Fir Heartwood Research Articles

Revolutionizing wood permeability via microwave-initiated persulfate activation

Poor penetration of modifying reagents in wood due to the influence of extractives and pits in the wood. In this paper, microwave-activated sodium persulfate (MW-PS) solutions were used to remove extractives from fir heartwood and to disrupt pit membranes to improve the permeability of the liquid in wood. The large amount of energy generated by microwave irradiation decomposed S2O82- into SO4·-, while some of the resulting SO4·- combined with H2O to form·OH. The permeability of the liquid in the wood cells and cell wall interstices was increased by oxidative decomposition of the wood extractives by free radicals. The moisture in the wood absorbs the large amount of energy released by the microwaves, vaporizes and expands, destroying the pit membrane and creating new liquid channels. Microwave-activated persulfate-treated fir heartwood not only had a significantly lower extractive content (47.45%), but also an increased average pore size (91.84%). The most important thing is that the penetration of liquid into the fir heartwood was significantly increased (63.45%).

Study on the in-process measurements of the surface roughness of Douglas fir green veneers with the use of laser profilometer

The presented research concerns the use of a laser profilometer to measure the surface roughness of green Douglas fir heartwood veneers during the peeling process. It investigates the effect of various process parameters on the surface quality. Three experiments were carried out with a single variable factor for each experiment: log centration, soaking temperature and cutting speed. Moreover, the origin of the surface roughness of Douglas fir green veneers was investigated. The study shows that laser profilometer seems to be a useful equipment in online measurement of surface roughness of green veneers. Based on the experiment results it was stated that surface roughness of Douglas fir veneers is characterized by large differentiation depending on the location on the veneer. The performed analysis shows that the surface roughness of Douglas fir green veneer could be improved when using relatively high cutting speed, not too high steaming temperature and logs with a centered core. The presented study shows that the laser profilometer can be effectively applied to the measurement and evaluation of green veneers during the peeling process and that there is still an area to develop this methodology.

Colour Stabilization of Oak, Spruce, Larch and Douglas Fir Heartwood Treated with Mixtures of Nanoparticle Dispersions and UV-Stabilizers after Exposure to UV and VIS-Radiation.

Colour changes and associated wood degradation in exterior and interior applications influenced by ultraviolet (UV) and visible radiation (VIS) decreases the aesthetic value of the products and shortens the overall life of transparent coatings. The aim of the paper is to achieve colour stabilization of oak, larch, Douglas fir and spruce heartwood via surface treatment with UV stabilizers, hindered amine light stabilizers (HALS), nanoparticles TiO2, ZnO, and mixtures thereof, during exposure to UV and VIS radiation. Colour changes were evaluated during accelerated artificial ageing testing in Xenotest. The distinctly individual character of colour changes in surface treatments due to the underlying wood species was confirmed. A synergistic effect was found when using a combination of active substances compared to substances used individually. The mixture of benzotriazoles with HALS (Tinuvin 5151) in combination with TiO2 and ZnO nanoparticles was confirmed as one of the most effective treatments for colour stabilization of wood due to UV and VIS spectrums.

Transport of Polar and Nonpolar Liquids in Softwood Imaged by Neutron Radiography

The influence of the moisture capacity of cell walls on liquid transport in wood is studied using neutron imaging in combination with precision weighing. The time-dependent and spatial distribution of two liquids, one polar, water, and one nonpolar, decane, is documented during liquid uptake in the three orthotropic directions for samples of three softwood species: spruce and fir heartwood, and pine sapwood. Polar and nonpolar liquid uptake versus time is compared, the spatial distribution of the liquids within the samples is discussed, and the liquid volume and swelling profiles along the height of the samples are described in details. Water uptake is shown to be slower than decane uptake, due to water being adsorbed by the cells walls. Decane, due to its very low contact angle and high wettability compared to water, does not face much resistance from wood cellular features.

Near-infrared spectroscopy as a potential quality assurance tool for the wood preservation industry

Preservatives are used to extend the service life of wood used in situations where it is vulnerable to biodegradation. Wood preservation standards typically specify quality assurance procedures to differentiate heartwood and sapwood and to measure preservative loading and penetration. For spruce and hem–fir there are no reliable chemical spot tests to differentiate sapwood and heartwood. This makes it more difficult for these species to meet penetration requirements. For many of the recently introduced carbon-based preservatives, the only methods available to determine penetration involve detecting a surrogate in the formulation, or only some of the active ingredients. Multivariate models based on near-infrared spectroscopy (NIRS) have been used to predict a wide range of wood properties over the past 20 years. The present research evaluates the potential use of NIRS-based models as quality assurance tools for the wood preservation industry. Models were developed to differentiate hemlock and amabilis fir sapwood and heartwood. NIRS-based models were also able to differentiate untreated wood from wood treated with DDACarbonate and wood treated with tebuconazole. Models developed to predict DDACarbonate and tebuconazole retention were moderately accurate, but likely not precise enough to replace current quantitative assays.

Effect of compression on hydroscopicity of extracted Chinese fir heartwood

In order to clarify the effects of extraction and compression on the hydroscopicity of wood, Chinese fir (Cunninghamia lanceolata Hook.) heartwood samples with or without extraction were radially or tangentially compressed under water-saturated condition at room temperature. Warm water and 1% sodium hydroxide were used as different solutions for extraction. Water absorption capacity and moisture adsorption isotherms of the compressed samples were then tested. The fractal dimension of internal wood surfaces (D fs) was calculated based on adsorption isotherms by FHH equation. Results showed that in both compressed groups, the hydroscopicity of samples extracted by sodium hydroxide solution improved greatly, while that of samples extracted by warm water changed little, compared with that of water-saturated samples. Recovery of set and the change of hydroscopic environment inside wood were main reasons for the difference of water absorption among water-saturated samples and samples extracted with warm water and sodium hydroxide solution. The swelling rate of samples extracted by sodium hydroxide solution significantly increased. Moreover, the swelling rate in the tangential direction of tangentially compressed samples was obviously higher than that in radial direction of radially compressed ones. D fs values of woods extracted by warm water and sodium hydroxide solution decreased by 0.002 and 0.007 in a radially compressed group and by 0.013 and 0.013 in a tangentially compressed group, compared to those of water-saturated one. Therefore, the conclusion can be made that the extraction and compression treatments used in this study have no obvious effects on internal wood surface.

Influence of wood moisture content and wood temperature on fungal decay in the field: observations in different micro-climates

In this study, Scots pine sapwood (Pinus sylvestris L.) and Douglas fir heartwood (Pseudotsuga menziesii Franco) specimens were exposed in double layer field trials at four different exposure sites and under different exposure conditions (in total ten test sets). The material climate of wood in terms of wood moisture content (MC) and wood temperature was automatically monitored over a period of 6 years and compared with the progress of decay. The aim of this study was to highlight the interrelationship between microclimate, material climate, and decay as a basis for the establishment of dose-response functions to be used for service life prediction of wood and wood-based products. Differences in resulting decay dynamics between the test sites as well as between the different types of exposure were quantified and discussed with respect to corresponding microclimatic and material climatic conditions. The time between the beginning of exposure and the first occurrence of visible decay varied between the sites and influenced the total decay development. The fundamental importance of direct decay factors, such as MC and wood temperature, were underlined and basic requirements for establishing dose-response-functions to be used in service life prediction models were derived.

Dose–response relationships between wood moisture content, wood temperature and fungal decay determined for 23 European field test sites

Scots pine sapwood (Pinus sylvestris L.) and Douglas fir heartwood (Pseudotsuga menziesii Franco) specimens were exposed in double layer field trials at 23 different European test sites under different exposure conditions (in total 27 test sets). The material climate in terms of wood moisture content (MC) and wood temperature was automatically monitored over a period of up to 7 years and compared with the progress of decay. The overall aim of this study was to establish dose–response relationships between climate factors and decay as a basis for the service life prediction of wood. The “Scheffer Climate Index” based on weather data collected at official meteorological stations at the different test sites poorly correlated with the corresponding decay progress and was therefore not a suitable tool for estimating site-specific decay potential. In contrast, the use of the combined material climatic parameters MC and wood temperature led to a feasible dose–response function and turned out to be a useful basis for service life prediction of wood.

Effect of different drying methods on liquid penetration of Chinese fir plantation wood

Chinese fir plantation sapwood and heartwood boards were treated by three drying methods: radio frequency-vacuum drying (RFVD), conventional kiln drying (KD) and high temperature drying (HTD). The maximum amount of dyeing solution uptake by the capillary rising method was used to evaluate the liquid penetration of the treated wood. The pit aspiration ratio was determined by a semithin section method. Changes in wood microstructure were investigated using scanning electron microscopy. The results show that liquid penetration of Chinese fir sapwood after RFVD is significantly higher than that after KD and HTD. Liquid penetration of Chinese fir heartwood after RFVD is higher than that after HTD. Liquid penetration of Chinese fir sapwood is significantly higher than that of heartwood after three drying treatments. Low pit aspiration ratio and cracks of some bordered pits are the main reasons for the increase in liquid penetration after RFVD treatment.

Developing Diffusion Coefficients for SCF Impregnation of Douglas Fir Heartwood with Cyproconazole

The effects of the treating period and specimen length on supercritical fluid impregnation of cyproconazole were investigated for Douglas fir heartwood using cooling to induce biocide deposition. Retention levels at various treatment periods and locations were measured. These retention values were assumed to be equivalent to the concentration of biocide at the end of the treatment period. The concentration values versus distance from the surface were then fitted to an empirical expression as a function of time and distance. From the resultant concentration formulae, time‐varying effective diffusion coefficients for the biocide at the depth locations of the data were determined using Egner's solution method for the Fickian diffusion equation in one direction. The diffusion coefficient values suggested that diffusion was probably the rate‐limiting phenomena accounting for biocide penetration. Prolonged treatment appeared to increase the effective diffusion coefficients, probably by removing extractives in heartwood pits.

S�cheresse � coeur du Douglas et aptitude au d�roulage : recherche de proc�d�s alternatifs d'�tuvage. I. R�partition de l'eau dans le bois vert et r�humidification sous autoclave

Heart dryness of Douglas fir and ability to rotary cutting: Research of alternative boiling processes. I. Moisture content distribution inside green wood and water impregnation with an autoclave. The analysis of the moisture content varia- tions along Douglas fir increment cores, fresh cut logs and peeled veneers allowed to confirm the low level of moisture content inside Douglas fir heartwood. Whatever the tree and the inside ring location may be, the heartwood moisture content is about 30% vs. 80 to 150% for sapwood. Several hygrothermic treatments (conventional boiling, hot/cold baths, vacuum/pressure cycles) have been applied to 12 cm long bolts in view to measure the moisture content increasing. Only the treatments involving vacuum and pressu re appeared efficient. The heartwood moisture content after such treatments ranged from 50% to 150%. The higher M.C. were obtained inside earlywood. wood / Douglas / rotary cutting / heartwood / boiling proces

Optimization of Steam Explosion to Enhance Hemicellulose Recovery and Enzymatic Hydrolysis of Cellulose in Softwoods

A combination of Douglas fir heartwood and sapwood chips were steam pretreated under three conditions as measured by the Severity Factor (log Ro), which incorporated the time, temperature/pressure of pretreatment. By adjusting the steam pretreatment conditions, it was hoped to recover the majority of the hemicellulose component as monomers in the water-soluble stream, while providing a cellulosic-rich, water-insoluble fraction that could be readily hydrolyzed by cellulases. These three conditions were chosen to represent either high hemicellulose sugar recovery (low severity [L], log Ro=3.08), high-enzyme hydrolyzability of the cellulosic component (high severity [H], log Ro=4.21), and a compromise between the two conditions (medium severity [M], log Ro=3.45). The medium-severity pretreatment conditions (195°C, 4.5 min, 4.5% SO2 logRo=3.45) gave the best compromise in terms of relatively high hemicellulose recovery after stream pretreatment and the subsequent efficiency of enzymatic hydrolysis of the water-insoluble cellulosic fraction. The percent recovery of the original hemicellulose in the water-soluble fraction dropped significantly when the severity was increased (L-76.8%, M-64.7%, and H-37.5%). However, the ease of enzymatic hydrolysis of the cellulose-rich, water-insoluble fraction increased with increasing severity (L-24%, M-86.6%, and H-97.9%). Although more severe pretreatment conditions provided optimum hydrolysis of the cellulosic component, less severe conditions resulted in better recovery of the combined hemicellulose and cellulosic components.

Polyphenols and Colour of Douglas Fir Heartwood

Heartwood Colour Dihydroquercetin Leucocyanidin Summary The natural red-orange colour of Douglas fir heartwood limits its utilization for the production of thermo-mechanical pulps. Heartwood colour, determined in the CIEL*a*b* system, is studied in relation to various treatments applied to the wood. Heartwood differs from sapwood by the presence of poorly extractible pigments, fairly resistant to hydrogen peroxide bleaching. A model experiment suggests that they are formed by the enzymic reduction of dihydroquerce tin, the main extractive of Douglas-fir heartwood. The resulting unstable leucocyanidin spontaneously auto-oxidizes to polymeric pigments similar to those found in heartwood.

Unsteady-State Diffusion of Methanol in Douglas-fir Heartwood at High Temperatures

The unsteady-state diffusion of methanol in the tangential direction of water saturated Douglas fir heartwood was studied in an experimental analysis cell at temperature of 90, 120 and 150°C. Concentration profiles of methanol in wood were obtained for times between 30 and 480 minutes and sample thicknesses of 10 and 15 mm. From the measured concentration profiles, diffusion coefficients were calculated using a special form of Fick's second law which takes into account changes in the methanol concentration at the boundary layer. The measured diffusion coefficients of methanol in Douglas fir lie between 1.115*10 -9 and 1.755*10 -9 m 2 s -1 , increasing with temperature. Data of the same order of magnitude are found as diffusion coefficients for alkaline solutions in Kraft pulping. The resistance of the wood to the diffusion of methanol, expressed as the relative diffusion coefficients is inversely proportional to the temperature. This might be attributed to increased permeability of the cell wall by softening of the lignin or opening of aspirated pits. A deviation of Ficks second law was found at low methanol concentrations. The activation energy of the diffusion process was calculated to he 9.8 kJ mole -1 .

Summative Analysis of Nine Common North American Woods

Abstract The summative analysis of lignocellulosic materials has heretofore been a complicated process or the analysis has been incomplete. The Bomb/HPLC summative analysis method presented in this report results in a complete analysis of woody materials using a sample preparation scheme that is easily adopted into a normal laboratory routine. The method relies on HPLC for the majority of the component analyses. To demonstrate the applicability and reproducibility of the Bomb/HPLC method, ten wood samples, from nine different wood species, were analyzed in triplicate and the summative analysis of each sample was effected. The ten woods analyzed were: American beech ( Fagus grandifolia ), Quaking aspen ( Populus tremuloides ), Black cherry ( Prunus serotina ), Sugar (Hard) maple ( Acer saccharum ), Red (Soft) maple ( Acer rubrum ). White ash ( Fraxinus americana ), Yellow birch ( Betula verrucosa ), Douglas fir heartwood and Douglas fir sapwood ( Pseudotsuga menziesii ), and White fir sapwood ( Abies conco...

In Situ Observations on the Influence of Wood Moisture Content and Temperature on Spore Germination and Wood Colonization byPoria carbonica

A method for observing germinating fungal spores on wood was developed in which temperature and wood moisture content could be easily controlled and subsequent wood colonization could be determined. Thin radial sections of Douglas fir (Pseudotsuga menziesii) heartwood (8 mm x 8 mm x 60 mu m) were inoculated with a spore suspension and a similar wood section was placed over the inoculated section forming a ''spore sandwich''. The ''spore sandwiches'' were incubated between larger blocks of Douglas fir heartwood to maintain control of the wood moisture content during incubation in controlled temperature-humidity chambers. Spore germination was observed by opening the ''spore sandwiches'' and staining the spores in situ for microscopic observation. Wood colonization was determined by isolations from the surrounding wood blocks. The ''spore sandwich'' method was used to study the influences of temperature and wood moisture content on spore germination of Poria carbonica. Basidiospores and asexual spores germinated and colonized wood at and above the fibre saturation point (c 30% moisture content), but not below. Both spore types germinated and colonized wood at 22 and 30 degrees Centigrade, but basidiospores failed to germinate at 5 and 35 degrees, whereas asexual spores germinated at 5 and 35 degrees, butmore » were unable to colonize the wood. The ''spore sandwich'' method provides a means for assessing spore germination and wood colonization by wood decaying fungi under conditions simulating those occurring naturally in wood in service. (Refs. 21).« less

Organic compounds in cold-water extracts of grand fir heartwood

Cold-water extractives of grand fir, Abies grandis (Dougl.) Lindl., heartwood yielded pinitol, sequoyitol, and a compound containing a ketone group. No other organic chemicals were extracted.

THE INITIATION AND SPREAD OF PORIA WEIRII ROOT ROT OF DOUGLAS FIR

Root rot caused by Poria weirii Murr. occurred when healthy roots of Douglas fir came into contact with inoculum in infected roots of the previous stand. Mycelium grew ectotrophically on the bark of the Douglas fir roots, frequently well in advance of growth in the wood, and penetrated to living tissues directly through sound as well as injured bark. Spread of the disease to adjacent trees took place where healthy and diseased roots were in contact, the mycelium apparently spreading to only a very limited extent through natural soil. It was shown that mycelium could invade roots of trees felled for at least 12 months and Douglas fir heartwood that had been buried in soil for at least 12 months. Viable Poria mycelium was isolated from infected roots as small as 2 cm in diameter 11 years after the trees had been cut. While Douglas fir and western hemlock appeared to be quite susceptible to infection, western red cedar, red alder, and bigleaf maple showed considerable resistance.

THE ANTIPULPING EFFCT OF THE FLAVANONE OF THE LARCH HEARTWOOD IN SULPHITE COOK

J. C. Pew (1949) had isolated a crystalline compound, the 3, 3', 4', 5, 7-pentahydroxyflavanone, from the heartwood of Douglas fir, and recognized that owing to the presence of the flavanone the wood is hardly pulped by the sulphite cook. Recently Hasegawa (1951) has identified the flavanone of the larch heartwood with that of the Douglas fir heartwood. In this paper, the antipulping effect of the flavanone of the larch heartwood in the sulphite cook was examined.The sulphite cooks were carried out on the following samples ; four kinds of the heartwood in which content of the flavanone varied, the larch heartwood extracted methanol (the flavanone is soluble in methanol), the spruce wood, the spruce wood impregnated with the flavanone and with some compounds related to the chemical structure of the flavanone such as pyrocatechol, resorcin, phloroglucin and meconic acid.results of cooks indicate that the flavanone has the antipulping effect in the sulphite of the larch heartwood.