Title: Nanoindentation of bleached and refined pulp fibres

Authors: Ramesh B. Adusumalli; Raphaël Passas; I. Sreedhar; Balaji Krishnamurthy; Boopathy Kombaiah; Alex Montagne

Addresses: Department of Chemical Engineering, BITS Pilani-Hyderabad Campus, Shameerpet, Hyderabad, 500078, India ' Laboratory of Pulp and Paper Science and Graphic Arts, Grenoble INP-Pagora Laboratoire Génie des Procédés Papetiers (LGP2), 461 rue de la Papeterie CS 10065 38402, Saint-Martin d'Hères, Cedex, France ' Department of Chemical Engineering, BITS Pilani-Hyderabad Campus, Shameerpet, Hyderabad, 500078, India ' Department of Chemical Engineering, BITS Pilani-Hyderabad Campus, Shameerpet, Hyderabad, 500078, India ' Laboratory for Mechanics of Materials and Nanostructures, EMPA - Materials Science & Technology, Feuerwerkstr. 39, CH-3602 Thun, Switzerland ' Laboratory for Mechanics of Materials and Nanostructures, EMPA – Materials Science and Technology, Feuerwerkstr. 39, CH-3602 Thun, Switzerland

Abstract: In this study, an attempt has been made to determine the mechanical properties of the wood pulp cell wall after pulping, bleaching and refining by means of nanoindentation in comparison with flax and lyocell fibres. Based on the indents performed on single fibre cell wall cross-sections, it has been found that bleaching and refining processes are causing reduction in indentation modulus and hardness values. It is assumed that the reduction is attributed to the change in lignin content as well as microfibril angle. Surprisingly, refined pulp fibres and lyocell have the same hardness and indentation modulus, which conforms that no residual lignin is present in the refined pulp. The bast fibre, flax, extracted without Kraft cooking revealed higher indentation modulus (23 GPa) and hardness (0.50 GPa) compared to wood pulp fibres.

Keywords: nanoindentation; wood pulp fibres; flax fibres; lyocell fibres; cell wall; bleached pulp fibres; refined pulp fibres; nanotechnology; indentation modulus; hardness; lignin content; microfibril angle.

DOI: 10.1504/IJMATEI.2014.060320

International Journal of Materials Engineering Innovation, 2014 Vol.5 No.2, pp.138 - 150

Available online: 10 Apr 2014 *

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