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The efficacy of commercial silicones against blue stain and mould fungi in wood
2008 - IRG/WP 08-30471
Scots pine (Pinus sylvestris L.) wood samples were vacuum pressure impregnated with quatsilicone micro emulsion (<40 nm particle size), aminosilicone macro emulsion (110 nm) and silicone macro emulsion with alkyl modified side groups (740 nm) and the resulting material properties were studied. Quatsilicone micro emulsion resulted in maximum bulking (4.8%) and anti-swelling efficiency (21.8%) in wood when treated with 30% concentration of silicone in treatment solution. All three chemicals made wood hydrophobic which was evident from capillary (longitudinal, tangential and radial) water uptake test adapted according to DIN 52617. Blue stain test EN 152 showed that aminosilicone macro emulsion (10% silicone in treatment solution) resulted in quite strong resistance to blue stain attack with both pre-weathered (1.2% staining of surface area) and not pre-weathered (0.2% staining of surface area) wood samples. Signs of blue staining were more evident on the pre-weathered samples which could be due to the break down of lignin, evident from the FTIR analysis. Blue stain development was evident by penetration of fungi through the ray cells visible in the cross sections of samples. Standard test for mould growth BS 3900 showed that wood treated with the aminosilicone macro emulsion (10% silicone in treatment solution) resulted in a delay and a certain degree of resistance to fungal growth on wood surfaces, whereas wood treated with the same concentration of quatsilicone micro emulsion and silicone macro emulsion with alkyl modified side group exhibited comparatively lower resistance.
S C Ghosh, C Mai, H Militz

Evaluation of the fire retardant efficacy and leach resistance of an amino resin fire retardant - Preliminary report
1983 - IRG/WP 3260
The Early Fire Hazard Indices of untreated Pinus radiata were determined by testing to Australian Standard 1530, Part 3 - 1976. Differences in the performance of heartwood and sapwood were noted, with heartwood samples giving higher Ignitability, Heat Evolved and Spread of Flame indices. The treatability of Pinus radiata with Pyrogard H was assessed, and backsawn sapwood treated more effectively than all other combinations of direction of cut and sapwood/heartwood. Treatment of kiln dried DAR Pinus radiata with Pyrogard H did not produce dimensional changes of practical significance. This factor, plus a high concentration gradient of retardant in the treated timber, make it an ideal treatment for fully machined and profiled Pinus radiata. The leach resistance of the retardant was assessed. A greater percentage of phosphorus than nitrogen was leached, but the retardant remaining after leaching conferred similar protection to the unleached material at equivalent rententions. Pyrogard H is an effective leach resistant fire retardant for Pinus radiata.
W D Gardner, P N Alexiou, P Lind, D Butler

Water-based silicones on wood
1997 - IRG/WP 97-30144
Five waterbased silicones commonly used on masonry where tested as water repellents for wood. The Water Repellent Effectiveness was determined by swellometer-tests and by measuring the water uptake of samples after 24 hours complete immersion and by immersion in a water level of 4 mm for 24 hours. The different methods are compared and discussed. Artificial and natural weathering was performed to determine the durability of the water repellency. Non of the tested silicones showed a significant ASE. The gluability of three tested silicones with PVAc gave poor results. One of the silicone microemulsions and one silicone emulsion performed a water repellency that might allow their use on wood. Two commercial non silicone water repellents that where tested as controls had a lack of durability after weathering.
D Lukowsky, R D Peek, A O Rapp

Feeding stimulants to enhance bait acceptance by Formosan termites
1994 - IRG/WP 94-10055
Four nitrogenous compounds were found to increase feeding by Coptotermes formosanus Shiraki in the laboratory. Cardboard disks dipped in urea solutions were consumed significantly more than untreated cardboard disks. Cardboard dipped in 8% urea showed a significant change in weight due to termite feeding over other urea treated cardboards. Examination of 15 amino acids in no choice feeding tests indicated that three, L-lysine, L-proline, and L-isoleucine, were feeding stimulants to Coptotermes formosanus. A fast screening method for feeding stimulant detectian was developed and is discussed. Using this method on 18 amino acids showed that L-proline and L-lysine were the best feeding stimulants.
G Henderson, M Kirby, J Chen

The potential of silicone-based formulations to enhance wood properties through industrial treatment for outdoor use
2011 - IRG/WP 11-30578
High hygroscopicity is one of the main weaknesses of wood as far as its susceptibility to biodegradation, and specifically to fungal decay. New wood preservation technologies are constantly entering the wood protection market, competing with traditional, biocide-based preservation. Silicones are commercially used as hydrophobic agents on stones and concrete. They belong to the restricted number of products that demonstrate a potential to protect wood through non-biocidal chemistry that increase its hydrophobicity. In this study, small Scots pine sapwood and beech specimens (Pinus sylvestris and Fagus sylvatica) were impregnated with silicone solutions in order to assess these solutions’ ability to increase wood hydrophobicity and resistance to fungal decay. Some wettability tests were also performed to gauge the difference in superficial tension of the tested impregnated wood pieces. The same tests also allowed us to determine the depth of the impregnation. The results of the relative water uptake and water repellent effectiveness tests showed that several silicone formulations significantly reduce the water content of wood by either filling the wooden cavities or impeding water absorption. The potential of using the tested silicone formulations to protect wood against decay fungi for outdoor applications is discussed in this paper.
F Simon, F Marchal, F Pochon, M Kutnik, I Le Bayon

Functional silicones used as a potential tool for the development of non-biocidal wood treatments
2015 - IRG/WP 15-30665
The increase of wood resistance against biological agents for outdoor use is conventionally performed by deep impregnation with preservatives. However, some of the traditional wood preservatives, used for decades for wood protection and regarded as the most effective, are currently subjected to severe restrictions because of their toxicity. In fact, new preservation technologies are constantly entering the wood protection market. Silicones are commercially used as hydrophobic agents in several industrial applications. In this study, small Scots pine (Pinus sylvestris) specimens were impregnated with silicone-based solutions and emulsions in order to increase wood hydrophobicity. Silicones used were previously functionalized with specific functions able to graft to the hydroxyl groups responsible for the wood hygroscopic nature. The silicones grafting on wood limit water uptake and their potential release to the environment. The results of the relative water uptake showed that several formulations significantly reduce the water content of wood by either filling wooden cavities or impeding water absorption. Silicones faintly functionalized present the better water uptake diminution while silicones with high functionalization level cannot reduce water uptake due to their hydrophilic character produced by the specific functions.
F Lhumeau, C Delaite, F Marchal, F Pochon, M Kutnik

Assessment of the biological durability of wood treated with organosilicon compounds
2016 - IRG/WP 16-30685
The European wood construction market is in need of environmentally friendly wood-based products whose service life meets the expectations of end users. Non-biocidal silicon-based water repellents, which can be applied to different materials, help minimize their vulnerability/susceptibility to liquid water. Consequently, they have the potential of increasing wood’s resistance against decay fungi by reducing their ability to absorb water. Moreover, by filling the pores of wood, they may reduce its vulnerability to wood-boring insects and thus improve its durability. In order to determine their suitability as wood protectors, three silicon-based water repellents were applied at different concentrations to samples of Scots pine, beech and oak. The application was either superficial (dipping) or by deep (vacuum impregnation). Durability tests were then performed in order to determine the resistance of the treated wood samples against moulds, blue stain and basidiomycete decay fungi, as well as against Reticulitermes subterranean termites. Additionally, eco-toxicological tests were run in order to select the product which had the least environmental impact. The results demonstrate that the three tested organosilicons exhibit different levels of toxicity and improvement of the resistance of the tested wood species against biological threats. The anti-fungal resistance is lower than that provided by traditional biocidal wood-preservatives, but it is still adequate in applications where short-to-average service-life is acceptable and where maintenance and/or replacement is possible. Termite behaviour and feeding preferences in situations where choosing between treated and untreated wood was possible demonstrated that insects tend to avoid consuming wood specimens impregnated with organosilicons. Wood-based materials with levels of biological resistance which are intermediate between wood’s natural (inherent) resistance and that improved with the help of biocides as well as wood-protection products and processes which allow reaching these levels should be appreciated more. They increase the range of possible end-uses for wooden commodities made of European non-durable wood species such as Scots pine and beech both with regard to the material’s properties and its expected performance.
M Kutnik, M Montibus, S Derocker, S Salivati, J-P Lecomte

Functional silicones used for wood protection: preliminary study
2017 - IRG/WP 17-30720
Due to worldwide regulation the wood preservation domain is constantly changing. Silicones are used for different industrial applications as hydrophobic agents. This property could enable to reduce water uptake of wood treated with these compounds. Treated wood could then be less prone to dimensional variation and fungal attack, those parameters being driven by variations in wood’s moisture content. In the present study, Scots pine specimens were treated with different silicone-based products, either separately or in combination. The aim of combining silicones was to create a hydrophobic network protecting the surface of wood from water ingress and fungal attack. In addition to fungal resistance and dimensional stability, protection against wood boring insects is required for most applications. Nevertheless silicones used in this study did not demonstrate any ability to protect wood against insects. Consequently, permethrin at different concentrations was combined to the first silicone. Water uptake, resistance against Reticulitermes termite, longhorn beetle Hylotrupes Bajulus and basidiomycete fungi were evaluated after treatment of Scots pine with the different formulations of silicones. Resistance against insects and fungal decay was successfully improved for Scots pine treated with different silicones and water uptake was decreased. In addition, silicones applied to wood demonstrated limited leachability over time, supporting possible use for outdoor applications. The tested silicone-based formulations, containing only an insecticide but protecting wood both against insects and fungi, could be regarded as a more environmentally friendly alternative to traditional wood preservatives, which contains both insecticides and fungicides.
C Reynaud, F Marchal, F Pochon, M Kutnik

The Study of the Preparation of Overlaid MDF with the Flame Retardant Impregnated Paper
2018 - IRG/WP 18-40848
The preparation of overlaid medium density fiberboard (MDF) was studied. The flame retardant impregnated papers (FRIP) were overlaid on the surface of the MDF for the fire protection. The results showed that: 1) The production of the FRIP was based on the technology of melamine-impregnated paper, which required the viscosity of the impregnated resin lower than 20s. However, with the addition of the pentaerythritol (PER), one component of the flame retardant, the viscosity of the resin increased rapidly because of H-bonds. The viscosity of the resin was kept low by addition of urea. 2) The curing time of the resin was adjusted by the ratio of F/(M+U) and the addition of ammonium polyphosphate. 3) The surface bond strength of the FRIP met the standard requirements, which was influenced by the pressing conditions. 4) The flame retardant was concentrated on the surface of wood materials with the FRIP. The efficiency of the flame retardant was enhanced significantly, and better than that of the physical mixture and impregnation, and the cost was reduced.
W Qu, M Wu, Y-Z Wu

A novel wood preservation technology improving durability and water-related properties
2022 - IRG/WP 22-40926
A newly developed silicone oil (Archroma Management GmbH, Switzerland) was tested for wood modification purposes. Scots pine sapwood was treated with aqueous solutions of this silicone oil and showed a penetration of the modification agent into the wood cell wall. Both, biological durability and moisture-related properties, experienced significant improvements by the modification. Besides, the modification generated a significantly improved weathering performance of wood during outdoor exposure. The molecules of the silicone oil formulation can be fixated inside the wood cell wall by drying the impregnated wood blocks at temperatures < 80 °C. Thus, this technology differs significantly to existing cell wall penetrating wood modification technologies, which necessitate a high temperature curing (> 100 °C) for a proper fixation of the modification agent inside the wood matrix. By that, the presented silicone oil treatment shows high potential for an implementation in impregnation and drying plants, which at present exist and operate in the wood preservative and wood processing industry. For this reason, the technological simplicity eliminates technological and financial hurdles, which most of the existing chemical wood modification technologies suffer and may speed up an implementation of this technology on an industrial scale.
L Emmerich, H Militz, M Vila