Deposition of TiO 2 nanoparticles on wood surface was realised to improve the wood stability against ultraviolet (UV) light and moisture degradation. Photocatalytic activity of TiO 2 nanoparticles was utilised for protection of the wood surface. TiO 2 nano-particles were achieved by a sol-gel deposition method using EtOH/TiCl4 solution. Dip-coating process and subsequent annealing were used to realise nano-particles on wood surface. This method of deposition was utilised for the conformal covering of the wood structure as demonstrated by morphological investigation of the prepared samples by field emission scanning electron microscopy. Colour change measurements and Fourier transform infrared spectroscopy were used to analyse the lignin and carbonyl degradation of uncoated and coated wood during the UV exposure. Moisture protection of the coated wood was investigated by measuring the contact angle of the distilled water and wood surface. The measurements showed the UV and moisture protection of the TiO 2 layer.

Heat treatment of wood is an effective method by which to improve the dimensional stability and biological durability, but the mechanical strength is decreased at the same time. Besides chemical modification of cell-wall constituents, physical weakening of the microstructure owing to heat-induced defects may also contribute to strength loss. Therefore, anatomical properties of heat-treated beech (Fagus sylvatica L.) and spruce (Picea abies Karst.), studied by light microscopic and scanning electron microscopic analysis, and their interrelation with strength properties and structural integrity were investigated. For determination of structural integrity, the high-energyÁmultiple-impact (HEMI) test was applied. Microscopic analyses showed frequent formation of radial cracks in heat-treated beech close to the rays as well as tangential cracks in the latewood of spruce. In addition, the modulus of rupture was more affected by the heat treatments than the resistance to impact milling (RIM) determined by the HEMI test, because RIM is based on multiple fractures on the microlevel that are not affected by the formation of intercellular cracks or other defects due to the heat treatment. It was concluded that heat-induced defects in the wood microstructure contribute to the substantial strength loss of thermally modified timber.

In order to quantify the effect of temperature on the mechanical properties of hemp fiber polypropylene composites, formulations containing 25% and 40% (by weight) hemp fiber were produced and tested at three representative temperatures of 256, 296, and 336 K. Flexural, tensile, and impact tests, as well as dynamic mechanical analysis, were performed and the reduction in mechanical properties were evaluated. Impact resistance was independent of temperature, whereas flexural and tensile properties were strongly affected. The highest reductions were observed in stiffness (modulus) values and flexural properties were reduced to a higher degree. The reductions in mechanical properties were well explained by a simple quadratic curve-fitting procedure applied to experimental data. Dynamic mechanical analysis revealed no change in glass transition temperature when the fiber content was increased but the composite material had better temperature resistance at higher fiber content. The results of the present study will be helpful in determining the end-use application of these composite materials.

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