheet strength of viscose fibres was investigated. Four samples of chemical modified viscose fibres, as well as a reference fibre were studied. The swelling of these viscose fibres and the breaking length of hand sheets have been determined. Comparing the results, the influence of both, swelling and surface charge on the bonding force, is evident. The allocation of the charges, induced by cationic starch and Carboxmethylcellulose, has been analyzed by Titration, attenuated total reflection spectroscopy (ATR) and X-ray photoelectron spectroscopy (XPS). Titration was used to make a first estimation of the charge distribution within the fibre. Using ATR and XPS, more detailed information about the surface charge has been achieved. All measurement methods showed a significant amount of charge on the fibre surface. © 2013 Springer Science+Business Media Dordrecht. Source


Adriana G.,University of Graz | Jussi L.,CD Laboratory for Surface Chemical and Physical Fundamentals of Paper Strength | Robert S.,CD Laboratory for Surface Chemical and Physical Fundamentals of Paper Strength | Robert S.,University of Graz | Franz S.,University of Graz
Thermochimica Acta | Year: 2013

Dynamic mechanical analysis combined with relative humidity (DMA-RH) was used to examine the viscoelastic properties of standard Kraft and extensible Clupak paper in dry and humid atmosphere. Knowledge regarding these viscoelastic properties combined with the natural hygroscopicity of paper is fundamental for the prediction of paper behaviour under stress conditions. Results from DMA-RH under dynamic (frequency/strain experiments) and static measurement modes (creep/recovery experiments) indicated that the change of paper structure during the Clupak process is significant. Marked changes in elongation and stiffness as well as relaxation ability of Clupak paper were found. DMA-RH allows the combining multiple conditions (frequency, temperature, time, load, and humidity) during a single measurement and it can thus simulate similar conditions to those in paper processing and product-use. © 2013 Elsevier B.V. Source


Gilli E.,CD Laboratory for Surface Chemical and Physical Fundamentals of Paper Strength | Gilli E.,Graz University of Technology | Kornschober M.,Graz University of Technology | Schennach R.,CD Laboratory for Surface Chemical and Physical Fundamentals of Paper Strength | Schennach R.,Graz University of Technology
Infrared Physics and Technology | Year: 2012

We present an optical setup for variable angle mid infra red spectroscopic ellipsometry. The arrangement can be placed into the sample compartment of a Bruker ifs66v/s vacuum Fourier transform infrared spectrometer. A first prototype of the setup has been tested in the spectral range from 650 cm -1 to 4000 cm -1 and can measure incidence angles between 8° and 87°. We compare the measured data to reference measurements with a commercial variable angle infrared spectroscopic ellipsometer. The comparison gives a proof of concept for the discussed optical arrangement. © 2011 Elsevier B.V. All rights reserved. Source

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