Correlation of Studies between Colour, Structure and Mechanical Properties of Commercially Produced ThermoWood® Treated Norway Spruce and Scots Pine

Abstract

The thermal modification of wood has become the most-commonly commercialised wood modification process globally, with the ThermoWood® process currently being the most dominant. As with all commercial processes, there is a need to have a robust quality control system, with several small–scale studies undertaken to date investigating quality control using a range of analytical methods, culminating in a multi-year assessment of colour as a means of quality control. This study, as an extension to this multi-year assessment, further explores the colour of Norway spruce and Scots pine commercially modified by the ThermoWood® S and D processes, respectively, along with the mechanical properties and structural characterisation by Fourier transform infrared (FT–IR) spectroscopy and principal component analysis (PCA) to ascertain further correlations between colour and other measurable properties. Infrared spectroscopy indicated modifications in the amorphous carbohydrates and lignin, whereas the use of PCA allowed for the differentiation between untreated and modified wood. Colour measurements indicated reduced brightness, and shifting toward red and yellow colours after thermal modification, hardness values decreased, whereas MOE and MOR values were similar for modified wood compared to unmodified ones. However, by combining the colour measurements and PC scores, it was possible to differentiate between the two modification processes (Thermo–S and Thermo–D). By combining the mechanical properties and PC scores, it was possible to differentiate the untreated wood from the modified ones, whereas by combining the mechanical properties and colour parameters, it was possible to differentiate between the three groups of studied samples. This demonstrates there is a degree of correlation between the test methods, adding further confidence to the postulation of using colour to ensure quality control of ThermoWood®.

Chemotaxonomic Classification of Peucedanum japonicum and Its Chemical Correlation with Peucedanum praeruptorum, Angelica decursiva, and Saposhnikovia divaricata by Liquid Chromatography Combined with Chemometrics

“…The results of clustering analyses demonstrate that the PJ samples showed better chemical proximity with the PP samples than the SD samples due to the PC (=dimension score in k -means) scores of the PJ samples being closer to those of the PP samples than the SD samples [ 28 , 29 ].…”

Elements of Designing Upholstered Furniture Sandwich Frames Using Finite Element Method

“…These species, in addition to their high availability, have characteristics that allow them to be used in lightweight furniture structures [ 3 , 4 ]. Natural and modified wood materials simultaneously have strength parameters that meet the requirements for furniture structure design [ 5 , 6 , 7 , 8 ].…”

Impact of Heat Treatment of Spruce Wood on Its Fire-Technical Characteristics Based on Density and the Side Exposed to Fire

“…Studies demonstrate that heattreated wood has several positive properties compared with untreated wood, such as increased biological resistance and resistance to weather and sunlight [2][3][4], reduction of equilibrium moisture content [4][5][6], reduction of the heat transfer coefficient [7], improved dimensional stability [8][9][10], reduction of some undesirable substances (resins, polysaccharides) [11,12], thermal insulation [6,13,14], and aesthetic properties in the form of a darker decorative colour [15][16][17][18][19]. The disadvantage is the deterioration of its mechanical properties [3,4,[20][21][22][23].…”