Rigid polyurethane (PUR) foams are widely used as heat insulation material in construction industry or for electronic appliances manufacturing. After finishing their lifetime it is necessary to eliminate foam wastes. The aim of this study was to prepare a pair of industrial polyurethane adhesives of medium viscosity containing recycled rigid polyurethane foam. Three methods of milling were tested: knife-milling, two-roll milling and ball-milling. Only two-roll milling gives the PUR micro-powder usable for following adhesives modification. The micro-powder was used as passive filler in polyurethane adhesives and potential reactivity for polyol pack replacement was studied. Hydroxyl and amine numbers were determined in mixture with virgin polyol. One-component polyurethane prepolymer adhesive was prepared using various dosages of the micro powder and the tensile strength of bound wood was measured. As additional parameters also free film adhesive mechanical parameters were tested and particle size distribution of the micro powder was analysed. Two adhesive formulations were prepared for independent evaluation of the micro

The aim of this paper was to analyze selected properties of beech wood (Fagus sylvatica L.) treated by one-sided surface charring. Specimens were one-side charred with a hot plate using several time-temperature combinations (from 200 to 400 °C). Characteristics such as colour, discoloration, surface roughness, fire resistance, total carbohydrate content at several wood layers and decay resistance were evaluated. Surface charring was applied to the radial and tangential surfaces. Colour measurements showed that the surface of the wood turned grey due to charring. In addition to colour measurements, other experiments showed significant differences between radial and tangential specimens due to their different structures. The higher the temperature used in treating them, the lower the roughness values for radial specimens, while the trend for tangential specimens was the opposite. A smoother surface is more fire resistant, so radial specimens are generally better in this regard. Tangential specimens are more susceptible during preparation to forming cracks that impair flame resistance because a continuous protective densified layer is not formed. The determination of total carbohydrates revealed significant changes at various wood depths after surface charring. These changes were more predictable in radial specimens due to the annual ring orientation, because each layer consisted of a similar earlywood/latewood ratio. Finally, when decay resistance was assessed, weight loss was found to be lower in all specimens than in the references. The results suggest that charring at a particular combination of temperature and time improved the investigated properties of the surface-modified beech.

Three synthetized polymorphs of calcium carbonate have been tested in combination with the suspension of nanolime particles as potential consolidating agents for contrasting stone decay and overcome some of the limitations of nanolime agents when applied to substrates with large porosity. The modifications induced in the pore network of the Maastricht limestone were analyzed with microscopy and in a non-invasive fashion with small angle neutron scattering and synchrotron radiation micro-computed tomography. A reduction in porosity and pore accessibility at the micrometric scale was detected with the latter technique, and ascribed to the improved pore-filling capacity of the consolidation agent containing CaCO3 particles. These were found to be effectively bound to the carbonated nanolime, strengthening the pore-matrix microstructure. Penetration depth and positive effect on porosity were found to depend on the particle size and shape. Absence of significant changes in the fractal nature of the pore surface at the nanoscale, was interpreted as indication of the negligible contribution of nanolime-based materials in the consolidation of stones with large porosity. However, the results indicate that in such cases, their effectiveness may be enhanced when used in combination with CaCO3 particles, owing to the synergic effect of chemical/structural compatibility and particle size distribution.

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Effect of the shape of 3D printed samples on fire behavior of polyethylene terephthalate glycol (PET‐G) and PET‐G additivated with a mix of aluminum hypophosphite (AHP) and melamine cyanurate as flame retardant, was investigated. The additives improved fire performance (e.g., maximum average rate of heat emission, total oxygen consumption, heat release rate indices) irrespective of structural complexity, favoring carbonaceous char formation. However, at increasing structural complexity, they promoted higher release of smoke, compared to neat PET‐G, because of a change in the prevalent retardation mechanism, which became dominated by the flame inhibition action of AHP. Consequently, the synergistic effect obtained combining the two additives, was hindered. Impact of product design on mechanisms of fire retardation helps in devising engineering solutions aimed at meeting required level of fire‐safety performance, which should be tailored to the specific product.