scholarly journals Influence of heat transferring media on durability of thermally modified wood

BioResources ◽  
2010 ◽  
Vol 6 (1) ◽  
pp. 356-372 ◽  
Author(s):  
Olov Karlsson ◽  
Ekaterina Sidorova ◽  
Tom Morén
Keyword(s):  
Mass Loss ◽  
Norway Spruce ◽  
Scots Pine ◽  
Wood Species ◽  
Rapeseed Oil ◽  
Linseed Oil ◽  
Thermal Modification ◽  
Saturated Steam ◽  
European Aspen ◽  
Low Mass

Studies on the durability and dimensional stability of a series of hardwoods and softwoods after thermal modification in vegetable oils and in steam atmospheres have been performed. Mass loss after exposure to Coniophora puteana (BAM Ebw.15) for 16 weeks was very low for European birch, European aspen, Norway spruce, and Scots pine thermally modified in a linseed oil product with preservative (for 1 hour at 200 oC). Fairly low mass losses were obtained for wood thermally modified in linseed-, tung- and rapeseed oil, and losses were related to the wood species. Low mass loss during rot test was also found for Norway spruce and Scots pine modified in saturated steam at 180 oC. Water absorption of pine and aspen was reduced by the thermal treatments and the extent of reduction was dependent on wood species and thermal modification method. Thermally modified aspen was stable during cycling climate tests, whereas pine showed considerable cracking when modified under superheated steam conditions (Thermo D). At lower modification temperature (180 oC) an increase in mass after modification in rapeseed oil of spruce, aspen and sapwood as well as heartwood of pine was observed, whereas at high temperature (240 oC) a mass loss could be found. Oil absorption in room tempered oil after thermal modification in oil was high for the more permeable aspen and pine (sapwood).

Effect of initial moisture content on the anti-swelling efficiency of thermally modified Scots pine sapwood treated in a high-pressure reactor under saturated steam

Holzforschung ◽  
2014 ◽  
Vol 68 (3) ◽  
pp. 323-326 ◽  
Author(s):  
Lauri Rautkari ◽  
Callum A.S. Hill
Keyword(s):  
High Pressure ◽  
Relative Humidity ◽  
Moisture Content ◽  
Mass Loss ◽  
Scots Pine ◽  
Initial Moisture Content ◽  
Thermal Modification ◽  
Saturated Steam ◽  
Modification Process ◽  
Modified Wood

Abstract The effects of initial moisture content (MC) on anti-swelling efficiency (ASE), mass loss (ML), and equilibrium MC (EMC) at 65% relative humidity of thermally modified Scots pine sapwood under saturated steam (TMSA) has been investigated. ML during the TMSA process was higher with the specimens containing moisture before modification compared with initially dry specimens. Surprisingly, the EMC of the modified specimens with initial moisture was higher than that observed with the modified wood that was initially dry before the modification process. Higher initial MC before thermal modification results in a lower ASE.

Manganese dynamics in decomposing needle and leaf litter — a synthesis

2013 ◽  
Vol 43 (12) ◽  
pp. 1127-1136 ◽  
Author(s):  
Björn Berg ◽  
Björn Erhagen ◽  
Maj-Britt Johansson ◽  
Lars Vesterdal ◽  
Mikaeel Faituri ◽  
...  
Keyword(s):  
Mass Loss ◽  
Norway Spruce ◽  
Scots Pine ◽  
Deciduous Species ◽  
Limit Values ◽  
Litter Mass ◽  
Litter Mass Loss ◽  
Species Groups ◽  
Mn Concentration ◽  
Mn Concentrations

The aim of the present synthesis paper was to determine whether concentration changes and net release of manganese (Mn), as related to accumulated litter mass loss, are related to initial Mn concentration, mean annual temperature (MAT), mean annual precipitation (MAP), and tree genus or species. We also examined whether limit values for decomposition are related to initial litter Mn concentration, MAT, and MAP. We compiled 84 foliar litter decomposition studies, conducted mainly in boreal and temperate forest ecosystems, for which Mn dynamics had been well documented. Manganese concentration and amount were related to accumulated litter mass loss at each sampling time for each single study, as well as for (i) all studies combined (n = 748) and (ii) for species groups viz. Norway spruce (Picea abies (L.) Karst.) (n = 284), pine (Pinus) species (n = 330), and deciduous species (n = 214). The changes in Mn concentration with accumulated mass loss followed quadratic functions showing significantly higher Mn concentrations for Norway spruce vs. Scots pine (Pinus sylvestris L.) (p < 0.0001) and vs. deciduous species (p < 0.01), as well as significantly higher for deciduous species vs. Scots pine (p < 0.0001). Manganese release rates were different among the three species groups (p < 0.001). Still, rates were related to initial Mn concentrations (p < 0.001) for all litter types combined and for the three species groups. Norway spruce released Mn more slowly than pine and deciduous species. Rates were related to climatic factors for litter of Norway spruce and deciduous species. Limit values for all litter and for pine species separately were related to Mn (p < 0.001) and MAT (p < 0.001). For Norway spruce, limit values were related to MAT (p < 0.001) and MAP (p < 0.01). It appears that Norway spruce litter retains Mn more strongly in the litter structure, producing humus richer in Mn than does litter of pine and deciduous species.

Effect of extractives and thermal modification on antibacterial properties of Scots pine and Norway spruce

2013 ◽  
Vol 4 (4) ◽  
pp. 248-252 ◽  
Author(s):  
T Vainio-Kaila ◽  
L Rautkari ◽  
K Nordström ◽  
M Närhi ◽  
O Natri ◽  
...  
Keyword(s):  
Norway Spruce ◽  
Scots Pine ◽  
Antibacterial Properties ◽  
Thermal Modification

scholarly journals Modelling the Material Resistance of Wood—Part 1: Utilizing Durability Test Data Based on Different Reference Wood Species

Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 558
Author(s):  
Gry Alfredsen ◽  
Christian Brischke ◽  
Brendan N. Marais ◽  
Robert F. A. Stein ◽  
Katrin Zimmer ◽  
...  
Keyword(s):  
Norway Spruce ◽  
Scots Pine ◽  
Test Data ◽  
Wood Species ◽  
Ring Width ◽  
European Beech ◽  
White Rot ◽  
Species Variation ◽  
Reference Species ◽  
Moisture Performance

To evaluate the performance of new wood-based products, reference wood species with known performances are included in laboratory and field trials. However, different wood species vary in their durability performance, and there will also be a within-species variation. The primary aim of this paper was to compare the material resistance against decay fungi and moisture performance of three European reference wood species, i.e., Scots pine sapwood (Pinus sylvestris), Norway spruce (Picea abies), and European beech (Fagus sylvatica). Wood material was collected from 43 locations all over Europe and exposed to brown rot (Rhodonia placenta), white rot (Trametes versicolor) or soft rot fungi. In addition, five different moisture performance characteristics were analyzed. The main results were the two factors accounting for the wetting ability (kwa) and the inherent protective properties of wood (kinh), factors for conversion between Norway spruce vs. Scots pine sapwood or European beech for the three decay types and four moisture tests, and material resistance dose (DRd) per wood species. The data illustrate that the differences between the three European reference wood species were minor, both with regard to decay and moisture performance. The results also highlight the importance of defined boundaries for density and annual ring width when comparing materials within and between experiments. It was concluded that with the factors obtained, existing, and future test data, where only one or two of the mentioned reference species were used, can be transferred to models and prediction tools that use another of the reference species.

scholarly journals Long-Term Effects of Climate and Litter Chemistry on Rates and Stable Fractions of Decomposing Scots Pine and Norway Spruce Needle Litter—A Synthesis

Forests ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 125
Author(s):  
Björn Berg ◽  
Mikael Lönn
Keyword(s):  
Mass Loss ◽  
Norway Spruce ◽  
Scots Pine ◽  
Late Stage ◽  
Early Stage ◽  
Negative Relationship ◽  
Mean Annual Precipitation ◽  
Mean Annual Temperature ◽  
Long Term Effects ◽  
Limit Values

We have reviewed information on early-, late- and limit-value decomposition stages for litter of Norway spruce (Picea abies) and Scots pine (Pinus silvestris). This synthesis covers c 16 studies/papers made along a climatic gradient; range in mean annual temperature (MAT) from −1 to +7 °C and mean annual precipitation (MAP) from 425 to 1070 mm. Scots pine has an early stage dominated by carbohydrate decomposition and a late stage dominated by decomposition of lignin; Norway spruce has just one stage dominated by lignin decomposition. We used data for annual mass loss to identify rate-regulating factors in both stages; climate data, namely, MAT and MAP, as well as substrate properties, namely, nitrogen (N), acid unhydrolyzable residue (AUR), manganese (Mn). Early-stage decomposition for Scots pine litter was dominated positively by MAT; the late stage was dominated negatively by MAT, N, and AUR, changing with decomposition stage; there was no effect of Mn. Norway spruce litter had no early stage; decomposition in the lignin-dominated stage was mainly negative to MAP, a negative relationship to AUR and non-significant relationships to N and MAT. Mn had a positive relationship. Limit values for decomposition, namely, the accumulated mass loss at which decomposition is calculated to be zero, were related positively to Mn and AUR for Scots pine litter and negatively to AUR for Norway spruce litter. With different sets of rate-regulating factors as well as different compounds/elements related to the limit values, the decomposition patterns or pathways are different.

scholarly journals Effects of heat treatment systems on the physical properties of coated Scots pine (Pinus sylvestris L.) and poplar (Populus euramericana)

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 2708-2720 ◽  
Author(s):  
Ahmet Can
Keyword(s):  
Heat Treatment ◽  
Pinus Sylvestris ◽  
Physical Properties ◽  
Mass Loss ◽  
Scots Pine ◽  
Wood Species ◽  
Color Change ◽  
Vacuum Heat Treatment ◽  
Populus Euramericana ◽  
Water Based

Heat treatment is an environmentally friendly and efficient way to improve the properties of wood species. These treatments alter the substrates and can influence the surface properties of the varnish coatings. This paper investigated the effects of heat treatment on the physical properties of open and close systems Scots pine (Pinus sylvestris L.) and poplar (Populus euramericana) wood, coated with water-based, polyurethane-based, and oil/wax-based varnishes. Heat treatment was applied at the temperatures of 190, 212 °C for pine and 180, 200 °C for poplar, respectively. Color, gloss, and roughness tests were carried out for each of the coatings. Higher mass loss occurred in pine samples with heat treatment as compared to vacuum-heat treatment. Gloss decreased in OIL+WAX treatment and color change increased after the heat treatment, but these results were inhibited with vacuum-heat treatment. Maximum roughness was obtained in PUR varnishes and minimum roughness in OIL + WAX samples. The low roughness values provide some advantages in application.

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

Forests ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1165
Author(s):  
Petteri Torniainen ◽  
Carmen-Mihaela Popescu ◽  
Dennis Jones ◽  
Alexander Scharf ◽  
Dick Sandberg
Keyword(s):  
Mechanical Properties ◽  
Quality Control ◽  
Norway Spruce ◽  
Scots Pine ◽  
Untreated Wood ◽  
Principal Component ◽  
Thermal Modification ◽  
Small Scale ◽  
Colour Measurements ◽  
Modified Wood

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®.

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