Measurement of the uptake of linseed oil in pine by the use of an X-ray microdensitometry technique

Pine sapwood (Pinus sylvestris) was impregnated with linseed oil to three levels of uptake. The distribution of the penetrant was found by taking microdensity measurements of an impregnated sample and then using an ethanol extraction procedure to remove the linseed oil. A second set of X-ray measurements at identical locations in the same sample allowed the linseed oil to be indirectly mapped. An uneven distribution of linseed oil in the specimens with the lowest uptake (25% increase in weight) was seen as sharp gradients in the densitometry curves. With increased filling by the linseed oil, these gradients were gradually smoothed. Microstructural changes in specimens with high uptake were revealed using scanning electron microscopy. Through a combination of X-ray microdensitometry investigation and changes observed in the wood's mechanical properties and morphology, it was concluded that liquid flow during impregnation results in significant damage to the cell structure.     

Combined effect of wood moisture content,drill bit rotational speed and feed rate on drilling resistance measurements in Norway spruce (Picea abies (L.) Karst.)

ABSTRACT

An IML-RESI PD 400 drilling tool and a standard spade drill bit (IML System GmbH, Wiesloch, Germany) were used to study the combined effect of wood moisture content (MC), drill bit rotational speed and feed rate on drilling resistance (DR) and feeding force (FF). Tests were made with Norway spruce (Picea abies (L.) Karst.) conditioned in a normal climate (20°C/65% RH), at 20°C/95% RH, vacuum-pressure impregnated in water, and oven-dried. Rotational speeds and feed rates had an impact on feed rate per cutting edge for the major cutting edge of the drill bit which was used for correlation with DR and FF for various MC. Impact of MC on DR and FF depended on rotational speeds and feed rates of the drill bit. For feed rates per cutting edge less than 0.09?mm, DR was higher for water saturated (WS) specimens. Negligible differences between DR for various MC were found for feed rates per cutting edge between 0.09 and 0.15?mm. DR was higher at low MC for feed rates per cutting edge which were higher than 0.15?mm. FF extremely increased in conditioned (20°C/95% RH) and WS specimens at feed rates per cutting edge less than 0.1?mm.     

Effects of previous solvent exchange on acetylation of wood

Wood specimens were prepared in a swollen state using solvent exchange (PS) treatment. The swollen wood specimens were acetylated using acetic anhydride by heating at 80–120°C. At the beginning of heating, the weight percent gain (WPG) of PS-treated wood was greater than that of conventionally acetylated wood. This acceleration effect of the PS treatment was explained by the introduction of treating reagent into the wood polymers where the intermolecular hydrogen bonds were previously broken. On the other hand, the PS treatment had no influence on the final WPG and moisture sorption characteristics of acetylated wood. This indicated that the intrinsic reactivity of wood constituents was unaffected by the PS treatment. The acetylation of PS-treated wood produced greater bulking and slightly higher dimensional stability than that in the case of conventional acetylation at the same WPG. It was speculated that the expansion of cell lumina due to the PS treatment resulted in greater bulking on acetylation and lesser swelling of acetylated wood with moisture sorption.     

Dynamic water vapour sorption properties of wood treated with glutaraldehyde

The dynamic water vapour sorption properties of Scots pine (Pinus sylvestris L.) wood samples were studied to investigate the modifying effects of glutaraldehyde. Pine sapwood was treated with solutions of glutaraldehyde and a catalyst (magnesium chloride) to obtain weight per cent gains of 0.5, 8.6, 15.5, and 21.0%, respectively. The sorption behaviour of untreated and treated wood was measured using a Dynamic Vapour Sorption apparatus. The results showed considerable reduction in equilibrium moisture content of wood and the corresponding equilibrium time at each target relative humidity (RH) due to glutaraldehyde treatment. The moisture adsorption and desorption rates of modified and unmodified wood were generally faster in the low RH range (up to approximate 20%) than in the high range. Modification primarily reduced the adsorption and desorption rates over the high RH range of 20–95%. Glutaraldehyde modification resulted in a reduction in sorption hysteresis due to the loss of elasticity of cell walls.     

Impregnation of Norway spruce (Picea abies L. Karst.) wood by hydrophobic oil and dispersion patterns in different tissues

Wood from Norway spruce (Picea abies L. Karst.) is biologicallydegraded in exposed conditions. It also has anatomical featuresthat make it difficult to impregnate with preservatives by currentlyavailable industrial processes. In the study reported here,we used the new Linotech process to impregnate Norway sprucewood with hydrophobic linseed oil and then quantified its uptakeand dispersal in anatomically distinct wood tissues. We alsoinvestigated the effects of the wood moisture content on theresults of the impregnation. Samples (500 x 25 x 25 mm) weretaken from 15 trees in a coniferous forest in northern Sweden(64° 10' N, 160–320 m a.s.l.). The parameters forthe Linotech process were 2–3 h treatment time at 0.8–1.4MPa and 60–140°C. To determine the level of uptake,the linseed oil was extracted from the impregnated wood usingmethyl-tertiary-butyl-ether. The uptake was quantitatively analysedby comparing X-ray microdensitometry values obtained followingimpregnation both before and after oil removal. In earlywood,initial moisture content had an obvious effect on the impregnationresult. Six times more oil was taken up when the moisture contentwas greater than ~150 per cent than when it was less than 30per cent. Theoretical calculations, based on density levels,suggest that the water-filled porosity of the wood (water volumedivided by porosity volume) was positively correlated with thelinseed oil uptake, and more strongly correlated in earlywoodthan in latewood. There were also significant differences inuptake between different wood tissues; heartwood/mature woodand heartwood/juvenile wood showed 10–20 per cent weightincreases due to linseed oil uptake, compared with 30–50per cent in sapwood/mature wood. Examination by scanning electronmicroscopy confirmed these uptake patterns. The moisture contentafter impregnation was about 5 per cent, irrespective of theLinotech process parameters, tissue type and initial moisturecontent. In conclusion, the impregnation process used here resultsin high levels of well-dispersed linseed oil uptake and shouldfacilitate drying.     

Influence of wood planing on the second-order effects of moisture sorption in sugar maple

Summary Two types of machines, a conventional planer, and a fixed-knife pressure-bar planer were used to prepare matched specimens of sugar maple wood. After adsorption and desorption, both experiments at 21 °C, the EMC, swelling in all principal directions as well as compliance coefficient in radial compression were measured. Two specimen sizes were used for these expe‐riments. For a given equilibrium moisture content, tangential and radial dimensions were greater after desorption than after adsorption, as previously described. When equilibrium was reached by gaining moisture, the wood was stiffer in radial compression compared to when the equilibrium was reached after losing moisture. The magnitude of this phenomenon, second-order effects of moisture sorption, was slightly affected by the type of planing. These effects on swelling were greater for large specimens prepared by conventional planing compared to fixed-knife pressure-bar planing. Small specimens showed similar magnitudes of this phenomenon with both planing methods. No differences between planing methods were found for the radial compliance coefficient measured on either specimen size. Therefore, the second-order effects of moisture sorption appeared to be a bulk phenomenon and not restricted to the superficial layers of wood. Received 9 December 1997     

Data analysis of hyperspectral NIR image mosaics for the quantification of linseed oil impregnation in Scots pine wood

Eight pieces of sapwood and heartwood from Scots pine, before and after linseed oil impregnation, were used to make 16 near-infrared hyperspectral images (90–200 pixels wide × 466–985 pixels long × 239 wavelengths: 982–2,480 nm). The wood pieces were selected according to a 2 × 2 experimental design using radial–tangential cut and heartwood–sapwood as factors with two replicates. A first mosaic of 16 images was cleaned and analyzed by image principal component analysis. Interpretation was realized by studying score images and score plots by brushing interaction. In the resulting T1–T2 score plot, the untreated pieces formed a dense cluster, while the impregnated ones showed larger variation. The good separation of treated and impregnated clusters was confirmed by PLSDA showing low false negatives and positives. Analysis of the eight impregnated wood pieces clearly showed regions of wrong impregnation in one wood piece. Loadings resembling linseed oil spectra indicated that this was due to badly polymerized linseed oil. After removing the outlier piece, a new model was made on the seven-piece mosaic showing in the T1–T2 score plot that heartwood and sapwood absorbed the linseed oil differently. This difference was not detected in the untreated wood, so it had to come from the impregnation process. Edges reacted differently from surfaces to the impregnation process as seen in the T1–T4 score plot. These findings show that a future online quality inspection of both raw wood and impregnated pieces would be feasible.     

Hygroexpansion of wood during moisture adsorption and desorption processes

In order to investigate the shrinking and swelling behavior of wood at a non-equilibrium state, the moisture sorptlon processes of wood under constant and changing conditions were studied. For the static sorption experiment, Chinese fir （Cunninghamia lanceolata） specimens were subjected to the adsorption processes at 25℃, 10 different relative humidity environments and the moisture contents were measured at distinct time intervals of adsorption processes. For the dynamic sorption experiment, the specimens were exposed to periodically and linearly varying relative humidity between 45% and 75% at 25℃. Moisture content as well as radial and tangential dimensional changes in response to the changing relative humidity were measured. The main results from the experiments indicated that： the moisture sorption isotherms of Chinese fir at equilibrium state and different stages of adsorption processes could be characterized by S-shape curves. From the non-equilibrium state to the equilibrium state, the sigmoid moisture sorption isotherms changed from smooth, gradually increasing values to a steep rise at 100% humidity. Furthermore, under dynamic conditions with a constant temperature and a linearly and periodically varying relative humidity, the moisture content as well as radial and tangential dimensional changes of the specimens generally waved but lagged behind the relative humidity change.     

Influence of the pore structure of wood on moisture desorption at high relative humidities

Abstract

The influence of the porous structure on moisture desorption of two temperate and five tropical hardwoods was studied. Two experimental techniques were used to perform moisture desorption tests from full saturation at 25°C. The first one was the saturated salt solutions [between 33% and 90% relative humidity (RH)] and the second one was the pressure membrane method (above 96% RH). More emphasis was given to results obtained at high RH, given that sorption in that case is mainly governed by the capillary forces. The porous structure of these hardwoods was characterized by mercury intrusion porosimetry (MIP) and by quantitative anatomical analysis. The results showed that desorption of liquid water was very different among the hardwood species. The MIP technique appeared as an important tool to evaluate the fluid paths within wood, which permitted the prediction of water behavior in wood during drainage from full saturation at high RH. Quantitative anatomical results were very useful for explaining the first steps of drainage and mercury penetration in wood.     

Analysis of the water vapour sorption isotherms of thermally modified acacia and sesendok

Abstract

Two Malaysian hardwoods, acacia (Acacia mangium) and sesendok (Endospermum malaccense), that had been subjected to oleo-thermal modification were studied to determine their sorption isotherm behaviour using a dynamic vapour sorption apparatus. All the specimens were thermally modified using palm oil at three different temperatures (180, 200 and 220°C) and three different times (1, 2 and 3 h). The results showed that there was a reduction in equilibrium moisture content at each target relative humidity due to the heat treatment, but that the two wood species showed different behaviour in this respect. The adsorption isotherms were analysed using the Hailwood and Horrobin model, with excellent fits to the experimental data. The monolayer water and polylayer water were both reduced at a range of relative humidity values of the treated samples, although behaviour between the two wood species differed. Heat treatment resulted in an increase in hysteresis ratio, which was probably due to the increase in matrix stiffness of the cell walls.     

Effects of fire-retardant treatment and wood grain on three-dimensional changes of sandwich panels made from bubinga decorative veneer

ABSTRACT

The effects of a fire-retardant treatment (FRT) and wood grain on three-dimensional changes of aircraft sandwich panels were evaluated. Unvarnished and varnished panels having the outer decorative layer made with bubinga (Guibourtia spp.) were studied. Half of the samples from each type of panel received an FRT (phosphate-based) on all three layers of the decorative plywood. The other half had the two inner layers treated and the outer layer untreated. Three different figures formed by the rotary cutting and grain orientation were identified and separately studied on veneer surfaces. Samples pre-conditioned to 20°C and 40% relative humidity (RH) underwent an adsorption (25°C, 90% RH) and then a desorption (25°C, 40% RH) treatments. Changes in moisture content (MC), swelling, shrinkage, roughness, and waviness were measured after each moisture exposure condition. The results showed that the FRT increased significantly MC, swelling, and shrinkage of unvarnished and varnished panels. This treatment as well as the type of wood figure affected roughness and waviness variations of unvarnished panels. However, the effects of these two factors were not noticeable once panels were varnished.     

Note on radiation processed wood-plastic materials

Summary Specimens ofAbies sp. (fir),Pinus longifolia (chir),Vateria indica (vellapine),Dichopsis elliptica (pali) andMangifera indica (mango) were impregnated with monomers of styrene and methylmethacrylate and irradiated under different conditions. The treated specimens were tested as to their crushing strength, their bending strength and their water absorption. The results first indicate and increase in density due to impregnation. A reduction in moisture absorption and volumetric swelling as compared with untreated controls and increase in crushing strength were observed. The properties varied due to a non-uniform penetration of the polymer. Further experiments on the resistance against degradation by fungi were carried out and respective results are listed and discussed.     

Corrosion of metal fasteners embedded in acetylated and untreated wood at different moisture contents

ABSTRACT

Acetylated wood is now commercially available and designed to be used in certain outdoor applications as an alternative to preservative-treated wood. Fastener corrosion can be a concern in preservative treated wood when the wood remains wet for long periods. However, little data on the corrosiveness of acetylated wood exists beyond the product literature. Here we examine the corrosiveness of commercially obtained acetylated wood and compare it against unmodified (untreated) southern pine (Pinus spp.). Corrosion rates of plain carbon steel, hot dip galvanized steel, and stainless steel were calculated gravimetrically after a one year exposed in the wood. Four different moisture conditions were examined: 90% relative humidity (RH), 95% RH, 100% RH, and a fully water saturated condition. When compared to literature data on the corrosion of fasteners in preservative treated wood at 100% RH, the acetylated wood had much lower steel corrosion rates than all preservatives examined; the measured corrosion rates for galvanized steel were lower than all preservatives except chromated copper arsenate. These measured corrosion rates across a range of moisture conditions can be used to inform the selection of appropriate corrosion resistant fasteners when building with acetylated wood.     

Natural weathering of Scots pine (Pinus sylvestris L.) wood treated with epoxidized linseed oil and methyltriethoxysilane

In this study, the effect of natural weathering on the performance of Scots pine sapwood treated with epoxidized linseed oil (ELO) and methyltriethoxysilane (MTES) was investigated by measuring water uptake, colour, check propagation and chemical changes. Boards were impregnated in a pilot-scale autoclave under various conditions. After the treatments, pairs of samples were cut from the treated boards and exposed at 45° angle facing south for a long-term test of natural weathering above ground in Uppsala (Sweden). The effect of solar radiation and humidity on the colour changes, water uptake, check propagation and chemical alterations was assessed during 20 months of exposure. The obtained results can serve as indication for the viability of the treatments. Samples impregnated with low retentions of ELO showed similar performance regarding check propagation and moisture uptake as samples with higher retentions. No significant difference between these samples was found regarding colour change which is mainly caused by blue stain fungi on the surface. In opposite, samples treated with MTES exhibited no consistent water uptake and check propagation unproportioned to the applied retentions. The spectra of ELO- and MTES-treated wood after weathering showed a significant decrease of the peak at 1510 cm^?1 indicating delignification of wood surface caused by weathering.     

Assessment of hygroscopic conditioning performance of interior decorative materials IV: Sorption characteristics of wood under high relative humidity condition

The equilibrium moisture content (EMC) of six wood species under desorption conditions of 20°C and 100% 0% relative humidity (RH), and the rate of adsorption at various depths of three wood species blocks under 98% RH at 22.5°C were studied. There were no significant differences among the EMC values for these six wood species over the RH range 40% 0%, but there were highly significant differences over the RH range 100% 50% at constant 20°C. The amount of moisture absorbed in the wood decreased curvilinearly with the increase of depth in the specimens as sorption time increased, and their relation could be represented by a semilogarithmic equation. Time-dependent adsorption behavior at various depths of the wood specimens could be represented by an exponential equation as a function of the product of the difference between moisture contents at equilibrium and initial conditions and the term (1 – e^–t/). The value of of various wood species was found to increase linearly with the increased depth of the specimen and showed the following trend: hard maple (Acer sp.) > China fir (Cunninghamia lanceolata) > Japanese cedar (Cryptomeria japonica D. Don).Part of this report was presented at the 47th annual meeting of the Japan Wood Research Society, Kochi, April 1997.     

Introducing undeinked old newsprint as a new resource of electrical purposes paper

This work introduces, for the first time worldwide, undeinked recycled old newsprint as a new resource of electrical purposes paper. Impregnation of undeinked recycled old newsprint paper with linseed oil enhances the breaking length of paper and remarkably improves its electrical properties, i.e., the dielectric constant increases greatly and the a.c. conductivity decreases significantly due to impregnation. It was found that the electrical properties of the undeinked old newsprint paper and its linseed oil impregnated counterpart are close to the electrical properties of paper made from the more expensive virgin wood pulps and their linseed oil impregnated counterparts. Using the undeinked pulp is more privileged than using the deinked pulp; because eliminating the deinking step saves money, time, and reagents. In addition, eliminating the deinking step improved the breaking length of paper. Electron dispersive X-ray elemental analysis (EDX) was used to investigate the undeinked and deinked pulps for residual elements originating from the printing materials. EDX was correlated to the slight differences in electrical properties of paper made from undeinked and deinked pulps. However, impregnation was able to overcome these slight differences. It was shown that improvement in electrical properties, due to impregnation, is sustained at elevated temperatures.     

不同含水量球孢白僵菌孢子抗逆性研究

影响球孢白僵菌（Ｂｅａｕｖｅｒｉａｂａｓｉａｎａ（Ｂａｌｓ．）Ｖｕｉｌ．）的贮藏的环境稳定因素主要为环境温度及紫外光。孢子含水量高低影响虫生真菌菌株的耐热性,金龟子绿僵菌（Ｍｅｔａｒｈｉｚｉｕｍａｎｉｓｏｐｌａｅ（Ｓｏｒｏ．））在３０ｍｉｎ内的半致死...     

Wood surface stabilization with polyethyleneglycol,PEG

Summary The possibilities of interaction between wood, Pinus sylvestris, (60% RH) and potassium stained PEG 1500 (polyethyleneglycol) have been investigated using Scanning Electron Microscopy (EDS-analysis), dynamical mechanical techniques (DMTA) and X-ray diffraction (WAX).The EDS-analysis shows an even distribution of potassium in the cell wall. On the other hand the predicted cell wall swelling associated with PEG absorption is absent. This indicates that the method of staining PEG with potassium does not work. The DMTA-measurements show interaction on the molecular level between wood and PEG 1500. EDS-analysis, SEM- and WAX-investigations show free PEG in the impregnated specimens.     

Influence of moisture sorption history on the swelling of sugar maple wood and some tropical hardwoods

Summary Samples of nine tropical hardwoods from Peru and sugar maple wood from Quebec were selected to perform moisture sorption tests associated with swelling tests at 25 °C. The results demonstrate that, for a given equilibrium moisture content, tangential and radial dimensions, and hence the volume of wood, are greater after desorption than after adsorption. The importance of these differences, so-called second-order effects of moisture sorption, varied with the species and with the direction of swelling. These effects are proportionally greater in the tangential direction of wood than in its radial axis. Finally, two types of samples showed similar swellings for three equilibrium moisture contents.The author wishes to thank Professor M. Goulet for his support and help. This research was supported by the Canadian International Development Agency and the Natural Sciences and Engineering Research Council of Canada     

Effects of extraneous substances,wood density and interlocked grain on fiber saturation point of hardwoods

Abstract

Samples of nine tropical hardwoods from Peru and sugar maple wood from Quebec were selected for moisture sorption and swelling tests at 25°C. These tests evaluated the fiber saturation point (FSP) by two methods: following adsorption over distilled water, and from the volumetric swelling intersection point. Cold-water and hot-water extractives, sequential cyclohexane, acetone and methanol extracts, ash content, wood density and interlocked grain were also determined on matched samples. The results indicated that adsorption tests over distilled water were not applicable for determining FSP in all wood species. Condensation of water vapor apparently occurred, even though temperature during adsorption was controlled to the nearest 0.01°C. The volumetric swelling intersection point method was judged more appropriate. FSP ranged from 15 to 25% for tropical hardwoods and was 30% for sugar maple wood. FSP was negatively correlated with wood density, acetone extracted fraction, interlocked grain and ash content. These parameters each exerted similar effects on variability in FSP.