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Spray polyurethane foam (SPF) roofs are widely used in North America. Much fewer usage examples and experience can be found in Northern European cold climatic conditions. This study analyses hygrothermal performance and the reasons for the roof’s degradation and end of service life of an SPF and polyurea roof. The service life of the roof is over and major reconstruction is needed eight year after construction. The current study uses field measurements included onsite temperature and humidity measurements and extensive surveying, the roof was opened from several locations and test samples were taken for laboratory tests. The influence of UV radiation on the loss of adhesion was tested. Solar radiation quickly degraded the top surface of the in-situ sprayed polyurethane foam insulation causing a weak connection between the foam layers. Due to mechanically damaged and UV degraded polyurea roofing, water has leaked into the SPF. The water inside or below the foam evaporated during sunny days and broke the adhesion of different foam layers. Larger foam blisters were observed on the upper part of the insulation caused by high water vapour pressure. This is considered the most realistic cause of separation of the SPF layers. The analyse of hygrothermal performance, service life, and durability prediction should be included into the design process, especially for structures with small or without long term performance experience.

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In the present study different methods for the determination of aspen lignin were investigated. In experiments, dried samples of extractive-free aspen wood and grinded bleached-chemo-thermo-mechanical-pulp (BCTMP) of aspen were used. For isolating lignin from aspen wood and BCTMP, Klason method was used. For the quantification of lignin content, a series of aspen wood powder/microcrystalline cellulose binder were mixed and analysed with FTIR-ATR and UV-VIS. To compare with colour reactions, an average content 21% of lignin was assigned to experimental content in 100% aspen wood powder. FTIR-ATR absorbance maximum between 1234-1237 cm-1 and UV-VIS pseudo-absorbance of measured samples maximum at 280 nm were taken as measurement points for the calibration of lignin content. Nearly linear dependence was established with both methods. Weisner and Mäule colour tests were used for staining to detect lignin in samples. Suspensions, containing samples with staining solution, were prepared and photographed. Best positive Weisner reaction with violet colour, both with aspen wood and BCTMP samples, were established with the 1:1 phloroglucinol/HCl staining solution. Carefully mixed suspension of 0.1 g samples and 5 min reaction time were applied. In Mäule reaction, intensive red colour appeared to samples after 10 min treatment with 1% KMnO4. Samples were washed with distilled water and treated with 3% aqueous HCl until the colour changed from black to beige/yellow. Then samples were treated with concentrated NH3⋅H2O for 2 min to achieve the most intensive colour. A simple semiquantitative method for detection of lignin in BCTMP was worked out. [ABSTRACT FROM AUTHOR]

The aim of this research was to determine the mechanical properties of pinewood, swollen in water and aqueous solutions of ethanol and acetone. For this purpose, pine sapwood specimens were swollen in water, ethanol, acetone and aqueous solutions of ethanol and acetone. Static bending and compression strength along the grain and deflection in bending were determined. The results of this study show that a strong correlation exists between the strength properties and the swelling degree of pine sapwood. Pure substances and aqueous solutions influenced the mechanical properties of wood in different ways. Pine sapwood, swollen in aqueous solutions of ethanol, has better elastic properties compared to wood, swollen in other organic liquids used in this study. [ABSTRACT FROM AUTHOR]