Resistance of thermo-hygro-mechanically (THM) densified wood to degradation by white rot fungi

Oleksandr Skyba, Peter Niemz 2 ,  and Francis W.M.R. Schwarze 1
  • 1 Swiss Federal Laboratories of Material Testing and Research (EMPA), Wood Laboratory, St. Gallen, Switzerland
  • 2 ETH Zurich, Institute for Building Materials, ETH-Hönggerberg, Zurich, Switzerland

Abstract

Colonisation and degradation by the white rot fungi, Trametes versicolor and T. pubescens, were studied in wood of Norway spruce and beech subjected to three different treatments: (1) hygro-thermal treatment (160°C and 180°C), (2) mechanical densification, and (3) thermo-hygro-mechanical (THM) treatment including densification and post-treatment at different temperatures (140°C, 160°C and 180°C). The weight losses induced by the fungi were lowest in THM-densified woods. However, volume related numerical indicators for decay susceptibility did not show any significant improvements of THM-densified woods against both fungi. Analysis of the chemical composition of treated wood species revealed slight alterations in the content of polysaccharides and lignin. White rot fungi circumvented conditions restricting hyphal growth within the occluded tracheid lumina by hyphal tunnelling in the secondary walls of fibre tracheids in beech or by forming bore holes that transversally penetrated cell walls of earlywood tracheids in THM-densified spruce. The studies indicate that THM-densified beech and Norway spruce wood may have some potential in utility class 3 but are inappropriate for use in utility class 4.

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Holzforschung is an international scholarly journal that publishes cutting-edge research on the biology, chemistry, physics and technology of wood and wood components. High quality papers about biotechnology and tree genetics are also welcome. Rated year after year as one of the top scientific journals in the category of Pulp and Paper (ISI Journal Citation Index), Holzforschung represents innovative, high quality basic and applied research.

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