Microspheres as potential fillers in composite polymeric materials

Microspheres used in our work were acquired from one of Kazakhstan coal-fueled power plant. The size of the microspheres varied between 45 and 400 μm, the median particle size (D50) was 158 μm. Microscopic analysis revealed that the material consisted mainly of cenospheres. The results of elemental and oxide analysis showed that microspheres were composed of aluminosilicates. Identified crystalline phases were mullite (approx. 12 %) and trace amount of quartz (silica). Microscopic observations of the cross-sectional surface of both unmodified PUR foam and foams modified with microspheres showed a well formed, cellular structure of all materials. The observed cells are polyhedron in shape, most of them are closed, microspheres were uniformly distributed within polymer matrix and placed between cells. The apparent densities calculations of the samples showed that when microspheres were added to the polymer matrix, apparent density of the resulting composite materials increased. The results of elemental analysis pointed out the highest content of all three elements in unmodified PUR foam sample. The addition of the microspheres to the system resulted in decrease of the concentration of all three elements

Macromonomers as a Novel Way to Investigate and Tailor Silicon-Oxycarbide-Based Materials Obtained from Polymeric Preceramic Precursors

It has been shown that bifunctional monomers (D units), which are used to increase the carbon content in silicon oxycarbide precursors, can form volatile oligomers, thus affecting the amount of carbon available during the transition into the final material in the annealing process. Additionally, an uneven distribution of carbon-rich mers may lead to the formation of a free-carbon phase, instead of the incorporation of carbon atoms into the silicon matrix. In this study, a novel two-step approach was utilized. Firstly, a macromonomer containing a number of structural units with precise structure was synthesized, which was later polycondensed into a ceramic precursor. Chlorodimethylsilane modified 2,4,6,8-tetramethylcyclotetrasiloxane was used as a silicon oxycarbide precursor monomer containing both T and D structural units (i.e., silicon atoms bonded to three and two oxygen atoms, respectively), with well-defined interconnections between structural units. Such a macromonomer prevents the formation of small siloxane rings, and has a very limited number of possible combinations of structural units neighboring each silicon atom. This, after investigation using IR, XRD, TG and elemental analysis, gave insight into the effect of “anchoring” silicon atoms bonded to two methyl groups, as well as the impact of their distribution in comparison to the materials obtained using simple monomers containing a single silicon atom (structural unit)

Trace Elements and Mineralogy of Upper Permian (Zechstein) Potash Deposits in Poland

Mineral composition and content analysis of selected trace elements (Ag, As, Ba, Be, Br, Cd, Ce, Co, Cr, Cs, Cu, Ga, I, La, Li, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sn, Sr, Ti, Tl, U, V, and Zn; 308 rock samples) were studied in the Upper Permian (Zechstein) potash-bearing deposits in Poland. They represented K–Mg chlorides of PZ2 and PZ3 cyclothems from four salt domes and stratiform K–Mg sulphates of PZ1 cyclothem. The dominant mineral components of K–Mg sulphates (polyhalite) are anhydrite and polyhalite. The most common minerals of the K–Mg salts of PZ2 cyclothem are halite, sylvite, kieserite, and anhydrite, and the most common of PZ3 cyclothem are halite, carnallite, kieserite, and anhydrite. Most analysed trace elements in the Zechstein potash-bearing deposits show a low content (up to 26 mg/kg) that eliminates them as potential profitable source rocks of such required elements as Ce, Cs, La, Li, or Rb. Common elements, such as Br, Fe, and Sr, are more easily exploited from natural brines, sulphate, and ore deposits

Trace Elements and Mineralogy of Upper Permian (Zechstein) Potash Deposits in Poland

Mineral composition and content analysis of selected trace elements (Ag, As, Ba, Be, Br, Cd, Ce, Co, Cr, Cs, Cu, Ga, I, La, Li, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sn, Sr, Ti, Tl, U, V, and Zn; 308 rock samples) were studied in the Upper Permian (Zechstein) potash-bearing deposits in Poland. They represented K–Mg chlorides of PZ2 and PZ3 cyclothems from four salt domes and stratiform K–Mg sulphates of PZ1 cyclothem. The dominant mineral components of K–Mg sulphates (polyhalite) are anhydrite and polyhalite. The most common minerals of the K–Mg salts of PZ2 cyclothem are halite, sylvite, kieserite, and anhydrite, and the most common of PZ3 cyclothem are halite, carnallite, kieserite, and anhydrite. Most analysed trace elements in the Zechstein potash-bearing deposits show a low content (up to 26 mg/kg) that eliminates them as potential profitable source rocks of such required elements as Ce, Cs, La, Li, or Rb. Common elements, such as Br, Fe, and Sr, are more easily exploited from natural brines, sulphate, and ore deposits

Thermal Behavior of Clinoptilolite

Understanding the thermal properties of zeolites is crucial for their industrial applications. This study explores the thermal stability and dehydration process of clinoptilolite using high-temperature X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Clinoptilolite’s thermal decomposition was monitored from 25 °C to 1200 °C, with results analyzed based on its crystal structure. Principal components analysis (PCA) of the DRIFT spectra indicated progressive water removal and dehydration upon heating, leading to the formation of hydrogen bonds. Thermogravimetric analysis (TGA) revealed a two-step endothermic weight loss: initially, physically adsorbed water was lost up to 100 °C, followed by the removal of tightly bound water and hydroxyl groups until 800 °C. Clinoptilolite remained the dominant phase up to 800 °C, after which albite and cristobalite took over. Rietveld refinement showed that the sample initially contained 70% clinoptilolite, 24% albite, and 6% cristobalite. Above 800 °C, clinoptilolite disappeared, leaving 93% albite and 7% cristobalite. FT-IR spectra changes due to water loss were evident: drying of adsorbed water occurred up to 75 °C and minimal changes were observed from 75 °C to 135 °C, followed by further dehydration until 240 °C. Complete dehydration was confirmed by the disappearance of OH stretching vibration bands by 395 °C, consistent with TGA findings

Kinetic study of the pyrolysis and gasification of Rosa multiflora and Miscanthus giganteus biomasses via thermogravimetric analysis

The thermal behaviour of the Rosa multiflora (3 groups: control, irradiated 3 × 3 seconds, and 3 × 9 seconds by low power laser of wavelength 672 nm) and Miscanthus giganteus (3 groups: R, V, and Z) biomass by thermogravimetric analysis (TGA) was studied at heating rate 3 K per minute from ambient temperature to 950°C. The TGA tests were performed in high purity CO2 (99.998%) with a flow rate 200 mL per minute and 100 mg of sample, milled and sieved to a particle size below 250 μm. In contrast to the majority of the conducted examinations, which are carried out with the use of chars, the measurements were conducted for raw biomass. The kinetics parameters of the biomass conversion process were determined from the experimental data by integral methods (Murray and White; Senum and Yang). The methods used have allowed distinguishing and analysing the different stages of the process, i. e. the primary and secondary pyrolysis as well as gasification. Both methods gave comparable results. The activation energy determined using more accurate Senum and Yang method ranged from 85-88 kJ/mol (primary pyrolysis), from 29-32 kJ/mol (secondary pyrolysis), and from 173-190 kJ/mol (gasification) for Rosa multiflora biomass and from 86-111 kJ/mol (primary pyrolysis), from 22-25 kJ/mol (secondary pyrolysis), and from 181-217 kJ/mol (gasification) for Miscanthus giganteus. The pre-exponential factor was in the range of 5.95 ⋅ 106 to 13.05 ⋅ 106 min–1 (primary pyrolysis), 2.25-4.22 min–1 (secondary pyrolysis), and 13.96 ⋅ 106 to 1.18 ⋅ 108 min–1 (gasification) for Rosa multiflora biomass and 6.94 ⋅ 106 to 1.79 ⋅ 109 min–1 (primary pyrolysis), 0.88-1.62 min–1 (secondary pyrolysis), and 131.54 ⋅ 106 to 1.92 ⋅ 109 min-1 (gasification) for Miscanthus giganteus biomass