Application of Waterborne Acrylic and Solvent-Borne Polyester Coatings on Plasma-Treated Fir (Abies alba M.) Wood

This research investigates the effect of plasma treatment with air, nitrogen (N2), and carbon dioxide (CO2) gases on the performance of waterborne (acrylic) and solvent-borne (polyester) coated fir (Abies alba M.) wood samples. The properties of the plasma-coated samples were analyzed before and after exposure to accelerated weathering and compared with those of untreated and solely treated ones. According to pull-off testing, the coating adhesion of the wood samples was considerably improved by plasma treatment, and obvious differences were observed between different plasma gases. The effect was more pronounced after the weathering test. Similar results were obtained for the abrasion resistance of the samples. The water contact angle measurement illustrated more hydrophilic character in the solely plasma-treated wood in comparison with the untreated wood. The application of coatings, however, strongly improved its hydrophobic character. The performances of waterborne and solvent-borne coatings on plasma-treated wood were comparable, although slightly better values were obtained by the waterborne system. Our results exhibit the positive effect of plasma treatment on coating performances and the increased weather resistance of the waterborne and solvent-borne coating systems on plasma-treated wood.

The Influence of Freezing and Thawing Process on the Bending Moment Capacity of L-Shaped Heat-Treated Wood Dowel Joints

In this work, the influence of the freezing and thawing process on the bending moment capacity of L-shaped heat-treated wood dowel joints is analysed. The parts of the joints were made of heat-treated ash (Fraxinus excelsior) wood. Half of the analysed joints were randomly divided in two groups. One group was frozen and thawed in a climatic chamber and the other group was kept in laboratory environmental conditions. The bending moment capacity was calculated by means of ultimate failure load, which was experimentally obtained. One-way analysis of variance (One-way ANOVA) was applied to figure out if there is a significant difference between the analysed groups. Based on the obtained results, it was concluded that the freezing and thawing process did not significantly affect the strength of the L-shaped heat-treated wood dowel joints.

Surface and Physical Features of Thermo-Mechanically Modified Iroko and Tauari Wood for Flooring Application

The aim of the study was to determine the selected surface and physical properties of iroko (Milicia excelsa (Welw.) C.C. Berg) and tauari (Couratari spp.) wood after thermo-mechanical treatment (TMT) in relation to extractive content. During TMT, no chemicals are introduced into the wood, which distinguishes this method from a number of wood modification methods. The iroko and tauari wood were subjected to volumetric densification in a hydraulic press. The wood was densified in a radial direction at a temperature of 100 and 150 °C. The wood color parameters were measured using the mathematical CIE L*a*b* and L*C*h color space models. The roughness parameters of Ra and Rz parallel and perpendicular to the grain were investigated. The contact angle (CA) of the wood with distilled water was determined based on the sessile drop method. The equilibrium moisture content (EMC) and dimensional changes of the wood were determined for a climate with a temperature of 20 °C and a relative humidity (RH) of 9%, 34%, 55%, 75% and 98%. The tauari wood was less prone to color changes under the influence of TMT than the iroko wood. After densification, the iroko and tauari wood displayed a different character of roughness changes. The iroko wood featured the lowest level of roughness after TMT at 100 °C, and the tauari wood after TMT at 150 °C. The densified iroko and tauari wood were characterized by weaker dynamics in the changes in their respective contact angles than the non-densified wood. The higher the temperature of the TMT, the lower the EMC of the wood. Higher EMC values were observed for the tauari wood than for the iroko wood. This was due to the lower content of chloroform-ethanol extractives. Similar dependencies were obtained in the case of hot water extractives. The thermo-mechanically treated wood displayed a greater tendency towards dimensional changes in a climate with high relative air humidity, i.e., above 70%, compared to the non-modified wood.

Potential new tracers and their mass fraction in the emitted PM₁₀ from the burning of household waste in stoves

The production and use of plastics is increasing rapidly as they are widely used in packaging, construction materials, furniture, foils, etc. As a consequence of their widespread use and often disposable nature, vast streams of plastic waste are continuously generated, a considerable fraction of which are combusted in households worldwide. In this paper, various types of commonly used plastics (PE, PET, PP, PU, PVC, PS, ABS) as well as treated wood samples (LDF, low-density fibreboard) and firewood were combusted separately in a test stove under controlled conditions. The particulates emitted during the combustion test were collected on filters, potential tracers for each waste type were identified by GC-MS, and their relative abundances were determined. The emission factor of 1,3,5-triphenylbenzene was found to be higher for polymers containing aromatic rings in their structure. The application of terphenyls and quaterphenyls as tracer compounds has also been investigated. The trimer of styrene was found to be a potential tracer for the combustion of polystyrene and/or styrene-containing copolymers. Novel tracers were proposed for the burning of PET and furniture plates (LDF), which are among the most widely used waste types burned in households.

Effects of various artificial agarwood-induction techniques on the metabolome of Aquilaria sinensis

Background Agarwood is a highly sought-after resinous wood for uses in medicine, incense, and perfume production. To overcome challenges associated with agarwood production in Aquilaria sinensis, several artificial agarwood-induction treatments have been developed. However, the effects of these techniques on the metabolome of the treated wood samples are unknown. Therefore, the present study was conducted to evaluate the effects of four treatments: fire drill treatment (F), fire drill + brine treatment (FS), cold drill treatment (D) and cold drill + brine treatment (DS)) on ethanol-extracted oil content and metabolome profiles of treated wood samples from A. sinensis. Results The ethanol-extracted oil content obtained from the four treatments differed significantly (F < D < DS < FS). A total of 712 metabolites composed mostly of alkaloids, amino acids and derivatives, flavonoids, lipids, phenolic acids, organic acids, nucleotides and derivatives, and terpenoids were detected. In pairwise comparisons, 302, 155, 271 and 363 differentially accumulated metabolites (DAM) were detected in F_vs_FS, D_vs_DS, F_vs_D and FS_vs_DS, respectively. The DAMs were enriched in flavonoid/flavone and flavonol biosynthesis, sesquiterpenoid and triterpenoid biosynthesis. Generally, addition of brine to either fire or cold drill treatments reduced the abundance of most of the metabolites. Conclusion The results from this study offer valuable insights into synthetically-induced agarwood production in A. sinensis.

Local force titration of wood surfaces by chemical force microscopy

Chemical force microcopy, a variation of atomic force microscopy, opened the door to visualize chemical nano-properties of various materials in their natural state. The key function of this method is given by translating adhesion forces between a functionalized tip and the sample to chemical surface behavior. In force titration, these adhesion forces are studied in different pH buffers, which allows estimating the pKa value of the analyzed surface. Herein, we report the use of this method to study natural and chemically treated wood surfaces, which are of interest in sustainable material design. First, we show varying adhesion phenomena of OH- and COOH-functionalized tips on native spruce wood cells. Then, we demonstrate how peak force tapping with chemically functionalized tips can be used to estimate the pKa value of gold substrates (pKa ≈ 5.2) and different wood cell wall layers with high spatial resolution. Additionally, the swelling behavior of wood samples is analyzed in varying pH buffers. With the applied method, chemical surface properties of complex natural substrates can be analyzed. Graphical abstract

Chemical and Microbial Analysis of Bedding Material (Wood Shavings) Treated with Graded Levels of Aluminium Sulphate (Alum)

The study was carried out at the poultry unit of the Department of Animal Science teaching and research farm, Ahmadu Bello University, Zaria to determine the chemical and microbial analysis of poultry litter (wood shavings) treated with graded levels of alum. The alum used was obtained from the Sabon-gari market in Zaria, Kaduna State. The rates of alum application (prior to keeping the birds) was as follows: T1 control (normal wood shavings with no alum), T2 (5% alum by kg weight of wood shavings), T3 (10% alum by kg weight of wood shavings) and T4 (15% alum by kg weight of wood shavings). Five sets of litter samples were obtained fortnightly from each pen from different locations i.e. the four corners and center from which the microbial load, pH, total nitrogen (N), soluble reactive phosphorus, VFA and NH4+ concentration were measured. The result shows significantly (P<0.05) lower pH value in all the alum treated wood shavings groups (5%, 10% and 15% alum treated wood shavings) compared to the control. The result showed that significantly (P<0.05) lower total volatile fatty acid level was obtained in all the alum treated wood shavings groups (5%, 10% and 15% alum treated wood shavings) compared to the control untreated wood shaving group. The results showed a decrease in total bacteria, E. coli and Salmonella spp. load in alum treated wood shavings groups (5%, 10% and 15% alum treated wood shavings) compared to the control, while mould and yeast load was increased in all the alum treated wood shavings groups (5%, 10% and 15% alum treated wood shavings) compared to the control. The study conclude that treating wood shavings with alum can reduce microbial load of the litter, hence improve health and reduce mortality. Treating wood shavings with alum tends reduce the microbial load of the litter.

Comparison of durability of treated wood using stake tests and survival analysis

The stake test is widely used to evaluate the efficacy of wood preservatives. This test monitors the deterioration level observed in treated stakes partially inserted into the ground. The results are conventionally expressed as the relationship between deterioration levels and exposure periods. The preservative efficacy is compared among the stake groups treated with different retention levels based on the test results; however, there is no scientific basis for the comparison. We applied survival analysis to the conventional stake test to include a scientific basis to the test. Stakes impregnated with different types and retention levels of preservatives were subjected to deterioration at two test sites for approximately 30 years. The deterioration levels were monitored according to the conventional procedure and survival analysis was applied to the monitored data. Kaplan–Meier plots of the survival probabilities against the exposure periods indicated that there is a significant difference between the durability of the stakes treated with alkylammonium chloride (AAC-1) at K2 and K3 retention levels, whereas no significant difference was observed between those at K3 and K4 retention levels. Contrastingly, emulsified copper naphthenate (NCU-E) was found to be a reliable preservative, and the stakes impregnated with NCU-E showed a significant increase in durability in accordance with preservative retention. Alkaline copper quaternary (ACQ-1) also appeared to be a reliable preservative; however, the increase in stake durability after ACQ-1 treatment differed between the test sites. These results were verified using the modified Gehan–Breslow–Wilcoxon test with Holm’s p adjusting method.