Effect of essential oil compounds and plant extracts on decay and termite resistance of wood

Essential oils and their derivatives have a long history of safe usage as antimicrobial agents in food industry. In this study various essential oils and extracts from plants were screened for their ability to inhibit wood decay and termite attack in laboratory decay and termite resistance tests using treated wood specimens. In the laboratory decay resistance tests, wood specimens treated with essential oil compounds were subjected to brown-rot fungus, Tyromyces palustris, and white-rot fungus, Trametes versicolor for three months. The specimens were also subjected to termite attack by subterranean termites, Coptotermes formosanus for three weeks in laboratory conditions. The formulation with cinnamaldehyde (DF3) was found to be effective against both the brown-rot and white-rot fungi used in the study. However, the formulation with cinnamic acid (DF8) was able to protect wood specimens against only the white rot fungus and about 50% mass loss occurred in the specimens subjected to the brown-rot fungus. The mass losses in the wood specimens treated with cassia oil containing formulation (DF4) showed that cassia oil was effective against both fungi. The wood tar oil and dodecanal compounds also inhibited fungal decay in the specimens. The wood specimens treated with the formulations used in termite resistance tests were more resistant against the termites when compared to specimens treated with the formulations in decay resistance tests. Even after severe weathering process, treated wood specimens showed resistance against the subterranean termites. Results suggest that essential oils and plant extracts might be important to develop new wood preservatives that are less harmful to the environment and humans than recently available ones.     

Laboratory evaluation of boron-containing quaternary ammonia compound, didecyl dimethyl ammonium tetrafluoroborate (DBF) for control of decay and termite attack and fungal staining of wood

This study evaluates the decay and termite resistance of wood treated with didecyl dimethyl ammonium tetrafluoroborate (DBF), a recently developed quaternary ammonia compound containing boron. Laboratory decay resistance tests were performed using brown-rot fungus, Fomitopsis palustris and white-rot fungus, Trametes versicolor. Treated wood specimens were also subjected a 3-week-termite resistance test using subterranean termites, Coptotermes formosanus. Decay resistance tests showed that wood specimens treated with 0.5 and 1.0% DBF solutions were well protected against both fungi even after a 10-day severe leaching process, suggesting the adequate fixation of DBF in wood. DBF treatment at 0.1% concentration was efficient against subterranean termites, Coptotermes formosanus Shiraki based on mass losses in both leached and unleached wood specimens. The ability of DBF to inhibit discolorations by selected mold and stain fungi was also screened in laboratory conditions. DBF at the highest concentration level (1%) provided limited protection against mold and staining fungi tested, however, it was effective for only short-term protection (1 or 2 weeks) at lower concentrations. These results suggest that DBF is promising to protect wood to be used outdoors against both fungal decay and termite attack however field tests are needed to observe the performance of DBF-treated wood in ground contact.     

Zum Stand der Imprägnierung und Prüfung geschützter Holzwerkstoffe (Typ V 100 G)

The effective application of preserving treatments for wood based materials calls for the development of suitable testing and evaluation procedures. According to their economic standing as building materials, protective treatments for plywood and particleboards take priority. Experiments were carried out with plywood, using a laboratory decay test with fungi in which determination of loss of mass was combined with compression strength testing. For the preservation of fibreboards dipping and pouring processes are the most promising methods of preservative application. Decay tests carried out with particleboard showed that for fungus cellar tests simultaneous wet chamber storage (without fungal attack) was necessary for comparison. Loss of mass and strength by leaching or by respective microbiotic invasion are diseussed.     

Fungal and termite resistance of wood treated with 4-methoxytrityl tetrafluoroborate

This study evaluates the decay and termite resistance of Scots pine (Pinus sylvestris L.) treated with 4-methoxytrityl tetrafluoroborate (MTFB). Decay resistance tests of unleached samples showed that 2%, 1.5% and 1% concentrations of MTFB (15.4 kg/m³, 11.1 kg/m³, and 7.4 kg/m³, retention levels, respectively) gave less than 2% decay of Postia placenta and concentrations of 2% and 1.5% less than 2% decay of Coniophora puteana. Wood specimens treated with 4-methoxytrityl tetrafluoroborate solutions were not protected against the brown rot fungi after a 14-day severe leaching process, suggesting excessive leaching of the chemical from wood. Treatment with 2% concentration protected against subterranean termites, Coptotermes formosanus Shiraki based on mass losses in both leached and unleached wood specimens in comparison with lower concentration levels. These results suggest that 4-methoxytrityl tetrafluoroborate might be promising to protect wood being used outdoors against termite attack. However, 4-methoxytrityl tetrafluoroborate did not protect wood against fungal decay. Field tests are needed to observe the performance of 4-methoxytrityl tetrafluoroborate treated wood in ground contact.     

Surface treatment for preventing decay and termite attack in wood using didecyl dimethyl ammonium tetrafluoroborate (DBF) incorporated with acryl-silicon type resin

Surface treatment of wood was carried out using acryl-silicon type resin including didecyl dimethyl ammonium tetrafluoroborate (DBF), boron-containing quaternary ammonia compound. Surface-treated wood specimens were exposed laboratory decay resistance tests after completing a 10-cyle severe weathering process. In laboratory decay resistance tests, one brown-rot decay fungus, Fomitopsis palustris and one white-rot decay fungus, Trametes versicolor were used. The specimens were also subjected to laboratory termite resistance tests using subterranean termites, Coptotermes formosanus. Wood specimens treated with 2% DBF and resin containing preservative solution showed improved decay and termite resistance suggesting that the preservative solution at 2% DBF concentration provides lasting protection against wood degradation owing to the amount of DBF remaining in the wood after severe weathering process. However field tests are needed to determine the performance of surface-treated wood with DBF and the acryl-silicon type resin in more realistic conditions.     

Fungal resistance and physical–mechanical properties of beech plywood having durable veneers or fungicides in surfaces

Improvement of insufficient fungal resistance of beech plywood for wet conditions was examined by: (1) incorporation of durable oak (Quercus robur) or black locust (Robinia pseudoacacia) surface veneers instead of beech (Fagus sylvatica) ones; (2) primordial treatment of beech surface veneers with 0.5, 1, 1.5 and 3 % solutions of fungicides DDAC, IPBC, Propiconazole and Tebuconazole; (3) additional treatment of beech plywood with the same fungicides. The anti-fungal efficiency of these three methods, applied to five-layer plywood boards glued with phenolic resin, was assessed either by decay test with two brown rot fungi (Coniophora puteana and Serpula lacrymans) and one white rot fungus (Trametes versicolor) using edge protected specimens according to modified ENV 12038, or by mould test with two microscopic fungi (Aspergillus niger and Penicillium brevi-compactum) according to modified EN 15457. The durability of beech plywood significantly increased after incorporation of black locust veneers into the surface layers, and also thanks to organic fungicides (0.5 % IPBC, Propiconazole or Tebuconazole, and 1.5 % DDAC) present in the surfaces. Other selected properties of beech plywood were sometimes influenced positively (e.g., soaking due to less permeable black locust and oak surface veneers) or negatively (e.g., shear strength due to fungicides).     

Effect of heat treatment intensity on wood chemical composition and decay durability of Pinus patula

Heat treatment is an effective method to improve biological resistance of low natural durability wood species. The aim of this study was to enhance the decay resistance of Pinus patula, an African low natural durability softwood species, via wood thermal modification technique. Heat treatment was performed on wood specimens under inert conditions at different heat treatment intensities to reach mass losses of 5, 10 and 15%. Heat treated specimens were exposed to fungal decay using the brown rot fungus Poria placenta. The wood chemical and elemental composition was determined as well as extractives toxicity before and after wood thermal modification to understand the reasons of durability improvement. The treated specimens exhibited a significant increase in their durability against wood decay in line with the severity of the treatment. Wood holocellulose was found to be distinctly more sensitive to the heating process than the lignin constituent. In addition, obvious correlations were observed between weight losses recorded after fungal exposure and both holocellulose decrease and lignin ratio increase. The same correlations were observed with the elemental composition changes allowing using the observed differences for predicting of wood durability conferred by heat treatment. Furthermore, no significant differences were observed between the toxicity of Pinus patula wood extractives before and after its thermal modification.     

Utilisation of chemically modified lampante oil for wood protection

Within the Slovenian region of Istria, the olive growing and oil production industry is strong. This industry has a long history and the olives grown here have high levels of biologically active compounds including a variety of phenolic compounds. Using residual materials generated by this industry in potential wood protection systems would not only valorise low-value materials and stimulate rural economies but would also provide an alternative to currently used oil-based protection systems. The objective of this study was to produce an oil treatment for wood protection and assess its efficacy in reducing leaching, weathering effects, and fungal decay. Two maleinisation techniques were used to chemically modify low-value lampante oil in an attempt to limit leaching when impregnated in wood. Pinus sylvestris (Scots pine) and Fagus sylvatica (European beech) were treated with the modified oils and underwent leaching, accelerated weathering, and decay tests. Leaching of the treatment oils was relatively low compared with other experiments and beech wood specimens treated with a direct maleinisation treatment showed improvement in performance compared to control specimens. In addition, it was found that the modified oils were not completely removed from the wood after solvent extraction indicating that they could potentially be used as an immobilisation agent in combination with other treatments thereby reducing the amount of active component of the protective agent.     

A comparative study on brown-rot fungus decay and subterranean termite resistance of thermally-modified and ACQ-C-treated wood

The resistance of thermally-modified and Alkaline Copper Quaternary type C (ACQ-C) treated aspen (Populus tremuloides Michx), jack pine (Pinus banksiana Lamb.), yellow-poplar (Liriodendron tulipifera L.), and Scots pine (Pinus sylvestris L.) against the brown-rot fungus (Gloeophyllum trabeum) and Eastern U.S. subterranean termite (Reticulitermes flavipes) was studied. Wood materials were thermally-modified at a temperature of 210 °C for 15 min. ACQ-C was impregnated into yellow-poplar and jack pine wood at three different retention levels and at each level both leaching and non-leaching procedures were conducted. Results indicate that ACQ-C-treated yellow-poplar and jack pine became significantly more resistant to the brown-rot fungus compared to the thermally-modified wood and the untreated control. Thermally-modified yellow-poplar and jack pine were more resistant to this fungus than untreated wood. For aspen and Scots pine, the resistance to G. trabeum was improved after the thermal modification, but it remained susceptible to this brown-rot fungus decay. Termite susceptibility of thermally-modified aspen, jack pine, and yellow-poplar was comparable to that of untreated controls. Significantly greater termite attack occurred on thermally-modified Scots pine wood than it did on untreated wood. This likely is attributed to some compounds contained in Scots pine wood that inhibited termite attack.     

Potential of near infrared spectroscopy to assess hot-water-soluble extractive content and decay resistance of a tropical hardwood

The ability to identify both low- and high-durability samples in a population of naturally durable samples would allow more rational use of these materials, for example, using samples in the lower ranges of durability in non-soil contact. One possible method for rapidly assessing differences in heartwood characteristics related to durability is near infrared spectroscopy (NIR) coupled with multivariate statistical methods. A number of recent studies suggest that NIR can be related to a variety of wood properties, including extractive content. There are, however, few data on the ability of this technique to assess decay resistance, especially in hardwoods or species with high natural durability. In this report, the ability of NIR to predict both extractive content and resistance to fungal attack in Goncalo alves (Astronium graveolens) was assessed. NIR spectra accurately predicted hot-water-soluble extractive content of A. graveolens and its susceptibility to the white rot fungus Trametes versicolor. A. graveolens was very resistant to attack by the brown rot fungus Gloeophyllum trabeum and NIR spectra were not useful predictors of weight loss. NIR spectroscopy may be a useful tool for rapidly assessing the extractive content and decay resistance of naturally durable wood.     

Boron addition to non- or low-formaldehyde cross-linking reagents to enhance biological resistance and dimensional stability of wood

and Coriolus versicolor, which are the representative test fungi of brown- and white-rot in Japanese Industrial Standard (JIS) A-9201-1991, respectively. PBA had somewhat less contribution to decay resistance of GX most possibly due to chemical complexation. GA proved superior in decay resistance to the other two reagents. Mass loss due to the Formosan termite Coptotermes formosanus attack could be reduced to a minimum with total inactivation of termites by PBA addition. BA retention did not suffice to impart complete termite resistance after ten cycles of severe weathering of the specimens. Thus, BA was found appropriate to be added to the used cross-linking agents in such service conditions where decay risk is high while PBA combinations should be preferred if termite damage prevailes.     

Enhanced fungal resistance of Scots pine (<Emphasis Type="Italic">Pinus sylvestris</Emphasis> L.) sapwood by treatment with methyltrimethoxysilane and benzalkoniumchloride

This paper presents possibilities for increasing the decay and mould resistance of Scots pine (Pinus sylvestris L.) sapwood by treatment: (1) in one step with mixtures of aqueous solutions of methyltrimethoxysilane (0, 5, 10, 20 or 30 % MTMS) and benzalkoniumchloride (0, 0.5, 1, 2 or 3 % BAC), and (2) in two steps, first with BAC and then with MTMS. Prior to fungal resistance tests, the treated and reference specimens were not or were subjected to artificial ageing in distilled water and in Xenotest, respectively. Insufficient anti-decay efficiency of MTMS against the brown-rot fungus Coniophora puteana and the white-rot fungus Trametes versicolor was improved in the presence of BAC, usually more apparent if this fungicide was used first and in higher concentrations. After both artificial ageing modes, the decay resistance of treated pine specimens decreased approximately 1.2–1.8 times. The none anti-mould efficiency of MTMS improved in the presence of BAC—significantly against the mould Penicillium brevicompactum but only minimally against the mould Aspergillus niger.     

Evaluation on some finishing properties of oil palm plywood

Oil palm is the largest and most important plantation crop in Malaysia. The oil palm generally lasts for 25–30 years before the next replantation is done. Substantial amount of biomass in the form of palm trunk results from plantation cycle. This resource is simply left on the ground to decay and is not used as raw material to manufacture any kind of value-added products. The objective of this study was to investigate the possibility of manufacturing plywood from oil palm trunks and to evaluate some of the finishing properties of such experimental panels in comparison to those from Shorea sp as control samples. Three-ply plywood samples were produced from 5 mm thick veneers of oil palm using urea formaldehyde adhesive. Three types of chemicals, namely nitrocellulose, pre-catalyzed lacquer and polyurethane were used to finish experimental panels. The surface finished with nitrocellulose had the lowest contact angle on raw surface of oil palm plywood and wood. The average cross cut tape index of oil palm plywood was comparable to Shorea sp. All finishing materials of oil palm plywood produced impact rating of 4 except for surface finished with nitrocellulose while finishing on wood indicated an impact rating of 3. Oil palm plywood had higher weight loss compared to Shorea sp. Based on results from contact angle, cross cut tape index, impact rate test, weathering, and soil burial test methods it appears that the samples showed acceptable finishing properties comparable to those of solid wood.     

Influence of fungal decay by different basidiomycetes on the structural integrity of Norway spruce wood

The potential influence of diverse decay patterns caused by different brown rot causing basidiomycetes on the structural integrity of wood was investigated. Therefore, decayed Norway spruce (Picea abies Karst.) specimens representing a wide range of mass loss, caused by four different brown-rot fungi and one white-rot fungus, were applied to a high-energy multiple impact (HEMI)-test series. The relationship between the resistance to impact milling (RIM) and the mass loss by fungal decay could be subdivided into three areas: 1. Prior to measurable mass loss, a strength reduction was detectable due to the depolymerisation of wood cell wall components. 2. Between 0 and 25–30% mass loss, RIM decreased with increasing mass loss. 3. Above 30% mass loss, RIM increased again due to gluing effects of the fungal mycelium. The influence of the different brown rot fungi on the structural integrity of the wood differed slightly, but partly significantly.     

Effects of water glass and DMDHEU treatment on the colonisation of wood by Aureobasidium pullulans

Specimens of Scots pine sapwood (Pinus sylvestris) and beech (Fagus sylvatica) were treated with a sodium water glass solution and 1,3-dimethylol-4,5-dihydroxyethylene urea (DMDHEU). The pH-values of water glass treated specimens were between 9.7 and 12.0. Those of DMDHEU treated specimens were 3.8 (Scots pine) and 4.2 (beech). The resistance observed in an eight weeks laboratory test against the blue stain fungus Aureobasidium pullulans showed that treatments with water glass and DMDHEU reduced but not prevented the fungal growth. Wood specimens treated with water glass showed the lowest colonisation of blue stain. Both treatments inhibited fungal penetration through the ray cells. HPLC analysis showed that the amount of simple sugars was reduced due to water glass treatment. The amount of simple sugars in DMDHEU treated wood depended on the wood species. The amount of available sugar monomers did not indicate an influence of the colonisation of the sample surface.     

Surface treatment for preventing decay and termite attack in wood using didecyl dimethyl ammonium tetrafluoroborate (DBF) incorporated with acryl-silicon type resin

Surface treatment of wood was carried out using acryl-silicon type resin including didecyl dimethyl ammonium tetrafluoroborate (DBF), boron-containing quaternary ammonia compound. Surface-treated wood specimens were exposed laboratory decay resistance tests after completing a 10-cyle severe weathering process. In laboratory decay resistance tests, one brown-rot decay fungus, Fomitopsis palustris and one white-rot decay fungus, Trametes versicolor were used. The specimens were also subjected to laboratory termite resistance tests using subterranean termites, Coptotermes formosanus. Wood specimens treated with 2% DBF and resin containing preservative solution showed improved decay and termite resistance suggesting that the preservative solution at 2% DBF concentration provides lasting protection against wood degradation owing to the amount of DBF remaining in the wood after severe weathering process. However field tests are needed to determine the performance of surface-treated wood with DBF and the acryl-silicon type resin in more realistic conditions.

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Oberflächenbehandlung durchgeführt mit Didecy – dimethyl – ammonium – tetrafluorborat (DBF) in Kombination mit Acryl - Silicon - Harz als Schutzmaßnahme gegen biologischen Abbau und Termitenbefall von Holz

Zusammenfassung Oberflächenbehandlung von Holz wurde mit einem Acryl-Silikon Harz einschließlich Didecyl – Dimethyl – Ammonium – Tetrafluorborat (DBF) vorgenommen, eine borhaltige quaternäre Ammonium - Komponente. Oberflächenbehandelte Holzproben wurden nach dem Durchlaufen 10 vollständiger strenger Witterungszyklen im Labor Fäulnisresistenztests unterzogen. Dabei wurden ein Braunfäulepilz Domitopsis palustris und ein Weißfäulepilz, Trametes versicolor benutzt. Mit denselben Proben wurden im Labor auch Termitenresistenzversuchen mit der unterirdischen Termitenart Coptotermes formosanus durchgeführt. Proben, die mit 2% DBF und einem konservierungsmittelhaltigem Harz behandelt waren, zeigten verbesserte Fäulnis- und Termitenresistenz, was nahe legte, dass die Konservierungslösung mit 2%iger DBF - Konzentration dauerhaften Schutz gegen Holzabbau liefert, auf Grund der Menge an DBF, die nach dem strengen Witterungsprozess im Holz verbleibt. Um die Dauerhaftigkeit der Resistenz von Holz, dessen Oberfläche mit DBF und Acryl-Silicon - Harz behandelt wurde, festzustellen, sind allerdings Freilandversuche unter wirklichkeitsnahen Bedingungen erforderlich.

     

Fire performance and decay resistance of solid wood and plywood treated with quaternary ammonia compounds and common fire retardants

In this study, the fire performance and decay resistance of solid wood and plywood treated with quaternary ammonia compounds (didecyl dimethyl ammonium chloride (DDAC) and didecyl dimethyl ammonium tetrafluoroborate (DBF)) were compared with the performance of untreated control specimens and specimens treated with common fire retardants ((monoammonium phosphate (MAP), diammonium phosphate (DAP) and ammonium sulphate (AS)). Test specimens were treated with 1% and 4% (% m/v) aqueous solutions of the chemicals. The fire performance tests were the fire tube test (ASTM E 69) which measures mass losses in the specimens and the cone calorimeter test (ASTM E 1354) which measures mass loss, heat release rate, time for sustained ignition, effective heat of combustion, and specific extinction area. The results from the cone calorimeter tests were used to estimate the flame spread index (FSI) in the Steiner tunnel test (ASTM E 84). Heat release rates of the specimens treated with MAP, DAP, and AS were lower than those of both DDAC and DBF-treated specimens and the untreated control specimens. Compared with the untreated specimens, higher heat release rates were observed for the specimens treated with the quaternary ammonia compounds, DDAC and DBF. The estimates for the FSI for DDAC and DBF were for values equal to or higher than for the untreated control specimens. At higher concentration levels, MAP, DAP and AS were effective in decreasing initial contribution of heat release to potential fire. Decay resistance tests were done according to AWPA E 10 standard method using one brown-rot fungus and one white rot-fungus. Decay resistance tests revealed that solid wood specimens treated with DDAC and DBF showed resistance against the fungi tested, however, MAP, DAP and AS did not provide complete protection. While DBF and DDAC increased resistance of plywood specimens, high mass losses in plywood specimens treated with MAP, DAP and AS were obtained.     

Untersuchungen zur Optimierung des Oberflächenschutzes von Holzbauteilen

T-shaped specimens, jointed by mortise and tenon, simulating a critical part of window frames, were exposed to open air weathering for three years. The parameters tested were various wood species and surface treatments, including pretreatments by dipping in water repellent preservatives. The evaluation criteria were the changes of moisture content in time, measured by weighing over a period of two years, and the state of conservation of the specimens after three years. The capillary absorption of rain water by the wood species subjected to the treatments proved to be a significant factor for the intensity of changes in moisture content, as well as for decay resistance. Scots pine and beech showed the largest variations, spruce medium, and sipo and meranti only little change in moisture content, few cracks and low deformation. Most beech and pine, and a few of the spruce specimens showed substantial decay, whereas sipo and meranti (dark red) resisted quite well. Fungicide and water repellent pretreatments as well as film forming surface coatings of relatively low permeability to water vapor offered the best protection against moisture damage.     

The protective effect of 23 paint systems on wood against attack by decay fungi

A laboratory method was used to evaluate the protective effect of 23 different paint systems on Norway spruce wood against decay fungi. Weather-o-meter treated and non-treated paint films on wood were tested. Results were compared to those obtained on unprotected spruce wood. Finishes included in the study were primer oils, solvent-borne alkyd paints, water-borne acrylic paints, water-borne mixed alkyd/acrylic paints, alkyd emulsions and stains in different paint system combinations with one to four coats. The growth of the decay fungi of the paint films was estimated by visual inspection. After 5 months of incubation, microbial activity in the wood below the paint films was evaluated. Growth of the fungi in the wood below the paint film was measured by an indirect chemical method for estimation of microbial activity. Paint systems including a solvent-borne alkyd coat usually had a good performance when tested without prior weathering but degenerated most during the weathering process as judged from the altered water absorption and fungal growth rate. Paint systems including a treatment with a primer oil exhibited low moisture uptake also after weathering. A clear effect of fungicide additions was also seen. A water-borne penetrating oil with an acrylic top coat exhibited no visual surface attack before weathering, and low microbial activity in wood for all decay fungi before and after weathering.     

Fungal decay of viscoelastic thermal compressed (VTC) wood

Low-density hybrid poplar (Populus deltoides × Populus trichocarpa) was densified with the viscoelastic thermal compression (VTC) process to three different degrees of densification (63%, 98%, and 132%). Durability of the VTC treated specimens was assessed by exposure to two white rot fungi (Pleurotus ostreatus and Trametes versicolor) for four or eight weeks. After incubation, mass loss in grams and percentage mass loss were determined. The results showed that VTC densification did not change decay resistance to Pleurotus ostreatus and Trametes versicolor. The mass losses caused by Trametes versicolor were more extensive than those by Pleurotus ostreatus. As expected, longer exposure time resulted in higher mass loss. Furthermore, the degree of densification did not influence susceptibility to fungal degradation.