Characterization of a formaldehyde-free cornstarch-tannin wood adhesive for interior plywood

This study investigated the physical properties (rheological and thermogravimetric analysis) of cornstarch-tannin adhesives and the mechanical properties (dry tensile strength and 3-point bending strength) of plywood made using cornstarch-tannin adhesives. This adhesive was evaluated for its utility in interior plywood manufacture. The optimum cure temperature and cure time of cornstarch-tannin adhesives were 170°C and 4?min, respectively. Plywood bonded with formaldehyde-free cornstarch-tannin adhesive exhibited excellent mechanical properties comparable to commercially available phenol-formaldehyde plywood adhesives. It was found that cornstarch-tannin panels which do not contain formaldehyde and with an emission equal to that of heated but unbound wood can be obtained by the use of hexamethylenetetramine (hexamine) as hardener. The work has indicated that an environmentally friendly wood adhesive can be prepared from a natural renewable resource (cornstarch and wattle tannin) for bonding interior-type plywood.     

Hydroxymethylated resorcinol (HMR) priming agent for improved bondability of silicone modified wood glued with a polyvinyl acetate adhesive

A hydroxymethylated resorcinol (HMR) was used as a coupling agent to improve glueability of silicone (aminofunctional polydimethylsiloxane) modified pine sapwood (Pinus sylvestris) with polyvinyl acetate (PVAc). Priming with HMR did not significantly increase tensile shear strength of unmodified and silicone treated wood under dry conditions. Under wet conditions, tensile shear strength of the control specimens was increased by 37% and of the silicone modified specimens by 13%. Despite of higher shear strength under wet conditions, the primed silicone treated specimens displayed lower degree of wood failure than the unprimed treated specimens.     

Development and production of a new type of thin compact Siro-fil worsted fabric北大核心

According to the market demands of high quality, thin and light, natural fiber fabric, with natural fiber as raw material, combined with the unique advantage of Siro-fil yarn, we design and develop a light-weight worsted fabrics. According to the characteristics of raw materials and product requirements, from raw material selection, spinning, weaving process and post finishing aspects, it respectively introduces the production process and key points of product formation. The type of thin compact Siro-fil worsted fabric has the style of elegant, lively hand, good elastic characteristics. The product can be used as a men's and women's shirt fabric, and has broad market prospects.     

Use of wax emulsions for improvement of wood durability and sorption properties

Waxes are used for treatment of wood surfaces for several decades predominately as surface treatments because they weakly penetrate into the wood. In order to overcome this issue, water emulsions were applied in the present experiment. Five water emulsions of various concentrations were used, namely montan wax, polyethylene, ethylene copolymer and oxidized polyethylene wax. Performance of wax treated beech (Fagus sylvatica) and Norway spruce (Picea abies) against white rot, brown rot and blue stain fungi was tested. In parallel, sorption properties of wax treated wood were determined. The treated specimens were more resistant to wood decay fungi. Polyethylene and oxidized polyethylene wax were found to be particularly efficient. Although this treatment does not improve resistance to blue stain fungi, it reduces the sorption of water.     

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.     

Development of a novel fa?ade sandwich panel with low-density wood fibres core and wood-based panels as faces

The paper explores, experimentally and theoretically, the possibility of producing a novel cladding sandwich panel comprised of a low-density wood fiber (WF) core and faces made of wood-based panels. Tests on small specimens, using physical and optical devices, were performed for the basic mechanical characterization of WF. Shear modulus (G) was the main target; and values for a range of nominal densities (??) from 110 to 190?kg/m³ were obtained. Short term load tests on real scale WF sandwich (WFS) specimens of 3.2?m span were also performed. An initial simple analytical structural linear model, taking into account the shear deformation of the core, was used to evaluate the data obtaining a reasonable agreement. The results show that WFSs are a viable solution at least for claddings; special care must be taken, however, in the selection of the face panels due to the influence of hygro-thermal changes. The line of work is especially attractive as WF is a natural and sustainable product.     

Effect of layers relative moisture content on the IB strength of pine tannin bonded particleboard

Relative percentage of moisture content of surface and core layers in pine tannin-bonded particleboard influences markedly the internal bond (IB) strength of the board. This is due to the differential compression exercised on the layers related to their moisture content. The moisture content differential between surface and core layers in particleboard during pressing is a determining parameter for the internal bond (IB) strength of particleboard. In the case of tannin adhesives where these differences can be more pronounced than for synthetic adhesive the effect is more easily observable.     

The significance of lap-shear testing of wood adhesive bonds by means of Volkersen’s shear lag model

Lap-shear specimens of varying geometry were bonded with two different adhesives and tested. At the same time, the stress distribution along the adhesive bond lines of the examined specimens was modelled by means of Volkersen’s equation. A good agreement was found between apparent shear strength and a stress concentration factor derived from the model. Highly significant effects of adhesive stiffness were found at short overlap length and high specimen thickness.     

Longitudinal penetration of silicon dioxide nanosols in wood of Pinus sylvestris

For purposes of wood preservation, stabilization and fire protection, the penetration ability of bio-inspired environmentally friendly Sebosil^® nanosols in axial direction of the pine tracheids were investigated using macroscopic evaluations and EDX microanalysis.     

Preparation and characterization of urea–formaldehyde adhesives modified with glyoxalated tannin

European Journal of Wood and Wood Products - Urea–formaldehyde (UF) resins are the most important type of adhesive for the preparation of wood-based panels, due to its good performance and...     

Microwave testing of moist and oven-dry wood to evaluate grain angle,density, moisture content and the dielectric constant of spruce from 8 GHz to 12 GHz

The scope of this work is to discuss the challenges and demonstrate the potential of microwave testing for applications in the wood processing industry. Microwave technology benefits from the anisotropic dielectric properties of wood to simultaneously identify grain angle, density, and moisture content of wood. Therefore, the theory of free space transmission measurement is thoroughly discussed with emphasis on the characteristics of (and how to deal with) reflections occurring in real measurements. A more sophisticated calculation method for the derivation of the desired physical wood properties is presented. The advantages of a modern laboratory style setup are shown and its possible transition in an industrial-style application is discussed. Moist (moisture content 7.6–14%) and oven-dry spruce samples are tested. The detection of grain angle for moist and oven-dry wood yields an RMSE (root-mean-squared-error) of 0.14° and 0.4°, respectively. Moisture content is evaluated with density- and thickness-independent methods. Adapted regression models are proposed yielding an RMSE for moisture content of 0.45% for a single frequency measurement. The promising advantages of wood moisture estimation with frequency sweeps instead of fixed frequency signals are discussed and demonstrated for all samples (RMSE 0.39%). The dielectric constant of moist and oven dry spruce in the range from 8 to 12 GHz is evaluated in respect to density, moisture content and temperature. The respective constants ε′, ε′′, and tan(δ) are formulated in a general form via a non-linear regression and compared to existing data in literature.     

The β-lactoglobulin content of bovine milk: Development and application of a biosensor immunoassay

An optical biosensor immunoassay exploiting surface plasmon resonance is described for the quantification of β-lactoglobulin in milk. Samples were diluted with buffer, and the protein estimated from binding with a polyclonal antibody immobilised on the sensor surface. Analytical method performance characteristics including range, detection limit, precision and accuracy were determined and reported. The temporal variability in the β-lactoglobulin content of milk from pasture-fed cows during early lactation and across a production season was investigated. The content of β-lactoglobulin decreased from >10 mg mL⁻¹ in early colostrum to <5 mg mL⁻¹ in mature milk, and the β-lactoglobulin content of skim milk powder trended from 25 to 60 mg g⁻¹ across a season. In view of its allergenicity, these data will improve understanding of the expression of innate β-lactoglobulin in the milk of pasture-grazed dairy herds, thereby providing information that is applicable to the formulation of bovine milk-based products.     

The influence of material properties on the amount of twist of spruce wood during kiln drying

The development of twist in Norway spruce boards (Picea abies Karst.) during normal temperature kiln drying was researched. Tangentially oriented boards were sawn from diametrical radial planks, from which the basic wood properties, i.e. linear shrinkage and grain angle, were determined. The unrestrained boards were kiln dried using a selected drying schedule. During the controlled drying process the moisture content (MC) and twist of the boards were measured. Twist was generally induced by the shrinkage of wood below the fibre saturation point, and increased in proportional to the decrease in MC. The earlier appearance of twist, with regard to MC and drying time, was confirmed in the case of boards sawn from the central part of logs. The final twist amounted to between 10 and 20°/m in the case of boards close to the pith, and decreased to less than 4°/m in the case of boards sawn at a radius of 70 mm from the centre of the logs. Ring curvature had the highest impact on the final twist of the dried boards, followed by grain angle and tangential shrinkage.     

Water retention of wood particles – characterization of polarity and particle size

The basic principle of methods measuring water retention of fibre pulp was adapted for a new method to prove differences in polarity and particle size of wooden particles used for particle board production. With this new method, particles come into contact with the liquid for a short time. Besides the laboratory method, appropriate data analyses of the weight-time curves, including the calculation of a novel polarity coefficient are introduced. The measurement signal was found to be most significantly influenced by the particle properties at the equilibrium of liquid charge and discharge, as well as within the asymptotic levelling phase around 30 s of testing. With increasing particle size, water retention values of both native and thermally modified particles decrease due to reduced specific particle surface. Thermally modified particles show significantly lower water retention values in the range of ?28 to ?46 % and higher variability which is thought to be related to reduced polarity. The method proved to be quick, easy to handle and reproducible.     

The development of wood technology and technology developments in the wood industries—from history to future

The term technology is frequently used in every-day communication and in the specific areas of producing goods and providing services. Technology comprises the science of knowledge and usage of tools and techniques or its systems, methods, organization and material products thereof. The meaning of the word technology itself as well as the specific meaning of the term wood technology has changed over the past centuries of industrialized production systems. The current paper analyses the development of wood technology over a period of about 300 years. Based on various COST Actions and the European Forest-sector Technology Platform current topics of wood technology are addressed and a future outlook is given.     

Development and validation of a tool to recall alcoholic beverage and wine consumption over consumers’ lifetimes

Different past experiences are likely to influence current preferences and consumption through learning processes, such as evaluative conditioning, leading to different flavour preference developments. The ability to measure past experience of alcoholic beverage consumption would be useful in order to understand the drivers of current wine consumption. The developed and validated tool provides reliable data for both past alcohol consumption recall and current wine consumption. Intraclass correlation coefficients (ICC) and F-tests indicated reliability, specifically, high internal consistency (lifetime drinking history and current wine consumption), internal validity and acceptable limits of agreement (current wine consumption relative to a 7-day diary), especially for the most frequently consumed wine (red), demonstrating that the measures taken were reproducible over time. In contrast to previous lifetime alcohol consumption studies, the present study included measures of type of wine consumed. Results justify and encourage the administration of the developed tool on a larger sample, aiming to seek associations between ‘drinking histories’ in order to understand current wine consumption.