The Use of Micro-Tensile Testing to Assess Weathering Decay and Oxidative Degradation of Wooden Items

IRG/WP 10-20433

C Mai, Yanjun Xie, Zefang Xiao, P D Evans, H Militz

This paper presents a method to study the weathering performance of wooden items and to assess the oxidative degradation of wood via the Fenton reaction. Weathering resistance and photo-stability of wood was tested using pine wood (Pinus sylvestris) veneer strips measuring approximately 60 µm in thickness. The veneer strips were treated using a reactive chemical to impart surface protection. The artificially weathered veneers were characterised regarding tensile strength loss as well as by means of infrared spectroscopy. The chemical treatment reduced the tensile strength of the veneer strips. During artificial weathering, however, the strength loss of the treated veneers was clearly lower than that of the controls. The shape of the veneers was preserved due to the treatment. In a second approach veneers strips were used to study wood degradation by the Fenton’s reagent in order to minic the long-term deterioration of archaeological wood from marine environments. Veneer strips were incubated in acetate buffer (pH 4) containing hydrogen peroxide and Fe ions (Fenton’s reagent) and tensile properties (measured in a zero-span mode) were determined. Varying the type of iron (ferrous or ferric sulphate) with H2O2 did not yield significant differences in the rates of H2O2 and tensile strength reduction. However, increasing the amount of wood material (the number of wood strips) in the reaction mixture increased Fe(III) reduction in solution indicating that wood constituents participated in this reaction. Increasing concentrations of Fe(III) in the reaction mixture resulted in a decrease in H2O2 in solution. Despite an increase in iron concentration and H2O2 decomposition under these conditions, a uniform and consistent strength loss of 30% was observed at all Fe(III) concentrations tested. At fixed Fe(III) concentrations, increasing the H2O2 concentration linearly increased the strength loss of the veneers.


Keywords: thin veneer strips, weathering, tensile strength, infrared spectroscopy, electron microscopy, Fenton reaction, oxidative degradation

Conference: 10-05-09/13 Biarritz, France


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