Radiata Pine Wood Treated with Copper Nanoparticles: Leaching Analysis and Fungal Degradation

Radiata pine is the main wood species used in the Chilean construction industry, but it must be protected due to its low natural durability. Chemical protection of wood by impregnation allows for a more efficient utilization of the forest resources by extending its useful life. The use of nanoparticles in wood protection has garnered great interest during the last decade, due to their unique physicochemical properties, different from those of larger sized materials. In this research, the impregnation of radiata pine wood with copper nanoparticles (CuNP) was studied in terms of retention, penetration, leaching, and its protective effect against wood rot fungi growth according to EN 113, AWPA A3-91, A9-18, and E11-16. Penetration analysis confirmed a uniform distribution across the wood, with total penetration in the impregnated samples with the highest concentration solution of CuNP. Retention values of the impregnated wood increased proportionally with the concentration of nanoparticles evaluated by EDXRF. Leaching analysis showed copper removal during the first hours of the test, with a constant leaching rate up to 144 h. Impregnated wood mass loss (ML) due to exposure to Gloeophyllum trabeum and Rhodonia placenta fungi were significantly reduced regardless of the CuNP concentration or fungi tested, with an ML smaller than 5% and smaller than 14% for leached samples.

Production of Agarwood Resin in Aquilaria beccariana Using Inducement Technology

Agarwood is a type of resin impregnated wood produced from the wounded Aquilaria trees. This agarwood gives a pleasant fragrant when it is burned. It becomes high-priced and increase demanded in the world due to the depletion of wild agarwood in the forest caused by illegal poaching activities. Agarwood resin can only be produced by injuring caused by lightning or wounded by animals under natural conditions. However, the natural process of resin accumulation is uncertain and time-consuming. Therefore, we developed an agarwood inducement technique that served as the alternative way to induce the agarwood formation in a short time. Three inducement techniques, including the injecting method, knocking method and combination of injecting & knocking method were applied to induce resin formation. In this study, we evaluated the technique for producing agarwood in species Aquilaria beccariana, which is native and only can be found in Borneo Malaysia. For A. beccariana trees treated with the inducement technique, resin formed and spread throughout the cell in the trunk. The evaluation results showed that the agarwood yield per tree reached around 5 to 7 kilogram. Furthermore, this agarwood derived from the induction was found to have a similar quality with the wild agarwood. This indicates the inducement technology had successfully produced agarwood resin in A. beccariana with a grade similar to the wild agarwood.

Influence of Soil Characteristics on Wood Biodeterioration by Brown Rot Fungi

Soil conditions can directly influence the inoculum potential of wood decay fungi, which is likely to be a major factor in the premature failure of utility poles across Europe. The objective of our study was to assess the influence of soil pH, humic acid and iron on wood decay. For this purpose, we incubated Fe-impregnated wood specimens on artificial medium to evaluate the influence of the metal on the activity of brown rot fungi. Moreover, the impact of Cu-leaching from impregnated wood specimens that were exposed to humic acid solutions was measured. In addition, weight losses caused by brown rot fungi in impregnated wood pole segments and stiffness (Young’s modulus of Elasticity) of Cu-impregnated wood specimens were quantified. The pH measurements showed that the soil samples were slightly acid (pH = 6.7 ± 0.7). In comparison to non-impregnated controls, the Fe-impregnated samples significantly increased weight losses by brown rot fungi (>30–40%). In the presence of humic acid the release of copper from chromium-free wood preservatives (up to 143.34 mg L−1) was enhanced. Weight losses in impregnated wood segments by brown rot fungi ranged from 5.3 to 20.4%. The recorded reduction in stiffness by brown rot fungi ranged from approximately 3.96 to 55.52% for Cu-impregnated wood specimens after 12 weeks. Our study shows that the pH, humic acid, iron content and selected wood preservatives greatly influence susceptibility of impregnated wood to brown rot fungi during ground contact.

Mechanical Properties and Strength Reliability of Impregnated Wood after High Temperature Conditions

The paper presents the results of the research into the impact of impregnation of wood on its bending strength and elastic modulus under normal conditions and after thermal treatment and investigates its structural reliability. Pinewood, non-impregnated and pressure impregnated with a solution with SiO2 nanoparticles, was used in this research. The use of nanoparticles decreases the flammability of timber among others. Some of the tested samples were treated at 250 °C. This temperature corresponds to the boundary of the self-ignition of wood. This elevated temperature was assumed to be reached by a given speed of heating within 10 min, and then the samples were stored in these conditions for 10 and 20 min. The tests demonstrate that the bending strength of the impregnated wood was slightly improved, the impregnation did not impact the elastic modulus of the material in all such conditions, and the residual strength decreased less for the wood impregnated after being exposed to the elevated temperatures. The reliability analysis proves a positive effect of impregnation with a solution with SiO2 on the durability of wood, both after being exposed to normal and elevated temperatures. The distribution of the failure rates indicates a more intensive degradation of non-impregnated wood. The distribution of the survival function demonstrates a more probable non-destruction of impregnated wood after elevated temperature conditions.

Thermal insulation and hydrophobization of wood impregnated with silica aerogel powder

The aim of the study was to develop a simple and cost-effective method to improve thermal insulation and hydrophobicity of wood. Herein, we attempted to use commercially available silica aerogel powders suspended in ethanol to treat the wood by a simple vacuum impregnation process. The effects of particle size (20 µm and 40 nm) of silica aerogels and the number of impregnation cycles (1, 3, and 5 cycles) were examined on the thermal conductivity and the surface hydrophobicity. The results showed that the thermal conductivity of silica aerogel-impregnated wood decreased by approximately 38%. The water contact angle of the impregnated wood increased up to the maximum values 153° with a comparison with 80° of the untreated wood, indicating effective hydrophobization after silica aerogel impregnation. The tensile properties of the impregnated wood were found slightly improved. The results indicate that the impregnation of silica aerogel powders in wood can be a facile and efficient approach to prepare wood with thermal insulation and hydrophobicity, which may hold great promise to be employed in manufacturing wood-based materials used in interior decoration and buildings.

DEVELOPMENT OF A COMPOSITIONAL MODIFIER FOR MODIFICATION OF WOOD BY SPECIFIED PROPERTIES

In recent years, the production of modified wood has been actively developing abroad. This article discusses the composition of a complex modifier for modified wood, which will improve the performance of friction units with bearings made of modified wood by reducing intermolecular interactions between contacting bodies, increase dimensional stability and hardness of modified wood, and will also comply with environmental requirements. The density of the liquid components of the impregnating compositions was determined. The number of components necessary for the preparation of impregnating compositions was calculated. The impregnation technology is as follows: the impregnating composition is poured into a tin can, heated on an electric stove to 120 0C. Prepared (dried, weighed, measured on three sides and marked) samples of 15 pieces in each impregnating composition are immersed in a hot impregnating solution. Tin cans with samples are placed in a pre-heated autoclave, closed, and brought to a pressure of 40 atm. At this pressure, the samples are kept for 5 minutes. Then the pressure is brought to atmospheric pressure, the samples are removed, dried with filter paper and placed in a desiccator for cooling to a temperature of 20 ± 2 0С. After cooling, the samples are weighed on an analytical balance to the nearest 0.002 g and the three sides of the sample are measured with a caliper. The quality of impregnation of the samples was determined. Water absorption, moisture absorption, linear swelling of the samples of impregnated wood were determined.