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    Author(s): David W. VaheyJohn M. Considine
    Date: 2010
    Source: Appita journal. Vol. 63, no. 1 (Jan./Mar. 2010): pages 27-31, 41.
    Publication Series: Miscellaneous Publication
    PDF: View PDF  (306.84 KB)

    Description

    Fibres that acquire a z-direction tilt in the forming process help bond adjacent strata of the paper sheet, increasing z-direction shear. Fibre tilt manifests itself as a measurement difference when directionally sensitive tests are conducted “toward headbox” or “toward reel.” Seven of eight different paper grades ranging in grammage from 73 to 268 g/m2 were found to show this difference for Scott-internal-bond tests, directional-brightness tests, or both. Test results were compared for 180° rotations in the machine direction and cross-machine direction. Three-eights of the rotations showed significant directional effects at the 75–100% confidence level, including roughly equal numbers of Scott bond and brightness tests. However, the two tests did not reinforce each other strongly, possibly because of depth variations in z-direction tilt. A model emphasizing tilt of MD fibres caused by rush or drag conditions was well supported by Scott-bond testing. Directional effects in CD testing appear to require a more complex model based on cross flows in the forming section.

    Publication Notes

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    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.

    Citation

    Vahey, David W.; Considine, John M. 2010. Tests for z-direction fibre orientation in paper. Appita Journal. 63(1): 27-31, 41.

    Keywords

    Fibre tilt, grain, felting, z-direction, directionality, running direction, extension, shear, Scott internal bond, brightness, tape pull, fibre pull, ply-bond, sheet-splitting, Student’s t-test, confidence, significance, Fourdrinier, rush, drag, cross flows, paper, mechanical properties, testing, papermaking, orientation, fibers, optical measurements, optical properties, fiber analysis, fiber properties, dimensional stability, shear strength, microfibril angle, brightness, fiber orientation

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https://www.fs.usda.gov/treesearch/pubs/36617