Artificial and natural weathering treatments have been shown to influence the chemical and physical properties of wood and wood-based materials, e.g. moisture content, density, composition and ...coloration. Changes in color caused by natural and artificial sources of ultraviolet radiation (UV) are an important topic to be studied in wood, and have been addressed in this work for eight strength classes of timber species (hardwoods and softwoods). Color measurements were carried out according to ABNT NBR 7190:1997 normative document by the CIE-L*a*b* (CIELAB) system, with L* representing lightness, and a* and b*, red/green and yellow/blue coordinates, respectively. For the samples studied herein, a* and b* approached zero after exposure to artificial UV radiation, when a gray tonality was noticed in dark-colored surfaces. Naturally weathered samples, on the other hand, responded more effectively to long-term UV exposure (360 days) for all color-space parameters, both hardwoods and softwoods. This implies that effects of air pollution and other degradation-aging factors need to be considered. Results of statistical analysis also contributed to quantify changes in color after artificial and natural weathering treatments.
•Considerable changes in color caused by natural and artificial UV sources.•Complete analysis of changes in color for eight strength classes of timbers.•Natural, long-term aging caused changes in all color-space parameters in woods.•Changes in color distinguish weathered softwoods and hardwoods from certified forests.
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•The transparent coatings can bond wood firmly.•Maintaining the natural beauty of wood texture.•Samples have the remarkable thermoresponsive behaviour.•Surface properties of modified ...wood changed from hydrophilic to hydrophobic.•Spherical particles were neatly arranged in the surface coating of modified wood.
The smart reversible thermoresponsive wood with hydrophobic performance was fabricated by depositing modified thermoresponsive coatings on wood surfaces. The modified composite films were prepared by entrapping thermochromic materials (TM) supported on the 3-Aminopropyltriethoxysilane (AEPT) into polyvinyl alcohol solution (PVA). All the samples possessed superior reversible thermoresponsive property, and the thermochromic response rate of TM-APTES/PVA modified wood was higher than the other samples. The attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) spectra demonstrated that the TM-APTES/PVA composite polymer films have been successfully settled onto wood surfaces. The scanning electron microscope (SEM) and pull-off test results proved that the modified wood possessed better dispersion stability of TM particles and stronger interfacial adhesion than TM/PVA coated wood. Furthermore, the surface properties of wood materials changed from hydrophilic to hydrophobic after chemical modification.
The effect of UV–visible light irradiation on the changes in colour and chemical composition of the surfaces of
Pinus roxburghii (chir pine, a softwood) and
Hevea brasiliensis (rubber wood, a ...hardwood) was studied. Analysis of colour changes in wood surfaces during photodegradation was carried out by measuring CIELAB parameters (
L*,
a*,
b* and Δ
E*). FTIR and fluorescence spectroscopy were used to study chemical changes caused by irradiation. Irradiation modified physical and chemical characteristics of wood surfaces and resulted in rapid colour changes, degradation of lignin and increased concentration of chromophoric groups on the wood surfaces. Overall, colour changes (Δ
E* values) correlate well with degradation of lignin and relative increase in the concentration of carbonyl groups determined by FTIR measurements. Fluorescence emission spectra measured from unexposed wood surfaces show excitation wavelength dependence. Photo-irradiation leads to a rapid reduction in the emission intensity, broadening of spectra and a significant red shift in the fluorescence emission maximum. Fluorescence quenching is related to the carbonyl formation.
•A novel nanoplate-like tungsten trioxide was grown on a wood substrate.•The obtained product responded to ultraviolet radiation very intensively.•The product had the superhydrophobic performance ...after OTS treatment.
A novel nanoplate-like tungsten trioxide was grown on a wood substrate using a facile one-step ethanol-assisted hydrothermal method. The morphology, chemical composition, crystalline structure, optical properties, thermostability, wettability and roughness of the WO3-treated woods were investigated. The results showed that the uniform WO3 nano-plates exhibited an edge length of 1553nm and a thickness of 102nm. These structures were observed to be highly crystallized with hexagonal structures. The X-ray photoelectron spectroscopy (XPS) and Raman spectrum (RS) analysis demonstrated that the pure WO3, without other impurities, could be grown on a wood substrate. The as-obtained product appeared a remarkable blue shift than the pristine wood by UV–vis analysis and had an obvious color response to UV light irradiation at 365nm. The thermogravimetry (TG) analysis showed that the maximum degradation rate of the WO3-treated wood exhibited slower degradation rates when compared to the native wood control. Through the octadecyltrichlorosilane (OTS) treatment, the as-fabricated product exhibited a water contact angle (WCA) of 152°, indicative of its superhydrophobic property, which was ascribed to the low surface energy of OTS and the large surface roughness of the product.
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A detailed study of early colour change in Scots pine (
Pinus sylvestris) due to accelerated simulated sunlight exposure was undertaken focusing on the first 24 h of change. Colour changes were ...monitored with a Datacolor check spectrophotometer and compared with a set of controls. Measurements on both samples and controls were performed hourly for the first 24 h and there after daily until 168 h’ exposure with extra measurements at 200, 350 and 500 h. A subset of samples was extracted prior to exposure to check the effects of any colour change due to the presence of extractives. Data was analysed using the reflectance spectra (400–700 nm) as well as the CIE-
L
∗
a
∗
b
∗ system and Δ
E. The majority of colour changes were found to occur within the first 24 h. This was unaffected by the removal of extractives from the wood and was independent of temperature. Mechanical properties and weight changes were also monitored to allow a comparison of sensitivity between the differing methods.
Some wood species have antimicrobial properties, making them a better choice over inert surfaces in certain circumstances. However, the organic and porous nature of wood raises questions regarding ...the use of this material in hygienically important places. Therefore, it is reasonable to investigate the microbial survival and the antimicrobial potential of wood via a variety of methods. Based on the available literature, this review classifies previously used methods into two broad categories: one category tests wood material by direct bacterial contact, and the other tests the action of molecules previously extracted from wood on bacteria and fungi. This article discusses the suitability of these methods to wood materials and exposes knowledge gaps that can be used to guide future research. This information is intended to help the researchers and field experts to select suitable methods for testing the hygienic safety and antimicrobial properties of wood materials.
The surface temperature of a drying wooden board is strongly related to the drying process. However, it is relatively difficult to determine the surface temperature accurately during drying. In this ...paper, an experimental setup for analyzing the wood surface during drying by thermal imaging as well as dry and wet-bulb temperature reference surfaces was tested. Spruce sapwood samples were dried in various climates and evaluated with respect to both mass loss and surface temperature. The experimental setup enabled both qualitative and quantitative analysis of the wood drying process. The results showed that thermal imaging enabled a detailed view of the drying progression. The distinct correlation between surface temperature and mass change showed that an accurate determination of a basic, often considered, and difficult-to-determine drying potential is possible.
KEY MESSAGE : Visual aspects of wood are appreciated in interior design and many other high-end applications. This study focuses on consumer preferences which are examined regarding visually ...different spruce floor samples. Results indicate specific market segments according to different consumer preference groups. CONTEXT : Wood for interior use is attractive to many consumers for aesthetic and ecological reasons. Visual attractiveness can be decisive for high added value. Industrial wood grading based on technical parameters is a common practice, but little is known about consumer preferences which could direct the production chain from the tree to the final product presented to the consumer. AIMS : In this study, two objectives are addressed: (1) reducing the complexity of wood appearances based on consumers’ perceptions and (2) aggregating diverging preferences to consumer groups. METHODS : Four hundred twenty-five boards from spruce logs were classified on the basis of their visual appearance. Fifteen visual classes of these boards were identified. From each of these classes, a representative floor sample was made with dimensions of 2 m × 1 m and a high-resolution image taken of it. These 15 images were then evaluated by consumers and grouped using multidimensional scaling. Finally, consumer preference profiles were analysed on the basis of latent class analysis. RESULTS : The first main result is that from the initial 15 classes which arose from the visual board sorting, consumers could objectively only distinguish seven from each other. The second main result is that among these seven classes, five of them were identified as the most liked. CONCLUSION : This contribution provides an objective methodology for the assessment of the visual preference of wooden products that may pave the avenue to more efficient allocation of the selected end products to the targeted groups of consumers.
Yeast adhesion to and biofilm formation on surfaces is present in many different environments. In food industry, biofilms may be a source of contaminations, causing food spoilage and reducing quality ...of products.
and
are two common yeast genera involved in the spoilage of some food products. The aim of this study is to assess the potential of
and
species to adhere to two types of wooden surfaces (smooth and rough), one of the materials typical for the food processing industry, and investigate the influence of surface roughness of wood on the degree of yeast adhesion. The adhesion of the cells to the wooden surfaces was determined by rinsing them from the surface, followed by methylene blue staining, and quantification after imaging under microscope by automatic counting of viable cells. The results showed that all
and
strains were able to adhere to the wooden surfaces in a species- and strain-dependent manner. On the other hand, our data indicated that adhesion by these yeasts was not significantly affected by the roughness of the wood surfaces.
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