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Promoting Commercially Available Epoxy Resins for Non-biocidal Wood Preservation
2019 - IRG/WP 19-40877
Commercially available epoxy and polyamine resins were evaluated with the aim of developing new non-biocidal wood preservation treatments. A simple method allowing the impregnation of wood by vacuum double impregnation followed by a curing process was developed for two reference species, beech Fagus sylvatica and Scots pine Pinus sylvestris. The tested products were evaluated for their ability to improve wood’s physico-mechanical properties, such as the anti-swelling efficiency (ASE) and resistance against biological agents (fungal decay, termites, marine borers). The weight percent gain (WPG) measured throughout the experimental steps was used to optimise the treatment parameters (such as dilution of the resins, curing temperatures, impregnation sequence). The best performing treatments demonstrated highly improved resistance against fungal decay, termites and marine borers, unusual patterns of attempted termite attacks being observed. Observations conduced on the termites’ and marine borers’ behavior suggest that the treatment applied to wood induces a starving effect and thus provides an indirect protection to the treated wooden samples. SEM analyses of the treated wood samples were also performed in order to determine if the polymers impregnated into wood tend to cure inside of the wood cell walls. These analyses demonstrated that wood polymers could be cured inside impregnated resin and then protected against water-related and biological damage. The last tests performed demonstrated that improving the penetration into wood cell walls of less concentrated products/polymers and optimizing the post-curing step are major issues for improving the resistance against fungal decay.
P Poveda, M Mubarok, S Dumarcay, M Montibus, I Le Bayon, M Kutnik, P Gerardin, F Simon


Principles and procedure of the planeing test
1981 - IRG/WP 2162
Small end-sealed samples of pine-sapwood (1.5 x 2.5 x 5 cm³) are treated by brushing and afterwards different parts of the treated surface are removed. The remaining part of the sample is tested against either insects or fungi. If no attack occurs sufficient amounts of biocides have been penetrated at least beyond the zone which has been removed. In spite of some problems the test seems the only suitable method, to evaluate organic solvent preservatives, mainly those containing resins, for simple treating methods.
H Willeitner, M Gersonde


Time dependent over-uptake of etherificated melamine resins
1998 - IRG/WP 98-40109
Waterbased methanol-etherificated melamine-formaldehyde resins can increase the fungal resistance of the treated wood though they are known to be non-toxic. Therefore melamine-resins are at the present an object of research activities of European projects and of some companies. The paper highlights the importance of quoting the duration of the diffusion when immersed in the treating solution, as major differences in the effectiveness against fungal attack can be obtained by extending the diffusion period. This paper also critically reviews the practice of referring the concentration of the solutions used for impregnation to a fixed solids content of this type of resins.
D Lukowsky, R-D Peek


Termiticidal chemicals derived from tropical tree resins
1991 - IRG/WP 1477
To test the hypothesis that defensive chemicals protect tropical primary forest trees against biological attack, a bioassay and fractionation program was conducted in Indonesia. Fresh dipterocarp resins were fed in no-choice tests to Neotermes dalbergiae termites on 4.5 cm filter papers, or tested for inhibition of fungal growth. Fractionation of biologically active resins via flash column chromatography, followed by subsequent bioassay and analytical chemical studies, revealed that several sesquiterpene compounds inhibited fungal growth and killed 50% of test termites in 3-7 days. Toxic fractions contained caryophyllene, caryophyllene oxide, alloaromadendrene, and other compounds. From the relatively non-toxic a-gurjunene, novel termiticidal compounds were synthesized, indicating the potential for manufacture of insecticides from natural products.
A Messer, K McCormick, D Richardson, Sunjaya, H Hagedorn, J Meinwald


Testing method for the treatability of wood
1994 - IRG/WP 94-40031
In order to test and classify the treatability of wood species in pressure treatment processes with water-based solutions, a laboratory method was developed which allows the testing of small samples and limited sections of a stem, e.g. sapwood. The penetration of different liquids was determined separately concerning the three anatomical directions of wood. The common parameters for pressure impregnation were used on sap- and heartwood of eight indigenous and tropical wood species. An elastic epoxy resin proved feasible for coating the samples on five sides. From the data of the testing method a measure for the treatability was calculated, allowing to classify wood species into four treatability classes analogous to prEN 350-2 (1993).
A O Rapp, R-D Peek


End grain sealants for wood preservation studies
1985 - IRG/WP 3341
The results of tests with possible end grain sealants for wood preservation studies are reported. The epoxy resins used gave satisfactory performance on wet or dry Sitka spruce and have been used with success for diffusion treatment studies.
R J Murphy, N A Summers


Improvement of some technological and biological properties of poplar wood by impregnation with aqueous macromolecular compounds
1992 - IRG/WP 92-3721
Poplars (Populus spp) belong to the most important tree species in afforestation programs of the Netherlands. Due to their rapid growth, the wood quality is usually low. Therefore, studies were performed to elucidate whether some technological properties and the resistance against fungal attack could be improved by impregnation with water-soluble resins. The results showed that swelling and shrinkage of poplar wood may considerably be reduced by a treatment with certain resins. The anti-shrink efficiency (ASE) strongly depends upon the resin type. An air-curing alkydresin based on polybutadiene and an air-curing acrylate modified alkydresin emulsion caused the best effects. Additions of wood preservatives to the resins further improved the ASE. Some disadvatages of the tested resins may be seen in their leachability with consequent loss of the dimension-stabilizing effects. The resins by themselves don't reveal fungistatic properties but an impregnation of poplar wood with these materials led in all cases to a better durability against Coniophora puteana and Coriolus versicolor. Leaching procedures influenced the durability in various ways. With resin/fungicide combinations, a good resistance against Coriolus versicolor could be reached even after leaching. SEM and EDXA methods were used to localize the resins in the cell walls and lumina and to detect the growth of mycelium in the specimens.
R D Peek, H Militz, J J Kettenis


Remedial treatments of glulam = diffusion of active ingredients through glue lines from solid wood diffusable preservatives
1996 - IRG/WP 96-30117
Diffusable preservatives are very suitable for use in remedial treatments of laminated beams in which too high moisture content involves the development of wood destroying fungi. The diffusion of active ingredients (boric acid, disodium octoborate, bifluoride) is well observed in solid wood but in a composite wood, the glue lines may appear not only as a barrier for the diffusion but also, may be mechanically affected by the diffused active ingredients. Shear tests were carried out on glulam specimens manufactured with different types of glues: resorcine (RF), ureaformaldehyde (UF), polyurethane (PUR) and polyvinylacetate (PVAc). Diffusion tests were also carried out in accelerated wetted glulam specimens with three diffusable solid preservatives differently exposed in the test samples. Results observed with boron compounds showed that their diffusion does not affect the mechanical resistance of the beams. In another hand, interesting results were obtained concerning the passage of boron and bifluoride through some types of glues. These results will contribute to the optimization of the remedial treatment of glulams.
D Dirol, S Mouras


Borate diffusion in wood from rods and liquid product. Application to laminated beams
1988 - IRG/WP 3482
In the aim to use borate preservatives (fused rods and boracol) in fields of building construction other than external joineries, tests of diffusion of borate rods and secondary boracol, were carried out on different species of woods exposed to different moisture conditions. Tests were also applied on laminated beams very often subjected to high moisture contents and thus decay of rot fungi. Diffusion was tested in different conditions and in relation, the action of these products was tried with stains and resins for improving strength properties. Diffusion tests on several species of wood confirm the proportionality already observed between moisture content and diffusion of borates in wood for all species. In a short time, test of diffusion on laminated wood showed a good diffusion in two lamella along the glue line leading to another way of boring. There is no problems between these borate products and stains or resins.
D Dirol


Biological resistance of wood treated with waterbased resins and drying oils in a mini-block test
1998 - IRG/WP 98-40107
In recent years it was found that the resistance of wood against fungal degradation could be increased by impregnation with an etherificated melamine formaldehyde resin. Using this resin as a reference, a waterbased fatty acid modificated alkyd-resin and two drying-oils were assessed for their biological performance in a mini-block laboratory test. Although drying-oils, like linseed-oil, are often used as a binder in paints, little information is available about the resistance of wood impregnated with these oils against wood destroying basidiomycetes. The fungi used in this test were the brown rot fungi Coniophora puteana, Gloeophyllum trabeum and the white rot fungus Trametes versicolor. The results showed considerable less mass loss of the melamine resin and the drying oils treated wood compared to the untreated Scots pine (Pinus sylvestris) controls. The mass loss of the oil treated specimens, however, was obviously depending on the fungus and the applied treatment and the wood species.
M Sailer, A O Rapp, R-D Peek


Addendum to paper for discussion in Working II
1970 - IRG/WP II 5B
In view of the limited time that will be available for discussions in Nancy, this addendum has been prepared. Arising from the previous collaborative work and Mr Bravery’s visit to most of the co-operating Institutes, a scheme of work entailing tests carried out 1) by a technique chosen by individual Institutes; 2) by an agreed standardised technique would appear to be the best approach. A complete programme of work would embrace a) agar tests; b) soil tests -in sterile soil -in unsterile soil. Clearly allocation of priorities eg to concentrate in the first place on tests in unsterile soil, will be needed. To facilitate discussion on a standardised technique, possible methods for conduct of both agar and soil tests are included in appendix I and II respectively. Full details of practical procedures and methods of computing results have not been included.
J G Savory, A F Bravery


Influence of different resin treatments on the dimension stability of wood
1997 - IRG/WP 97-40090
The dimension stability of wood is considered to be an important contribution to its durability and its performance in practice. A number of different treatments have been developed to improve the dimension stability of wood. One applied method is the treatment of wood with monomers or resins. The application of appropriate impregnation conditions seemed to be essential to enhance the efficiency of the treatment with water based resins. Therefore, wood samples of the three wood species Pinus sylvestris L., Pinus radiata D. Don. and Fagus sylvatica L. were impregnated with four different resin systems to evaluate the influence of different parameters on the anti-swelling efficiency (ASE). Variation in diffusion time, initial moisture content and resin concentration revealed considerable differences in retention of the resins and the ASE.
M Sailer, A O Rapp


Improvement of intrinsic properties of wood by chemical wood densification - Hydrophobic aspects and durability aspects
1999 - IRG/WP 99-40149
To improve the intrinsic properties of Scot pine wood ((1) hydrophobic surface and (2) durability), two ways of chemical modification have been tested. The first one is the chemical modification of hydroxyl groups by active substances like diisocyanate compounds with a copolymerization step. The second way is a densification by an impregnation of resins and a gamma polymerisation. This second way is described and discussed in this paper The measured parameters are (1) the hydrophobic properties of the surface based on permeability measurements and (2) the biological durability against wood decaying fungi and (3) the weathering behaviour. Significant results are presented and discussed to promote another way of wood preservation based on densification by resins.
G Labat, Q K Tran, I Le Bayon


Effect of some resin treatments on fungal degradation reactions
1999 - IRG/WP 99-10318
The effect of impregnation of wood with vegetable oil, tall oil and two water soluble on fungal degradation reactions was assessed by hydrolysis and enzyme activity measurements. The experiments were carried out by using isolated enzyme preparations and a living brown-rot fungus Poria placenta. The results indicate that the inhibitory effect of treatments was clearly directec towards the enzymatic hydrolyzability of the hemicellulosic and cellulosic components of wood cell wall. The water soluble resins and tall oil treatments significantly decreased the ability of isolated enzyme preparation to hydrolyse treated wood substrate. The inhibitory effect of these treatments was focused on the degardation of arabinoxylan and cellulose components of the wood cell wall. The vegetable oil treatment did not significantly prevent the enzymatic hydrolysis of wood substrate. The resin and tall oil treatments seemed also to interfere the production and/or mode of action of hydrolytic degradation pathway of living brown-rot fungus P. placenta.
A-C Ritschkoff, M Rättö, A J Nurmi, H Kokko, A O Rapp, H Militz


New principles for the protection of wood: Impregnation with waterborne resins
1995 - IRG/WP 95-40047
The environmental impact of classical wood preservatives as well as the use of tropical wood species with high natural durability is regarded increasingly critically in the public. Therefore other partially new principles for the protection of wood, like chemical modification, or treatment with resins were examined especially in USA, Japan and in Europe with promising results predominantly in the lab scale. The work to be presented is focused on the feasibility to upgrade wood by a wide spectrum of water-borne resins under practical conditions of processing. The chemicals examined range from purely physically effective resins by hydrophobation and mechanical blockage up to such promising a chemical modification by their reactive groups. The behaviour of the resin solutions in a pressure process as well as the penetration parallel and orthogonal to the grain were investigated. Further, resin-uptake, improvement of hardness, and dimension stability, were examined. SEM studies are intended to show penetration pathways and linkage of the resins to the cell wall. Running tests on the investigation of the resistance against basidiomycetes and softrot fungi are not yet completed.
A O Rapp, R-D Peek


Bending properties of wood after its decay with Coniophora puteana and subsequent modification with selected chemicals
1999 - IRG/WP 99-40146
Mechanical properties of wood are often decreased due to decay processes caused by biotic and/or abiotic factors. Damaged wooden elements (e.g. historical structures) can be reinforced by more methods, including their modification with convenient chemicals. This paper presents influences of selected chemicals on basic bending properties (modulus of elasticity - MOE, modulus of rupture - MOR) of sound and decayed wood. Norway spruce (Picea abies L. Karst.) and European beech (Fagus sylvatica L.) samples 8.5 x 8.5 x 120 mm (RxTxL) were deteriorated with the brown-rot fungus Coniophora puteana in laboratory conditions in the interval from 2 to 10 weeks. These rot samples as well as the sound ones were subsequently modified with 5 different chemicals (shellac, epoxy resin, melamineformaldehyde resin, polybutylmethacrylate, or polyethyleneglycol) using pressure impregnation technique (p = 0.8 MPa, t = 6 h). The MOE were evaluated continually for each sample in its sound, rot and modified state (or in sound and modified state), while the MOR just for groups of sound and modified samples. An apparently positive effect on the MOE was achieved with the melamineformaldehyde and epoxy resins, while the polybutylmethacrylate and shellac had only a gentle positive effect. The MOR was increased mainly with the epoxy resin. On the other hand, the polyethyleneglycol - PEG 1000 had an apparently negative effect on both bending properties.
L Reinprecht, S Varinska


In situ testing the influence of melamine resins on the enzymatic activity of basidiomycetes
1999 - IRG/WP 99-30194
Waterbased methanol etherificated melamine formaldehyde resins have the potential to increase the resistance of impregnated wood against wood destroying fungi. The mechanism of the increased wood durability is not clear yet. In the present paper the possible interference of melamine resins with wood degrading enzymes of Coniophora puteana and Trametes versicolor was investigated as a possible contribution to the increased wood durability. An in situ photometric assay was used to measure the enzymatic activity against Walseth cellulose, pine sapwood as well as lignin and xylan preparations.
D Lukowsky, F Büschelberger, O Schmidt


Preservatives stains as exterior wood finishes
1977 - IRG/WP 389
For many years wood preservatives and paints have been used as the only treatment for exposed wood surfaces. Because of the inherent color of the preservatives, such as creosote, the wood surface was stained as well as protected from attack by micro-organisms. Paints protect surfaces from weathering, but recently, with an increased interest in maintaining the more natural appearance of exterior wood surfaces, painting is being replaced by staining. Stains have the advantages, in addition to preserving the natural wood appearance, that they do not peel, blister or crack, can be applied easily and renewed with little difficulty. The cost is less than that of paint, initially and over the life of the building. One of the major attractions for homes is that stains blend in with the environment. If the home owner desires a white exterior or bright colors, paint rather than a preservative stain must be used. Paints are more effective in protecting the wood from damage by sunlight and will avoid discoloration of the exterior surface resulting from the natural extractives present in wood. Special aluminium or stainless steel nails are not needed with paints, but are needed with stains. Preservative stains can be classified in various ways. Wood preservatives, such as creosote and pentachlorophenol, have been used for many years primarily for preventing deterioration caused by fungi, including fungus species which discolor and those that decay the wood. These compounds provided some degree of water repellency, but this was not a major objective in their use. Later, water repellents were added to the preservatives to reduce the rapid uptake of moisture and thus provide some dimensional stability to the product. More recently water solutions of inorganic salts have demonstrated that they provide protection to the wood, add color and are beneficial primary treatments if the wood surface is to be painted. Some of the water soluble formulations may provide some fire retardant properties as well. A common system of classification today includes three general types of natural finishes as follows: 1. water-repellent preservatives; 2. pigmented penetrating stains; 3. inorganic water soluble salts. It is possible to obtain a satisfactory exterior surface if no treatment is applied. Such an approach, however, is satisfactory only where the weather is not favorable for micro-organisms. If the fungi and other micro-organisms are allowed to develop, the coloring will be very nonuniform, the wood surface will deteriorate, and warping and the like will occur to excessive degrees. Thus in most environments one of the above systems must be used.
D W French


Compatibility of deltamethrin with wood adhesives
1993 - IRG/WP 93-30031
This work presents the studies conducted on the compatibility of deltamethrin when mixed with wood adhesive to manufacture plywood in order to protect the wood against wood-borers insects and termites. The following types of adhesive were tested: PVA, Urea-formaldehyde, phenol-formaldehyde and a formulation based on tannin. The experiments were made in the adhesive manufacturers' laboratories, where the conditions to which the adhesives are submitted during the manufacturing process were simulated. To verify the effectiveness of the adhesive mixed with deltamethrin the block tests were exposed to subterranean termites, Coptotermes havilandi. The tests showed that the internal layers of the plywood made with adhesives based on PVA and Urea-formaldehyde were protected for 40 months.
A M F Oliveira


Melamine resins as preservatives results of biological testing
1996 - IRG/WP 96-40061
Based on previous work of the authors on resins, the upgrading of wood with a true solution of a methanol etherificated melamine resin in low aqueous concentration was performed. For the relative assessment of the biological resistance against brown and white-rot fungi were used not only untreated controls of pine sapwood (Pinus sylvestris L.), but also heartwood of European larch (Larix decidua Mill.). Even at the lowest applied concentration of 7.5% resin in the treating fluid (about 10% weight gain), the treated wood showed considerably less mass loss than heartwood of European larch. Leaching according to EN 84 resulted in no difference. The above outlined is valid for lab tests according to EN 113. First results of ongoing experiments with samples in soil contact exhibited general problems of testing modified and resin treated wood, using standard methods made for classical wood preservatives.
A O Rapp, R-D Peek


Photostabilization of Wood with Higher Molecular Weight UV Absorbers
2010 - IRG/WP 10-30524
Higher molecular weight UV absorbers were created by reacting the epoxy-functionalized UV absorber 2-hydroxy-4(2,3-epoxypropoxy)-benzophenone (HEPBP) with maleic, phthalic or succinic anhydride. The ability of the UV absorbers to photostabilize wood was then examined. FTIR-spectroscopy confirmed that HEPBP reacted with phthalic anhydride to create a polyester that preserved the UV-absorbing benzophenone group. There was less evidence that the polyester was formed when HEPBP was reacted with maleic or succinic anhydride. HEPBP-phthalic anhydride was the most effective UV absorber at photostabilising wood. This UV absorber showed increased UV absorption around 270 nm, formed a leach-resistant film at wood surfaces and was able to restrict both weight and tensile strength losses of thin wood veneers during accelerated weathering, unlike chromium trioxide and a UV absorber-hindered amine light stabilizer. We conclude that higher molecular weight polyester-type UV absorbers show promise as a way of photostabilizing wood and briefly discuss how more effective systems could be developed.
P D Evans, M J Chowdhury


Bio-based thermoset resins for bonding and eco-friendly preservation in the wood industry
2013 - IRG/WP 13-40650
Yellow dextrins and tannins were used in wood adhesives formulation to substitute resins based on formaldehyde. Several formulations were carried out in alkaline aqueous media by varying the weight fraction of two compounds from 10% to 30%. The cross-linking was performed using epichlorohydrin as a reticulant agent. Rheological behaviours and initial adhesion of three liquid formulations, before reticulation, were carried out by probe tack test and Rheology to validate its process ability. The cross-linking of epichlorohydrin with yellow dextrins and tannins was highlighted in this study. The cross-linking was analyzed by Fourier transformed infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and by biodegradation of reticulated resins. Mechanical properties of resins were analyzed by shear strength test on plywood. Depending on formulations, results confirmed the high potential of yellow dextrins and tannins reticulated by epichlorhydrin, to glue wood. Moreover, the biodegradation tests of cross-linked samples showed that the network constituted by dextrins and tannins are resistant to fungal attack.
C Motillon, A Allal, A Visse, F Charrier, B Charrier, A Baldé


Decay resistance of beech wood and plywood treated with different type of phenol-formaldehyde (PF) resins
2016 - IRG/WP 16-40717
In this study treatment of beech and poplar wood veneers with (PF) resin industrial scale and screening tests of nine different phenol-formaldehyde (PF) resins were made. Specifically, the effect of different phenol-formaldehyde (PF) resin types on the resistance of beech wood against brown- and white-rot fungi was evaluated. Criteria for selection of optimal (PF) resin were based on minimum WPG requirements to achieve equal durability class (1st durability class according to the EN 350 standard) against fungi. Therefore European beech (Fagus sylvatica) wood blocks (15x20x50 mm³) were vacuum impregnated to various weight percent gains (WPGs) with water-soluble PF resins. Different WPG levels were achieved by using aqueous resin solutions at concentrations of 9, 18 and 27 wt %. Treated wood blocks were exposed to brown-rot fungi (Gloeophyllum trabeum (G.t); Coniophora puteana (C.p)) and white-rot fungi (Trametes versicolor (T.v); Pleurotus ostreatus (P.o)) for 16 weeks. A WPG of approximately 8–14% was necessary for beech wood blocks for a treated with the resin C, D, I and E, but approximately 16% and 27% was necessary when using other resins as B, F, G, H, respectively. Irrespective from resin the required WPG for decay resistance against brown rot fungi was approximately 50-60% lower compared to decay resistance against white rot. No effect of resin on the resistance against (G.t) decay of wood blocks was observed, resulting in resin loadings of 7–8%, whereas the required WPG for (C.p) decay suppression slightly increased from 8 up to 11%, respectively. The results suggest that the magnitude of white fungal deterioration of treated wood is strongly affected by the resin used for treatment. Resin loadings from 7% to 17% against (T.v) and from 12% to 27% against (P.o) were required. This broad range in WPG may be due to varied fungal aggressiveness, filling of the cell wall micropores (bulking) and the stiffness (pliability) of the cell wall matrix. From aforementioned, two resins D and E were selected for treatment of beech and poplar veneers on industrial scale and resistance of treated plywood against white rot fungus (T.v) was evaluated according EN 12038 standard.
V Biziks, S Bicke, H Militz


Improvement of wood properties by impregnation with liquefied spruce bark based resins
2016 - IRG/WP 16-40761
In this paper, biobased phenolic thermosetting resins are designed to be used as wood stabilization treatment. The originality of the study stands in substituting part of phenol by spruce (picea abies) bark: this is achieved by a liquefaction process in phenol in the presence of sulfuric acid as catalyst. Next, thermosetting resins are synthetized from liquefied bark by condensation on formaldehyde and further used for impregnation in beech blocks and curing. Two kinds of spruce barks -unmodified and pretreated ones- are used as starting material and characterized. Concerning pretreatment, a hydrolysis has been applied to spruce bark in order to enhance phenolic part. Two liquefaction processes are compared: the first one a simple heating under reflux in presence of phenol. A second one consists in heating at 200°C in closed reactor in phenol/ethanol/water solvent (20/50/30). For the different systems attempted, liquefaction yields are determined and analyzed regarding FT-IR analysis. 91% yield was obtained for liquefied spruce bark under reflux, but the highest bark to solvent ratio (50%) was obtained for process lead in closed reactor. Reactivity of liquefied bark resins is found to be better than control phenolic-formaldehyde resin. Impregnations in beech (Fagus sylvatica) wood blocks are performed using different dried matter content (10%, 20% and 30%). After curing, weight percent gain (WPG), leaching rate, anti-swelling efficiency (ASE) and resistance to decay of different systems are compared. It is shown that liquefied bark based resins confers to wood significant dimensional stabilization and resistance to decay against brown rot and white rot fungi. Concerning the impact of the different processes attempted such as hydrolysis pretreatment or liquefaction at 200°C in closed reactor, final properties of treated wood are decreased compared to liquefied bark resins.
X Duret, E Fredon, E Masson, P Gérardin


Chemical compositions and anti-termite activities of essential oils from Gabonese Canarium schweinfurthii Engl, Dacryodes buettneri Engl and Aucoumea klaineana Pierre wood resins.
2017 - IRG/WP 17-10895
Essential oil extract from resins of Canarium schweinfurthii, Dacryodes buettneri and Aucoumea klaineana woods from Cap Esterias and Oyem areas, Gabon, were prepared by Clevenger - steam distillation. The chemical compositions of these respective essential oils were analyzed by a Gas Chromatography coupled with Mass Spectrometry (GC-MS). Although monoterpenes were the main constituents of the three essential oils, each wood resins had a various essential oil yield after steam distillation process [6,92% (A. klaineana), 4,20% (C. schweinfurthii) and 13,19% (D. buettneri)] and their respective chemical compositions were slightly different. It results that monoterpenes, as α –pinene, o-cymene, alpha-phellandrene and D-limonene form the major constituents of terpenoides and phenylpropanoïdes compounds which are the most active substances against termite activity. The anti-termite activities of the three essential oils were evaluated, performing no-choice tests. 70 μL of each essential oil diluted in acetone with mass ratios of 50:50 and 25:75 [essential oil: acetone] were impregnated on Whatman papers and exposed to termite (Reticulitermes flavipes). Essential oil from Canarium schweinfurthii resin showed the strongest inhibitory activity against the termite with 100% mortality after 1 day at 50:50 and 25:75 concentrations followed by Aucoumea klaineana resin with the 100% mortality after 3 days at 50:50 and 25:75 concentrations. Finally, essential oil from Dacryodes buettneri resin showed the lowest termite resistance with 48.34 % and 58.34% mortalities after 14 days at 50:50 and 25:75 concentrations, respectively. The number of chemical components from each essential oil and their respective quantity, determined by GC-MS, are related to their anti-termite activity level.
Chemical compositions and anti-termite activities of essential oils from Gabonese Canarium schweinfurthii Engl, Dacryodes buettneri Engl and Aucoumea klaineana Pierre wood resins.


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