Showing papers by "Warren Batchelor published in 1997"

Forces on fibres in low-consistency refining : Normal force

Abstract: Une equation a ete developpee afin de predire la force normale appliquee sur un floc idealise lors de sa compression entre les lames d'un raffineur. L'equation repose sur trois hypotheses ayant trait aux flocs : ils sont de forme spherique et les fibres constituantes sont disposees uniformement ; ils ne peuvent supporter une charge normale tant que la majorite des fibres ne sont pas en contact ; ils ont un comportement lineaire et elastique en compression. La validite de l'equation a ete verifiee dans un raffineur monolame operant a 1 rpm en utilisant des flocs formes a partir de fibres de nylon. Les mesures ont montre un bon accord avec la theorie. Les resultats indiquent que la force normale s'accroit rapidement dans les premiers 2-3 mm du croisement entre les lames et qu'elle demeure essentiellement constante par la suite.

Measuring the fibril angle of fibres using confocal microscopy

Abstract: A new technique for measuring the S2 fibril angle in wood fibres using a confocal microscope in reflectance mode is presented. Polarized laser light is reflected from the fibre and passed through an analyser polaroid crossed with the polarization of the illuminating laser beam. The measured intensity goes through a minimum whenever the orientation of the fibrils matches the polarization of either the incoming laser light or the analyser. As the confocal optics of the microscope allows detection of only light scattered from on or around the focal plane of the microscope, optical interference from the second fibre wall is eliminated. Thus the fibril angle can be measured without extensive sample preparation. A number of examples of the new method are presented.

Measuring the Fibril Angle of Bleached Fibres Using Micro-Raman Spectroscopy

Abstract: A new technique for measuring the fibril angle of bleached pulp fibres is presented. It uses micro-Raman spectroscopy and involves measuring the ratio of the 1094 to 1120 cm -1 peak intensities as a function of angle. It is compared with a direct method of measuring of the fibril angle (cell wall striation method) and with two indirect methods (polarized light microscopy and pit aperture angle methods). A good correlation was obtained with the direct method indicating that the Raman method can accurately determine fibril angles in pine fibres. Poor correlations with the indirect methods suggest that these methods are inherently inaccurate.