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Natural oils from watermelon, cherry, black currant, grape and pomegranate fruit seeds were applied in the synthesis of biopolyols using the transesterification reaction. In this manuscript, the preparation possibility of open-cell foams from a polyurethane system in which petrochemical polyol was fully replaced with biopolyols is analyzed. Firstly, polyurethane foam systems were developed on a laboratory scale, and they were next tested under industrial conditions. It was shown that the foaming method has a significant impact on the foaming process and the cell structure of obtained foams as well as their thermal insulation properties. Based on the conducted research, it was found that the method of processing the polyurethane system has a significant impact on the properties of open-cell spray foams. Foams produced under industrial conditions have a much higher cell density, which has a positive effect on their selected physical–mechanical properties compared to foams produced on a laboratory scale. The open-cell biofoams obtained using a high-pressure machine had apparent densities 12–17 kg/m3, thermal conductivity coefficients 35–37 mW/m·K, closed-cell contents < 10% and were dimensionally stable at low and high temperatures. [ABSTRACT FROM AUTHOR]

Polymer‐based hydrophobic coatings degrade in response to high temperatures or abrasion. Rare‐earth oxides (REOs) as a ceramic material may provide more robust surfaces whose hydrophobicity is maintained due to their specific electron configuration. It has been also shown that REO thin films are stable on the surface of bare materials used in the aerospace industry (i.e., aluminum and titanium alloys). Hence, coating or doping of Al2O3 and TiO2 surfaces with REO might be promising both theoretically and practically. Following our previous studies on cerium‐doped Al2O3 and TiO2, in this work, the density functional theory (DFT) method is applied to investigate the possibility of tuning the wettability of commonly used hydrophilic Al2O3 by surface doping with neodymium (Nd) and europium (Eu). The results indicate that Nd and Eu segregate to the (0001) surface of Al2O3 and thermodynamically stable oxygen termination of dopant is formed. A significant increase in the static water contact angle provide a valuable opportunity for the RE element surface modification of Al2O3, in order to achieve hydrophobicity. [ABSTRACT FROM AUTHOR]

Intrinsically hydrophobic rare-earth oxides (REOs) have emerged as a robust class of ceramics for a variety of applications. Recently, the hydrophobicity of REOs has been observed experimentally and subsequently scrutinized using electronic structure density functional theory (DFT) calculations. In this work, we applied the DFT method to analyze the possibility of tuning the wettability of commonly used hydrophilic Al2O3 and TiO2 by surface doping with Ce. The calculations indicate that Ce can preferentially segregate to the surface of Al2O3 and TiO2 and form a Ce-rich oxide layer, which is stable under a wide range of oxygen chemical potentials. A remarkable increase in the water contact angle is predicted for Ce-doped Al2O3(0001), whereas the water contact angle calculated for Ce-doped TiO2(110) remains unchanged, regardless of the Ce concentration. The wetting properties of Ce-doped Al2O3 are governed by two factors: (1) the unique electronic structure of the rare-earth metal promotes hydrogen bond formation between H2O and surface oxygen; (2) significant relaxation of the surface Ce and O atoms hampers direct interaction between H2O and Al cations, preventing dissociative water adsorption. These results provide a valuable opportunity for Al2O3 surface modification, in terms of achieving hydrophobicity. [ABSTRACT FROM AUTHOR]

Rigid polyurethane foams (RPURF) containing a bio-polyol from rapeseed oil and different phosphorus-based flame retardants were obtained. Triethyl phosphate (TEP), dimethyl propane phosphonate (DMPP) and cyclic phosphonates Addforce CT 901 (20 parts per hundred polyol by weight) were used in the synthesis of RPURF. The influence of used flame retardants on foaming process, cell structure, and physical–mechanical properties as well as flammability of RPURF were examined. The addition of flame retardants influenced the parameters of the cellular structure and decreased compressive strength. All obtained foam materials had a low thermal conductivity coefficient, which allows them to be used as thermal insulation. The research results of bio-based RPURF were compared with foams obtained without bio-polyol. All modified materials had an oxygen index above 21 vol%; therefore, they can be classified as self-extinguishing materials. The analysis of parameters obtained after the cone calorimeter test showed that the modified RPURF have a lower tendency to fire development compared to the reference foams, which was particularly noticeable for the materials with the addition of DMPP. [ABSTRACT FROM AUTHOR]

Intrinsically hydrophobic rare-earth oxides (REOs) have emerged as a robust class of ceramics for a variety of applications. Recently, the hydrophobicity of REOs has been observed experimentally and subsequently scrutinized using electronic structure density functional theory (DFT) calculations. In this work, we applied the DFT method to analyze the possibility of tuning the wettability of commonly used hydrophilic Al 2 O 3 and TiO 2 by surface doping with Ce. The calculations indicate that Ce can preferentially segregate to the surface of Al 2 O 3 and TiO 2 and form a Ce-rich oxide layer, which is stable under a wide range of oxygen chemical potentials. A remarkable increase in the water contact angle is predicted for Ce-doped Al 2 O 3 (0001), whereas the water contact angle calculated for Ce-doped TiO 2 (110) remains unchanged, regardless of the Ce concentration. The wetting properties of Ce-doped Al 2 O 3 are governed by two factors: (1) the unique electronic structure of the rare-earth metal promotes hydrogen bond formation between H 2 O and surface oxygen; (2) significant relaxation of the surface Ce and O atoms hampers direct interaction between H 2 O and Al cations, preventing dissociative water adsorption. These results provide a valuable opportunity for Al 2 O 3 surface modification, in terms of achieving hydrophobicity.