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Proceedings Paper

Paper surface diffraction to characterize the fiber orientation distribution
Author(s): Mario Pereira; Jose Teixeira; Paulo Torrao Fiadeiro; Jacques Silvy
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Paper Abstract

Many paper mills use ultrasonic techniques to measure the Tensile Stiffness Index, TSI, of the paper sheet. They then assume that the TSI value is the same as the fibre orientation anisotropy. This is true if the paper is allowed to dry without any internal tension or elongation, but does not apply to paper manufactured in a paper machine. The paper machine introduces tension and elongation as soon as the fibre is placed on the forming fabric. These factors increase through the press section and are accentuated in the drying section. In order to uniquely measure the fibre orientation anisotropy on the surfaces, the proposed method uses replicas of both paper surfaces to produce a laser diffraction pattern. The obtained pattern reveals an elliptical shape, which is related to the fibre orientation anisotropy of the paper surface. By measuring the ellipticity of the diffraction pattern and the deviation with respect to the machine direction, one can quantify the fibre orientation distribution. Different papers from the bench market have been successfully tested with the developed system. This article describes the new developed optical system and its innovative capabilities in the field to produce maps of the fibre orientation of a complete paper sheet surface. A selection of the obtained results to prove its feasibility is also presented.

Paper Details

Date Published: 26 November 2001
PDF: 10 pages
Proc. SPIE 4448, Optical Diagnostics for Fluids, Solids, and Combustion, (26 November 2001); doi: 10.1117/12.449373
Show Author Affiliations
Mario Pereira, Univ. of Beira Interior (Portugal)
Jose Teixeira, Univ. of Beira Interior (Portugal)
Paulo Torrao Fiadeiro, Univ. of Beira Interior (Portugal)
Jacques Silvy, Univ. of Beira Interior (Portugal)

Published in SPIE Proceedings Vol. 4448:
Optical Diagnostics for Fluids, Solids, and Combustion
Carolyn R. Mercer; Soyoung Stephen Cha; Gongxin Shen, Editor(s)

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