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This paper is an overview of our recent investigations of liquefied wood (LW) for preparation and application of wood adhesives and wood surface finishes. For the purpose of wood bonding, poplar wood (Populus nigra L.) was liquefied with ethylene glycol (EG) and sulphuric acid. The process of the curing of LW at different conditions was characterized using differential scanning calorimetry (DSC). The effect of the press temperature and the pressing time on the shear strength of bonds was monitored after the bonding of 5mm thick beech (Fagus sylvatica L.) lamellas. According to the results of DSC measurements, the curing process of the LW took place in two phases. In the initial physical phase the removal of water and EG from the LW occurred. This phase was followed by an exothermic chemical reaction. It was found that the optimum conditions for bonding beech lamellas were: a ratio between poplar and EG of 1:1, a press temperature of 180°C, and a pressing time of 12 minutes. Using such conditions it was possible to obtain bonds with a dry shear strength of about 7N/mm². For preparation of polyurethane wood coatings, poplar wood was liquefied with diethylene glycol (DEG) and the excessive DEG was removed from the reaction mixture prior to curing with isocyanate type hardener. For the purpose of preparation of light-coloured polyurethane coatings from bleached liquefied wood, liquefaction of wood was conducted with a mixture of polyethylene glycol (PEG) and glycerol (GLY) at a 9:1 ratio. Both LW based PU coatings and bleached LW based PU finishes were in the most relevant properties comparable to commercial polyurethane wood coatings. [ABSTRACT FROM AUTHOR]

Thermal modification is the most important commercial modification procedure. Thermally modified (TM) wood has improved durability, but its performance does not meet expectations predominately under moist conditions. To reduce water uptake of TM wood, Norway spruce specimens were treated with suspensions of a natural wax by dipping impregnation (DipI) or by vacuum-pressure impregnation (VPI). Wax-treated specimens were subsequently TM at 185, 200, 215, and 230°C. Control specimens were heated up to 100°C only. Contact angle (CA), short-term and long-term water uptake, bending strength, and performance against wood decay fungi of the resulting material were determined. The results show that a combination of wax treatment and thermal modification have a synergistic effect that considerably improves hydrophobicity, reduces liquid water uptake, slows down water vapor uptake, and improves the resistance against fungal decay of the treated material. [ABSTRACT FROM AUTHOR]

In this study, we modified melamine-formaldehyde (MF) resin adhesive with liquefied wood (LW) and determined the properties of MF–LW adhesive mixtures. Furthermore, we produced particleboards using prepared MF–LW mixtures and evaluated their mechanical and physical properties. Results showed that with increasing content of LW in the adhesive mixture gel time and peak temperature increased while reaction enthalpy decreased. With increasing substitution of MF resin adhesive with LW the thermal stability of adhesive mixture reduced, namely thermal degradation started at lower temperature and weight loss increased. Properties of particleboards improved with increasing amount of LW in the adhesive mixture up to 20% and then deteriorated. Nevertheless, the properties of particleboard with 30% LW in the adhesive mixture were comparable to the properties of particleboard without LW while they worsen at greater portion of LW. Consequently, MF resin adhesive with 30% LW substitution could be used to produce particleboards with suitable mechanical properties and reduced formaldehyde release content. [ABSTRACT FROM PUBLISHER]

The number of commercial products claiming self-cleaning properties is rising and testing of long-term activity and durability of such coatings needs to be addressed more. The time-dependent changes of different characteristics like haze, transparency, and color are essential for transparent glazing materials. Herein, we aimed to examine whether the laboratory results obtained on the Zr-modified-titania-silica (TiZr) self-cleaning materials would translate to larger-scale outdoor-exposed testing. TiZr thin films were deposited via spraying onto float glass window surfaces and exposed into three different environments for 20 months. For comparison, a commercially available active SGG BIOCLEANTM glass and standard float glass were simultaneously exposed in the same conditions. It was shown that the self-cleaning property of either a commercial product or TiZr-coated float glass was not considerably effective in real field test conditions, although the previous laboratory tests showed pronounced photocatalytic activity of TiZr thin films. The inclination angle; however, was shown to have a considerable effect on the self-cleaning ability of samples, as did the rain patterns during the testing period. On the other hand, the anti-fogging effect of our TiZr material was very well expressed in controlled laboratory conditions (measuring droplet formation time) as well as in the real outdoor environment. [ABSTRACT FROM AUTHOR]