Your search resulted in 90 documents. Displaying 25 entries per page.
Elucidation of reactive sites of wood modified with acetic anhydride: Insights from density functional theory calculations
2020 - IRG/WP 20-40892
Density functional theory (DFT) was employed to investigate the interaction of cellulose and lignin with acetic anhydride for explaining the wood modification process. Atoms in molecules (AIM) and reduced density gradient (RDG) along with non-covalent interaction (NCI) plots were used to analyse the intermolecular bonding characteristics. Cellulose was modelled with a cellobiose unit (dimer of glucose) and dibenzodioxocin was used to represent lignin model. This typical lignin model has three predominant linkages such as β-O-4, α-O-4 and 5-5’. All DFT calculations were performed at dispersion-corrected wB97X-D/6-311g(d,p) level of theory. The obtained results revealed that interaction energy of cellobiose-acetic anhydride was higher (about 20 kJ mol-1) than lignin-acetic anhydride. Structural analysis demonstrated that acetic anhydride undergoes a conformational change in lignin-acetic anhydride conformer to avoid steric repulsion from lignin aromatic moieties. Hydrogen bonds are studied to provide detailed information about strength of the interaction between cellobiose/lignin and acetic anhydride using AIM, RDG and NCI. The results showed that H-bond between cellobiose-acetic anhydride is stronger than lignin-acetic anhydride, and those H-bonds have a non-covalent character. It is observed from AIM analysis that electron density and its Laplacian for cellobiose-acetic anhydride is two-fold higher than lignin-acetic anhydride. A similar result was found in RDG analysis, and the calculated eigen value from electron density is more negative for cellulose-acetic anhydride case. This work suggested that acetic anhydride strongly bound to cellobiose during acetylation of wood rather than lignin model, and the detailed investigated data provides the interaction mechanism of acetic anhydride treatment of wood to some extent.
V Ponnuchamy, A Sandak, J Sandak, R Herrera Diaz
The effects of density on vertical variation of permeability of Sitka spruce within tree
2000 - IRG/WP 00-40156
Tree improvement of Sitka spruce is a combination of silviculture and tree breeding aimed at producing higher quality products including increased growth rate and timber yield, and wood density. It is useful to know annual ring structure and density distribution when studying the quality of wood, grading it, or determining how the wood structure affects residual flow in softwoods. Since density is a factor under genetic control, the study in this article details the effects of density on longitudinal and radial permeability of Sitka spruce from base to apex. Comparison of overall means of both longitudinal and radial void volume filled (%) suggest that longitudinal permeabilities were almost the mirror image of those for the radial permeability along the tree trunk.
Implications for comparability of laboratory experiments revealed in studies on the variability in survival and wood consumption between colonies of Coptotermes acinaciformis (Froggatt) (Isoptera: Rhinotermitidae
1983 - IRG/WP 1196
(Summary of paper 1193) Groups of Coptotermes acinaciformis, originating from six colonies, three taken from each of two localities, 1500 km apart, in northern Australia (Townsville, Darwin) were kept at population densities of 0.005, 0.01 and 0.02 g termites/mL. Survival and wood consumption of the groups after 8 weeks followed a similar pattern in the colonies from both collection areas. Groups were least vigorous at the lowest population density; their performance reached a maximum at a population density of 0.01 g/mL. The subsequent decline in vigour was less marked as the highest population density was approached. However, the actual values for survival and wood consumption varied widely between colonies, irrespective of their origin. It is recommended that in all laboratory experiments which use survival and wood consumption as indicators of termite vigour, controls of a favourable as well as an unfavourable food type are included which would serve to monitor the vigour of the termites. Results from termite sources whose vigour falls below a certain threshold value would have to be treated with caution and could not be used in definative data, as e.g. in defining critical retentions of wood preservatives.
The Pilodyn instrument as a non-destructive tester of the shock resistance of wood
1978 - IRG/WP 2107
A new non-destructive shock resistance tester, the PILODYN, has been developed. The instrument measures the fracture surface area created by a constant amount of energy. It operates by shooting a blunt pin into wood by an exact amount of energy. The penetration depth is read on a scale. A wide field of application is open to a non-destructive shock resistance tester such as: 1) assessment of the residual strength of poles decaying from the outside; 2) laboratory evaluation of biodeteriorated wood; 3) the state of wood foundations and woody pilework; 4) degree of chemical decomposition of wood; 5) degree of thermal decomposition of wood; 6) measurement of the density (strength) of standing trees; 7) measurement of the density (strength) of sawn timber; 8) production control of wood based panel boards. A review of existing test results as well as new results are presented containing items 1, 6 and 7. An evaluation of the potential of the PILODYN is attempted.
A standardised procedure for the treatment of timber with test chemicals
1986 - IRG/WP 2257
A procedure is described which allows the standardisation of sample handling and data manipulation during trials invastigating the treatability of timber with test chemicals. The use of computer software allows the data to be handled efficiently.
J Norton, A Zosars, L E Leightley
Natural resistance of twenty-six Guianese wood species against marine borers
1988 - IRG/WP 4144
This note is a contribution on the study of the natural resistance of some wood species from French Guiana, some of which could be found too in the neighbourhood. Here are presented the results after one year exposure in the marine environment.
L N Trong
Absorption of inorganic salts solutions. Retentions of inorganic salts. Fire retardants
1990 - IRG/WP 3625
The study aims evaluated the impregnation capacity using fire retardants on woods with differents densities. At the same time, impregnation with several fire retardant salts were carried out in order to obtain their absortion and retention in wood.
A Garcia, J Navarro
A summary of tests and practical experiences with the Pilodyn wood testing instrument
1980 - IRG/WP 282
This paper presents a summary of the reports, tests and practical experiences with the Pilodyn wood tester not only, however, concerning poles but also in other fields such as standing trees, sawn timber etc. The principle of the Pilodyn is a spring-loaded pin which is fired into the object and the depth to which the pin penetrates is correlated to physical and mechanical properties of the object.
Some relationship between physical characteristics and treatability of Bolivian woods
1987 - IRG/WP 3434
Using the available data on physical characteristics of 25 Bolivian woods, some relationships between porosity, specific gravity and treatability (hot and cold open tank process with 5% pentachlorophenol) were analysed. The aim of this report is to give information on technical characteristics of Bolivian hardwoods which have been studied in this country by Centro de Desarrollo Forestal and in Peru by Junta del Acuerdo de Cartagena.
A S Viscarra
Ancillary properties of vapor boron-treated composites
2001 - IRG/WP 01-40210
This paper discusses the water absorption, thickness swelling, and internal bond strength of North American composites treated using a vapor boron treatment process. For oriented strandboard, high boron loadings led to lower internal bond strength and lower thickness swelling. Water absorption results were variable but no deleterious effect of treatment was noted. For medium density fiberboard, the highest loadings led to reduced internal bond strength. Thickness swelling decreased with increasing boron level, but not significantly. As with OSB, water absorption results varied.
W A Jones, H M Barnes, R J Murphy
Methods for testing fumigant efficacies against termites
1986 - IRG/WP 1297
Methodologies for testing fumigants against termites are reviewed and factors needed to be taken under consideration for standardization listed. Toxicity should be defined by both direct exposure to the gas and under more practical "barrier" conditions which include test enclosures simulating abiotic surroundings of the termites, i.e. wood, nest material, etc. To observe latent effects, mortality should be recorded periodically after exposure until rates decrease to control levels. Fumigant efficacy should be reported as a function of concentration and exposure time, termed lethal accumulated dose (LAD).
N-Y Su, R H Scheffrahn
Treating Eucalyptus tereticornis wood with boron: Optimizing treatment conditions
2005 - IRG/WP 05-40309
Even though Eucalyptus tereticornis wood is suitable for small timber purposes, being non-durable, it needs to be treated with preservative chemicals. As it is a heavy, hard and difficult to treat species, the possibility of using diffusible boron compounds was investigated. The present study explored the effect of impregnation conditions such as treatment schedule, concentration of treatment solution and the moisture content of wood on the achievement of desired dry salt retention (DSR) of the preservative in the treated wood by conducting a commercial scale trial. The study revealed that wood density and moisture content adversely affected the boron impregnation. It was clear that even E. tereticornis wood in green condition could be effectively boron impregnated using appropriate treatment schedule. Only long duration treatment schedules were found to yield the desired DSR levels. A solution concentration of 8% boric acid equivalent (BAE) was found to be required. Application of an initial vacuum of 760 mm Hg (- 85 kPa) for 15 minutes followed by a pressure of 1300 kPa for a minimum period of 60 minutes and a final vacuum of 760 mm Hg(- 85 kPa) for 5 minutes was found to be an appropriate treatment schedule.
T K Dhamodaran, R Gnanaharan
Effect of incising depth and density on treatment of Douglas fir, hem fir and spruce-pine-fir lumber with CCA, ACZA or ACQ
1997 - IRG/WP 97-40093
Incising markedly improves both the depth and uniformity of preservative treatment of refractory wood species, but there are few studies directly comparing the effects of incising depth and density on penetration and retention of commonly used waterborne preservatives in wood species from the western United States. The effects of two incision densities (7300 and 8900 incisions/square meter) at two depths (5 and 7 mm) were investigated using two strength classes of Douglas fir, hem fir and spruce-pine-fir lumber. In general, grade or strength class had no significant effect on treatability. Treatability markedly improved with increasing incision depth, while increased incision density produced less tangible results. Ammonia-based treatments were associated with deeper penetration reflecting the ability of the heat and/or ammonia to improve preservative penetration. Further studies are underway to evaluate the effects of incising and subsequent preservative treatment on strength properties.
M Anderson, J J Morrell, J E Winandy
Examination of the Pilodyn as a non-destructive test method for detecting decay in CCA treated eucalypt poles
1982 - IRG/WP 2177
Below groundline condition of 274 CCA treated eucalypt poles comprising 13 different species was examined using 6 and 12 Joule Pilodyn units with 2 and 2.5 mm diameter pins. The data obtained was used to calculate regressions of density on pin penetration. A decrease in density was accompanied by an increase in pin penetration. The best correlation was found using the 6 Joule, 60 x 2.5 mm² diameter pin. The results are discussed with comments on future work with the Pilodyn.
L E Leightley
A study of wood quality of Juglans nigra and hybrid walnut (MJ 209xRA) : durability against Coriolus versicolor, density and MOR
2004 - IRG/WP 04-10522
The study investigated possible effects of harvesting season on some wood properties of Juglan nigra (JN) and a hybrid walnut (MJ209xRA). The samples were taken from trees which were harvested in June July, August, November of the same year, and March in the year after to determine whether there were any significant differences in wood properties as regards the harvesting seasons. In order to test the durability of the 648 wood samples white rot fungus Coriolus versicolor challenge test (EN113 (AFNOR 1994) was applied by using agar culture medium. The bending strength was also determined after a sixteen-week exposure to the above mentioned fungus. The data obtained clearly indicated that the heartwood of JN was more durable than its sapwood. JN sapwood was more durable than MJ209xRA sapwood. The same trend was observed with the Modulus of rupture (MOR : EN 310): the heartwood displayed higher MOR value than the sapwood. Wood density measurements also demonstrated that the wood density values of the sample heartwoods were much higher than those of the sapwoods. Results also illustrated that, from the wood durability point of view, March is the least interesting period for harvesting. June and November, on the other hand, proved to be more favourable periods as regards harvesting. This study clearly indicates that the durability and the strength of the hybrid walnut (MJ209xRA) are lower than those of the walnut (Juglans nigra), and this fact should be considered in the exploitation of hybrid wood.
B Charrier, F Charrier, D P Kamdem, J B Aurel, G Janin
Comparative study on physical properties of four fast growing timber species of Bangladesh
2006 - IRG/WP 06-10570
Ghoraneem (Melia azedarach), Rain tree (Albizia saman), Sissoo (Dalbergia sissoo Roxb.) and Akashmoni (Acacia auriculiformis) plantations are started as a fast growing timber specie from a few years back in Bangladesh. Initian objectives were to get fuel wood only from those trees, but a very positive response was found for Ghoraneem, Rain Tree, Sissoo and Akashmoni timber in the users market by cutting the trees and therefore maintaining its rotation period. The timber of these trees also attracted the furniture makers as well as general users due to its grain, texture, colour, availability and low-cost which helped to boost the commercial value of the species. This popularity and high demand of Ghoraneem, Rain Tree, Sissoo and Akashmoni timber in the market encouraged to carry out a comparative study on the physical properties of these fast growing species. The wood samples from three different heights for every individual test have been collected and their respective physical properties such as shrinkage, density and moisture content were examined to make a comparison. Ghoraneem, Rain Tree, Sissoo and Akashmoni trees showed significant difference in respect of tangential and radial shrinkage, respectively. Rain tree showed the lowest volumetric shrinkage (7,517%) and Akashmoni the highest (13,66%). Tangential, radial and longitudinal shrinkage didn’t differ significantly among the top, middle and bottom sections of a particular quality of wood. Density also differed significantly among the species. Sissoo showed the highest density (0.74 g/cm3) when compared to the others.
M M Islam, B K Dey, M O Hannan, G N M Ilias
Dip-diffusion of dressed timber - Effect of drying
1989 - IRG/WP 3509
The effect of drying on dip-diffused dressed freshly sawn timber was determined by the depth of penetration of boron achieved on the two test timber species, White cheesewood (Alstonia scholaris) and Light Hopea (Hopea papuana). The results obtained showed that light density White cheesewood was completely penetrated even after 3 days drying while Light hopea, treated immediately achieved 5.2 mm penetration after 2 days diffusion and subsequently better after 14 and 21 days diffusion. Adequate penetration was only achieved after 14 and 21 days diffusion when there was delay between 30 minutes and 72 hours.
H C Konabe
Evaluating the natural durability of native and tropical wood species against Reticulitermes flavip
2004 - IRG/WP 04-10539
Environmental pressures to eliminate arsenate from wood preservatives has resulted in voluntary removal of CCA for residential applications in the United States. A new generation of copper organic preservatives has been formulated to replace CCA for decking and in-ground applications but there is no guarantee that these preservatives represent a permanent solution to all related problems. Therefore, it is still necessary to evaluate alternative treatments, as well as naturally durable wood species, in order to be prepared for future changes in the field. In this study, six hardwoods and six softwoods have been evaluated for their ability to resist termite damage by Reticulitermes flavipes in a 4-week laboratory no-choice test. In addition, moderately resistant Douglas-fir and southern pine wood blocks were evaluated after treatment with copper borate, copper naphthanate, and N,N-naphthaloylhydroxylamine (NHA). Erisma, juniper, ipe and white-cedar were shown to be highly resistant. NHA protected Douglas-fir and southern pine as effectively as copper borate or copper naphthanate. These results suggest that some naturally durable wood species, both tropical and native, can inhibit R. flavipes as effectively as preservative treatment.
R A Arango, F Green III, K Hintz, R B Miller
MDF manufactured from blends of cypress pine and radiata pine shows enhanced resistance to subterranean termite attack
2001 - IRG/WP 01-40214
Medium density fibreboards consisting of blends of the naturally durable wood species white cypress pine (Callitris glaucophylla) and non-durable wood species were manufactured in a commercial plant and subjected to a bioassay using the subterranean termite species, Coptotermes lacteus. A board composed of 30% cypress pine, 30% slash pine (Pinus elliottii) and 40% of the naturally durable hardwood species spotted gum (Corymbia maculata) was also manufactured and bioassayed against C. lacteus. The aims were to determine (i) whether boards containing cypress pine possessed increased resistance to termite attack compared to a control manufactured entirely from non-durable wood species; (ii) the relationship between the cypress pine content of boards and their resistance (if any) to termite attack; (iii) whether the termite resistance of boards containing cypress pine could be further enhanced by the addition of spotted gum fibre. There was an inverse relationship between the cypress pine content of MDF specimens and mass losses of the specimens during the bioassay, the percentage mass losses of specimens containing 11.4, 16.2 and 34.2% cypress pine being 20.3, 13.4 and 8.8%, respectively, compared to 32.8% for the control, which consisted of non-durable slash pine (80%) and hoop pine (Araucaria cunninghamii) (20%) fibre. There was strong evidence that the inverse relationship between the cypress pine content of boards and mass losses during the bioassay was linear, although a statistically significant quadratic (curvilinear) effect was also apparent. The addition of spotted gum fibre to boards did not increase their resistance to termite attack. Cypress pine heartwood contains a variety of extractives that are either toxic or repellent to termites, and the increased termite resistance of MDF containing cypress pine compared to the control is probably due to the insecticidal effect of such chemicals on C. lacteus. The incorporation of cypress pine fibre into MDF shows promise as an alternative to chemical biocides for increasing the resistance of MDF to termites. However, the response of termites to heartwood extractives varies between species, and therefore further experimentation is needed to test the resistance of MDF containing cypress pine fibre to attack by greater range of wood destroying termites under test conditions that more closely simulate field conditions.
P D Evans, S Dimitriades, C Donnelly, R B Cunningham
Effects of seed origin and site on both wood density and longitudinal fluid uptake of Sitka spruce (Picea sitchensis (Bong.) Carr.) with height in the tree grown in the United Kingdom
2002 - IRG/WP 02-40226
The variation in density and longitudinal fluid uptake was investigated in short specimens of wood taken from eight seed origins of Sitka spruce trees grown at two sites in the UK. Five trees of each seed origin at each site were sampled at three heights (1, 2 and 3 m above ground level). The density of the samples decreased with increasing height within the stem. This corresponded with increasing ring width. The change of the longitudinal fluid uptake from base to apex showed an inverse trend to density. Site had an effect on density and increased density reduced fluid uptake. Seed origin had a marked effect on density and fluid uptake but the two factors showed no correlation. Some seed origins showed a variety of desirable characteristics and recommendations are made for the selection of seed origins for further UK plantations based on growth rate, density, tree form and permeability.
I Usta, M D C Hale
Natural durability, density and extractive contents of 42 wood species of Bangladesh.
2003 - IRG/WP 03-10490
Natural durability, density and major extractive contents of 42 lesser used or unused wood species of Bangladesh have been studied. Correlation analysis between these properties has been performed. It has been shown that natural durability of these species neither explained by water soluble nor by alcohol benzene extractive contents. Density has a weak but significant positive correlation with durability which indicates that density might have some influence on durability of these wood species.
S Akhter, K Akhter, S C Das
Eucalyptus globulus. Impregnability in relation with plantation and crop
1992 - IRG/WP 92-2402
Eucalyptus globulus Lasill is currently classified in Pr EN 350 on the basis of the characteristics of the first log. In practice, there are usually several following crops of branches developped on each stump in plantations. Up to a diameter of 8 cm, round wood of 2nd crop and further crops present a maximum of sapwood and characteristics which differ significantly from the basic classification and justify an amendment of the standard for the purpose of use in ground contact as impregnated stakes.
Dip-diffusion of dressed timber - Effect of drying
1990 - IRG/WP 3603
The effect of drying on BFCA dip-diffused, dressed, freshly sawn timber was determined by the depth of penetration of boron achieved on two test timber species, White Cheesewood (Alstonia scholaris) and Light Hopea (Hopea papuana). The results obtained showed that the light density White cheesewood was completely penetrated even after 3 days drying while Light Hopea, treated immediately achieved 5.2 mm penetration after 2 days diffusion and subsequently better after 14 and 21 days diffusion. Adequate penetration was only achieved after 14 and 21 days diffusion when there was delay between 30 minutes and 72 hours.
H C Konabe
A novel guide for the determination of the physical properties of wood including kiln drying and full-cell preservative treatment
2004 - IRG/WP 04-20298
An ideal flow chart for the sequential experimental determination of a range of physical properties relevant to wood drying and subsequent preservation was designed as a novel guide to assist wood scientists. In this manner, data assembly and experimental processing are shown. This was designed according to experience and published literature. Aspects emphasised in this review were the physical properties which effect the manner of processing particularly in respect to preservative treatment of wood. For this purpose a total of 93 references covering 8 topics (descriptive wood anatomy, physical properties of wood, shrinkage and swelling, wood density, moisture content, fibre saturation point, wood drying (by oven and kiln) and liquid permeability) were reviewed.
I Usta, M D C Hale
Variation in natural durability of British grown Douglas fir ((Pseudotsuga menziesii (Mirb.) Franco). Part I. Effect of density and growth rate
2002 - IRG/WP 02-10445
Seed origin trials of Douglas fir (Pseudotsuga menziesii) in Britain have provided important information on growth differences between origins (Lines, 1987), but the variation in wood properties between origins has not been reported. The present paper describes a study of the variation in natural durability against two brown rot fungi (Coniophora puteana and Postia (Poria) placenta) and in a fungal cellar test between four seed origins of Douglas fir. In addition to natural durability, tree diameter, heart-, sap- and total cross-sectional areas, density, bending properties, extractive content and composition were determined to examine their effect on natural durability. The effects of extractive content and composition on durability are discussed in a second paper (Part II: Effect of extractive content and composition). The proportion of the total variation in natural durability explained by differences between seed origins and differences between trees within origins were estimated to indicate the potential of tree breeding programmes for modifying this wood property. (Poria) placenta) and in a fungal cellar test between four seed origins of Douglas fir. In addition to natural durability, tree diameter, heart-, sap- and total cross-sectional areas, density, bending properties, extractive content and composition were determined to examine their effect on natural durability. The effects of extractive content and composition on durability are discussed in a second paper (Part II: Effect of extractive content and composition).
S Akhter, M D C Hale