In recent years, increased attention has been directed to the development of sustainable, green, and environmentally friendly materials, a field in which cellulose plays an important role. In this study, the susceptibility of solvent exchanged, freeze dried, and spray-dried NFC for a surface modification was examined by employing the acetic anhydride/pyridine system under heterogeneous reaction co nditions. In addition, the influence of the catalyst concentration and the reaction time was studied. The degree of substitution, morphology, degree of crystallinity, hydrophobicity, and thermal stability of acetylated products were examined by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, X-ray powder diffraction analysis, measurements of contact angle, and thermogravimetric analysis.
COBISS.SI-ID: 2454921
The aim of the research was to explain the influence of Al2O3 particles on the solidification characteristics of the matrix within metal matrix composite (MMC). This matrix consisted of AlSi7Mg alloy and elemental Mg (5 mass%). MMCs were prepared by the stir cast method with additions of alumina up to 10 mass%. The solidifications of the said prepared MMCs were monitored using thermal analysis. Their microstructural constituents were analysed using scanning electron microscopy, optic microscopy and X-ray diffraction analysis.
COBISS.SI-ID: 1547615
We report the processing, analysis and testing of magnetocaloric composite materials consisting of La-Fe-Co-Si particles of various size fractions and a polymer matrix. All of the composites have working temperatures close to room temperature. The composites were pressed into thin plates, a geometry favorable for testing the composites in an active magnetic regenerator (AMR). In order to investigate the influence of particle size and binder type (epoxy), eight different epoxy-bonded La-Fe-Co-Si plates were made and analyzed. We found that the higher filling factor that can be achieved by using a mixture of several particle size fractions has beneficial influence on the thermal conductivity. Tests in the AMR revealed that a maximum temperature span of approximately T=10 K under magnetic field change of 0H=1.15 T can be obtained at no cooling load conditions. The stability of the measured T values and the mechanical integrity of sample after cyclic application of a magnetic field have been monitored for 90,000 cycles and showed no significant changes. We therefore conclude that epoxy-bonded La-Fe-Co-Si magnetocaloric composites have good magnetocaloric properties at low material-processing costs and hence represent a competitive way to produce magnetocaloric materials to be used in AMR.
COBISS.SI-ID: 13703963
Kinetic Monte Carlo simulations with model asymmetry in binary Fe-Cu alloy leading to the same microstructure are presented. A method based on thermodynamic data for calculation of interatomic potentials dependent on model asymmetry is presented and evaluated. Results show that kinetic pathways are sensitive to model asymmetry and are compared to the classical growth and coarsening theories. Experimental diffusion data are used and compared to simulation results to determine a realistic combination for simulations.
COBISS.SI-ID: 1519711