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®.

Effects of environmental conditions on physical and mechanical properties of thermally modified wood

2019 ◽  
Vol 49 (11) ◽  
pp. 1434-1440 ◽  
Author(s):  
Chenyang Cai ◽  
Henrik Heräjärvi ◽  
Antti Haapala
Keyword(s):  
Norway Spruce ◽  
Scots Pine ◽  
Moisture Absorption ◽  
Brinell Hardness ◽  
Physical And Mechanical Properties ◽  
Thermal Modification ◽  
The Difference ◽  
Thermally Modified Wood ◽  
Modified Wood ◽  
Exposure Conditions

The behaviour of industrially modified wood has not been systematically evaluated in controlled exposure conditions. The objective of this study was to assess the equilibrium moisture content (EMC), dimensions, and Brinell hardness of thermally modified wood in different conditions of temperature and relative humidity (RH). Tested materials consisted of European ash (Fraxinus excelsior L.), Norway spruce (Picea abies (L.) Karst.), and Scots pine (Pinus sylvestris L.) that were thermally modified according to ThermoWood industrial processes into the classes Thermo-S and Thermo-D. The properties were measured at the following conditions: 20 °C and 65% RH, 10 °C and 90% RH, and 30 °C and 30% RH. The results show that the reduction of EMC and the improvement in dimensional stability are dependent on the degree of thermal modification. Thermal modification was more resistant to moisture absorption at 20 °C and 65% RH than at 10 °C and 90% RH and 30 °C and 30% RH, and the more severe modification decreased the difference among different exposure conditions. The tangential–radial ratio of swelling and shrinkage was higher for thermally modified wood than for nonmodified wood. Brinell hardness of modified Scots pine and Norway spruce did not differ significantly from that of nonmodified wood in normal and dry conditions, but the more humid conditions increased the difference by 12%–17%.

scholarly journals Preliminary Study on the Physical and Mechanical Properties of Poplar Wood Modified by Waterborne Glucose Silicone Resin

2020 ◽  
Author(s):  
Qiangqiang Liu ◽  
Haojia Du ◽  
Wenhua Lyu
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Mass Fraction ◽  
Untreated Wood ◽  
Physical And Mechanical Properties ◽  
Silicone Resin ◽  
Poplar Wood ◽  
Characteristic Structure ◽  
Organic Hybrid ◽  
Modified Wood

In order to improve the performance of soft plantation wood, an environmentally friendly inorganic-organic hybrid wood modifier was developed. First, using urea and melamine as crosslinking agents, the waterborne glucose silicone resin (MUG) was prepared with glucose under the catalysis of inorganic acid and metal ions. Then MUG resin was diluted to 10% and 20% mass fraction, and compounded with sodium silicate (S) of 20% and 10% mass fraction, so the inorganic-organic hybrid G10S20 and G20S10 wood modifier were obtained respectively. Then plantation poplar wood (Populus tomentosa) were impregnated and modified with them. Their physical and mechanical properties were tested and compared with those of the wood treated with S of 20% mass fraction (S20). Infrared analysis showed that amino resin characteristic structure (CO-NH-) existed in MUG resin. The resin has good permeability. Compared with S20 modified wood, the degree of shrinkage of G10S20 or G20S10 modified wood is reduced, their moisture absorption is reduced, and their dimensional stability is improved. Waterborne glucose silicone modifier can effectively improve the wood density, modulus of elasticity, modulus of rapture and compression strength. SEM analysis showed that the cell wall of G20S10 modified wood was significantly thicker than the untreated wood, and there were columnar and granular solid substances attached in some cell cavities, ducts and corners, etc. EDX showed that the number of Si elements on the cell wall was significantly increased compared with the control, indicating that the modifier effectively entered the wood cell wall. The waterborne glucose silicone resin can greatly improve the physical and mechanical properties of wood through organic-inorganic hybridization. It is a green, non-formaldehyde, eco-friendly, low cost, compound wood modifier with broad application prospects.

Study of Vinyltrimethoxysilane Modified Wood Flour/HDPE Composites

2011 ◽  
Vol 183-185 ◽  
pp. 2148-2153
Author(s):  
Chun Tao Li ◽  
Wei Hong Wang ◽  
Qing Wen Wang ◽  
Yan Jun Xie ◽  
Yong Ming Song ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Water Resistance ◽  
Wood Flour ◽  
Untreated Wood ◽  
Solution Concentration ◽  
Added Value ◽  
Grafting Reaction ◽  
Interfacial Compatibility ◽  
Modified Wood

Wood plastic composites (WPC) are a new type of green environmental composites with high performance and added value. In this paper, poplar wood flour was modified with vinyltrimethoxysilane(A-171) to improve the interfacial compatibility and enhance the interfacial bonding between the polar wood flour and nonpolar plastics. Then the modified wood flour was blended with high density polyethylene (HDPE) and prepared composites by extrusion. The effects of amount and solution concentration of A-171 on the properties of WPC were investigated. FTIR analysis indicated that polycondensation grafting reaction occurred between A-171 and wood flour. Compared to untreated wood flour/HDPE composites, both mechanical properties and water resistance of the composites were improved and presented optimal performance when the dosage of A-171 was 4%. The storage modulus G' and viscosity η*of the composites decreased but the loss tangent tanδ increased compared to the untreated composites. G' and η* raised with the increase of A-171, however, tanδ decreased. Solution concentration of A-171 did not show significant effect on the mechanical properties of composites, but water resistance of composites decreased with the increase of solution concentrateon of A-171.

Moisture Dynamics in Norway Spruce and Scots Pine during Outdoor Exposure in Relation to Different Surface Treatments and Handling Conditions

Holzforschung ◽  
2003 ◽  
Vol 57 (2) ◽  
pp. 219-227 ◽  
Author(s):  
T. Elowson ◽  
M. Bergström ◽  
M. HämälÄinen
Keyword(s):  
Norway Spruce ◽  
Scots Pine ◽  
Principal Component ◽  
Production Method ◽  
Outdoor Exposure ◽  
Moisture Uptake ◽  
High Moisture ◽  
Large Spread ◽  
Handling Method ◽  
Moisture Dynamics

Summary Moisture dynamics in wood during weather exposure as affected by species, origin, production method and painting system were studied for nine years on 170 samples. The moisture content (MC, by dry base) was measured on 67 occasions. Principal component analysis was used for data reduction and pattern recognition. The investigation included two species; Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L. (Karst)), and showed that the painting method affected the moisture dynamics most. In addition, species and type of wood were important factors, and for pine sapwood also the production method used had an influence on the moisture dynamics. Heartwood of pine had a stable development with low MC throughout the experimental time, regardless of surface treatment or handling method. The pine sapwood samples, on the other hand, had higher average MC and much faster dynamics. For painted and endsealed pine sapwood samples, the drying method was not significant for the MC dynamics, but water storage led to a higher and faster moisture uptake than for samples that were not water-stored. For untreated pine sapwood samples, air-drying led to the highest and fastest moisture uptake, but on the whole this group had unacceptably high moisture uptake. The spruce samples showed very different behaviour depending on whether they were surface treated or not. Painted and endsealed spruce led to two distinct groups, one with moisture dynamics similar to pine heartwood and one with very high moisture uptake and large spread more similar to pine sapwood. Most untreated spruce samples had moisture dynamics comparable to those of pine heartwood.

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

Preparation and Property of Wood Polymer Composite with a Two-Step Method

2009 ◽  
Vol 79-82 ◽  
pp. 1527-1530
Author(s):  
Yong Feng Li ◽  
Yi Xing Liu ◽  
Hai Peng Yu ◽  
Wen Shuai Chen
Keyword(s):  
Mechanical Properties ◽  
Porous Structure ◽  
Polymer Composite ◽  
Cell Walls ◽  
Untreated Wood ◽  
Hydroxyl Group ◽  
Step Method ◽  
Wood Polymer ◽  
Wood Polymer Composite ◽  
Modified Wood

Wood as a porous structure has weak durability and unsatisfactory mechanical properties which limits its utilization. For this reason, the study presents a two-step method to prepare a new modified wood material—Wood Polymer Composite. Maleic anhydride(Man) firstly penetrates into the porous structure of wood, followed by a reaction with wood cell walls. Then, Styrene(St) with some Man and a few amount of initiator, AIBN, permeate through the whole wood and react with the above modified wood. The structural characterization of wood polymer composite with SEM and FTIR indicates that Man reacts successfully with the hydroxyl group of wood cell wall by its anhydride group, and further reacts fully with styrene as a free radical copolymerization form by its double bond; and thus the polymer fills in wood cell lumina as a solid form, which combines the wood cell walls without any evident crack. The testing results of properties show that the mechanical properties of wood polymer composite increase by about 50%-250% over those of unmodified wood, and its durability improve 1.9-4.89 times than untreated wood.

The toughness of hygrothermally modified wood

Holzforschung ◽  
2015 ◽  
Vol 69 (7) ◽  
pp. 851-862 ◽  
Author(s):  
Mark Hughes ◽  
Callum Hill ◽  
Alexander Pfriem
Keyword(s):  
Mechanical Properties ◽  
Coupling Agent ◽  
Thermal Modification ◽  
Point Of View ◽  
Interfacial Coupling ◽  
Modification Process ◽  
Thermally Modified Wood ◽  
Wall Components ◽  
Modified Wood

Abstract The mechanical properties of thermally modified wood are discussed with regard to toughness. The molecular origins of the mechanical properties and, in particular, the role of the hemicelluloses are considered. The important role of water and its interaction with the cell wall components is also examined. The properties are discussed from the point of view of composite theory, with the three main macromolecular components acting as reinforcement, matrix and interfacial coupling agent. The important role that hemicelluloses play as a coupling agent between the cellulosic microfibril reinforcement and the lignin-rich matrix is highlighted. Destruction of the hemicelluloses during the thermal modification process has a profound effect upon the mechanical behaviour.

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.

Mechanical properties and decay resistance of Scots pine (Pinus sylvestris L.) sapwood modified by vinyl acetate-epoxidized linseed oil copolymer

Holzforschung ◽  
2016 ◽  
Vol 70 (9) ◽  
pp. 885-894 ◽  
Author(s):  
Shengzhen Cai ◽  
Mohamed Jebrane ◽  
Nasko Terziev ◽  
Geoffrey Daniel
Keyword(s):  
Mechanical Properties ◽  
Pinus Sylvestris ◽  
Vinyl Acetate ◽  
Scots Pine ◽  
Linseed Oil ◽  
Untreated Wood ◽  
Decay Resistance ◽  
Mechanical Tests ◽  
Slight Reduction ◽  
Epoxidized Linseed Oil

Abstract Equilibrium moisture content (EMC), mechanical properties, and durability of Scots pine (Pinus sylvestris L.) sapwood modified by vinyl acetate epoxidized linseed oil (WVA-ELO) have been studied. Microscopic observations revealed that the impregnated copolymer is mainly in cell walls, rays, resin canals, and a small fraction in the cell lumens. Under the same climate conditioning, the EMC of the treated wood was in the range of 6.0%–8.2%, which was significantly lower than that of untreated wood (about 12%). Mechanical tests performed on paired samples (control and treated) showed a slight reduction on the mechanical properties of WVA-ELO. The decay resistance against basidiomycete fungi of WVA-ELO was significantly improved as demonstrated by laboratory tests. It was found that 8% weight percentage gain (WPG) was sufficient to ensure decay resistance against the test fungi with <5% mass loss (ML), which led to durability class (DC) of 2.

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