STUDY OF PHYSICO-CHEMICAL PROPERTIES OF NANOCOMPOSITE MADE FROM MIXTURE OF NATURAL POLYAMIDE BASE AND FeO FILLER

Xanthan is an important polysaccharide widely used in many industrial fields. It is produced by the bacteria Xanthomonascampestris. Chemical modification of xanthan can open up new horizons for its use. In this work, xanthan butyl ester was obtained for the first time by the interaction of xanthan and bromobutane using sodium hydroxide as a catalyst. The composition and structure of the obtained new xanthan derivative was studied by elemental analysis, IR spectroscopy, X-ray phase analysis, scanning electron microscopy and thermal analysis. The introduction of a butyl group into the xanthan molecule was proved by elemental analysis and IR spectroscopy by the appearance of corresponding bands. It was shown by X-ray phase analysis that xanthan butyl ether has a more X-ray amorphous structure in comparison with the original xanthan. It was shown by scanning electron microscopy that xanthan butyl ether powder consists of particles of a larger size and a layered structure in comparison with the original xanthan. It has been shown by thermal analysis that xanthan butyl ether is less thermostable than the starting xanthan

Room-temperature ionic liquids (RTILs), i.e. organic molten salts with melting points below 100 ◦C, have been intensively developed for electrolytic media in various electrochemical systems due to the fact that RTILs have unique physicochemical properties such as favorable solubility of organic and inorganic compounds, relatively high ionic conductivity, no measurable vapor pressure, high thermal stability, low flammability, etc. Another advantage of RTILs is a purposive selection of the ion species and their designability. Although typical anion species employed for RTILs include sulfonylamide-based anions, e.g. bis(trifluoromethylsulfonyl)amide (N(SO2CF3)2 -, TFSA) and bis(fluorosulfonyl)amide (N(SO2F)2 -, FSA) anions, asymmetric fluorosulfonyl(trifluoromethylsulfonyl)amide (N(SO2F)(SO2CF3)-, FTA) anion have attracted attention in recent years. In our preliminary approach, FTA anion based RTILs in combination with quaternary phosphonium cationswe previously reported,1,2 examining their transport property behavior. In this work, we report design and synthesis of several FTA-based phosphonium RTILs (Fig. 1) as potential electrolytes available for electrochemical systems, summarizing their physicochemical and thermal characteristics including the thermal decomposition as well as the transport property behaviors.The preparation and purification of the phosphonium RTILs were carried out according to the procedures described in our previously published papers.1-3 The phosphonium RTILs were prepared by aqueous ion exchange reactions of the precursor phosphonium bromides with lithium FTA. The resulting crude RTILs was extracted by dichloromethane, and then purified by washing with pure water several times until no residual bromide anion was detected with the use of AgNO3. The RTILs was dried under high vacuum for at least 1 day at 80 ◦C prior to use. The physicochemical and electrochemical properties such as conductivity (ac impedance method, using a two-Pt electrode cell), viscosity (cone-plate type viscometer), density, melting point (DSC), thermal decomposition temperature (TGA) were measured under dry argon atmosphere.Several phosphonium RTILs melting at ambient temperatures were successfully prepared by combination with the FTA anion. Table 1 lists the physicochemical properties and thermal decomposition temperatures (10% weight loss) of the FTA-based phosphonium RTILs. All FTA-based phosphonium RTILs showed typical temperature-dependent behaviors for density, viscosity and electrical conductivity. It should be noted that P222(1O1)-FTA exhibited the lowest viscosity and the highest conductivity in the FTA-based phosphonium RTILs, which is attributed to the introducing effect of ether oxygen atom into the cation on the flexibility of the alkyl chain. On the other hand, the thermal decomposition temperatures of the FTA-based phosphonium RTILs tended to be relatively low (less than 300 ◦C) compared to those of TFSA-based RTILs. The detailed thermal decomposition behavior observed in the thermogravimetric traces will be discussed in comparison with both corresponding TFSA- and FSA-based RTILs.References1) K. Tsunashima, et al, Electrochem. Commun., 9, 2353 (2007).2) K. Tsunashima, et al, Electrochemistry, 75, 734 (2007).3) K. Tsunashima, et al, Electrochem. Commun., 13, 178 (2011). Figure 1

In this study, complexes of manganese (II) and zinc(II) with ligands (salicylic acid and cysteine) [MnL2(H2O)2]2H2O, [ZnL2(H2O)2]2H2O have been synthesized. It is shown that the composition of the obtained complexes depends on the ratio of the initial components. The composition and structure of the complexes have been studied by elemental, X-ray phase analysis, (DLS)method, UV-VIS spectroscopy, IR spectral and thermogravimetric analysis. The method of UV spectroscopy has show that the ligands in the composition of the metal (II) complexes enter the neutral form and coordinate with the complexing agent through the nitrogen atom. According to UV spectroscopy has d-d transition was observed in the complexes corresponding to the wavelength for Mn (II) 480-560 nm, for Zn (II) complex 238 nm. The results of thermogravimetric studies have shown that the final product of the thermal decomposition of all compounds is metal oxide, respectively. The complex compounds of manganese and zinc with the amino acids cysteine, methionine, glycine and salicylic acid and nanoparticles of Fe2 O3 have a positive effect on seed germination, the synthesis of photosynthetic pigments and activity of ascorbate peroxidase in wheat leaves

At a fire scene caused by spontaneous combustion of drying oils and semi-drying oils, long heat storage is thought to produce thermal degraded oils in the vicinity of the fire occurrence point. In other words, even if the cause of a fire scene is difficult to judge from the appearance of the damaged scene where spontaneous combustion occurred, the possibility of spontaneous combustion might be considered more clearly by proving the existence of thermal degraded parts in oily debris. Results derived from both appearance and evidence are forensically reliable. It is considered that not only are changes of fatty acid composition observed in thermal degraded parts, but also changes of physical and thermodynamic properties. This paper focuses on thermal analyses as the method to distinguish these changes. The purpose of this paper is also to discuss the validity of thermal analyses as the method to prove the existence of thermal degraded parts in oily debris. Differential scanning calorimetry and thermogravimetry were applied to thermal degraded samples produced in experiments, and so the freezing point and thermal decomposition temperature were measured. Furthermore, a kinetic study was carried out based on the isoconversion method; using the value of activation energy derived from the line gradients, master curves were drawn. In the course of considering the freezing point, thermal decomposition temperature, the parallel relation among the lines and convergent state of master curve, and the distinguishable possibility of thermal degraded samples were discussed. In conclusion, this paper clarified that a kinetic study based on the isoconversion method allowed us to distinguish parts of a slight thermal degradation. This method is effective in proving thermal degraded parts existing in oily debris.

Quantum chemical aided prediction of the thermal decomposition mechanisms and temperatures of ionic liquids

The miscibility of chitosan/poly(ethylene oxide) (CS/PEO) blends was investigated by a combination of experiment and molecular simulation. Results from X-ray diffraction (WAXD) and thermal analysis (DSC) suggest that the maximum miscibility was seen at the PEO weight fraction (w PEO) =0.2; the optimum stoichiometric ratio for CS and PEO functional groups. The change in vibrational frequencies from infrared spectra was attributed to the specific interaction between PEO ether oxygen with the amino and hydroxyl groups of CS. Radial distribution functions (RDF) from MD simulation suggest that all CS functional groups (NH2, C3-OH, and C6-OH) can interact with PEO ether groups for which NH2 has the highest activity. For CS hydroxyl groups, a more significant contribution of C6-OH rather than C3-OH groups that interact with PEO ether oxygen was observed. The interaction parameter (χ) determined from MD simulation was in good agreement with that of the DSC experiment (χCS-PEO = -0.21). Based on a comparison between χ and χ critical , CS/PEO blend was predicted to be miscible for w PEO <0.58 with a maximum at w PEO =0.2. In addition, the order parameter from the mesoscale simulation was employed to monitor the phase separation in these blends. From MesoDyn simulation, the miscibility was decreased with increasing PEO content, and miscible CS/PEO blends were obtained only with w PEO <0.58, in good agreement with MD simulation and experiment.

The article discusses the principal methods for obtaining carbon composite nanomaterials and highlights the thermolysis method as one of them. In order to understand the essence of thermal decomposition processes as a method for synthesis of carbon nanomaterials, aromatic iron(III) carboxylates have been considered. These are iron(III) 8-hydroxyquinolinate, benzoate, salicylate, phthalate, and p-aminobenzoate. The article discusses the procedure for the synthesis of these iron(III) carboxylates under standard conditions in detail. The thermal decomposition process was carried out in two media (air as oxidizing one and argon as neutral one) to compare the obtained products. For a detailed study of the processes of decomposition of iron(III) carboxylates, the thermal analysis methods (TG and DSC) were used on a Netzsch 449 Jupiter synchronous thermal analyzer. In order to study the morphology and composition of the products, X-ray phase analysis, optical and scanning electron microscopy, as well as X-ray fluorescence microanalysis were used. We used a Rigaku Ultima IV X-ray diffractometer and a scanning electron microscope with a Jeol JSM-7001F elemental microanalysis attachment. Based on the obtained results, the expected formulas of the initial iron(III) carboxylates were calculated. The mechanisms of the processes occurring during the thermal decomposition of iron(III) aromatic carboxylates were also proposed. For a more accurate determination of the composition of the synthesized iron(III) carboxylates and a more appropriate description of the processes of thermal decomposition of these salts, the corresponding aromatic carboxylic acids were also subjected to thermal decomposition. The appendix to the article contains the data for a more accurate interpretation of the results and a more detailed description of the thermal decomposition processes.

The subject of this work is oxide potassium-titanium bronzes.&#x0D; The purpose of the work: to establish the relationship between the dispersion of samples of oxide potassium-titanium bronze and its physicochemical properties.&#x0D; Synthesis methods: self-propagating high-temperature synthesis (SHS), mechanosynthesis. Research methods used in the work: X-ray phase analysis (XRF), optical method for determining particle size, four-probe method for determining electrical conductivity, thermal analysis, method for determining chemical resistance.&#x0D; Results of the study: particle sizes were determined, which are 400, 200 and 40 nm. The work is devoted to the study of the influence of fineness on the structure and physicochemical properties of compounds of variable composition on the example of titanium oxide bronzes. A nanocrystalline sample of oxide potassium-titanium bronze was obtained by mechanosynthesis, coarse powders were obtained by SHS. The obtained samples were identified by X-ray phase analysis. The optical method of analysis determined the particle sizes, which are 400, 200 and 40 nm. It has been established that nanocrystalline samples of oxide potassium-titanium bronze are less resistant to aggressive media. Reducing the particle size does not affect the thermal stability. In the transition to nanoscale, the specific electrical conductivity increases by 1.5 times and amounts to 0,076 Ohm-1cm-1. The volume density of defects in the nanocrystalline structure of oxide potassium-titanium bronze is calculated, which is 1013 cm-2.

Hydrogen-Bonding-Induced H-Aggregation of Charge-Transfer Complexes for Ultra-Efficient Second Near-Infrared Region Photothermal Conversion

Single crystals of organic optic material 4–Ethoxy Benzaldehyde–4'–N'–Methyl Stilbazolium Hexafluorophosphate (EMBSHP) were grown by slow evaporation technique at room temperature using acetone – water (3:1) mixed solvent. The grown crystal was subjected to single crystal X – ray diffraction analysis to identify the crystal structure and lattice parameter. The crystal belongs to the triclinic crystal system. The composition of the crystal was studied by CHN analysis. The presence of functional groups of the title crystal were confirmed from the FTIR spectral studies. The optical transmission range of the grown crystal was measured by UV – Vis – NIR spectral studies. The melting point of the grown crystal was found from DSC analysis. Introduction. Organic NLO materials with excellent optical characteristics such as high sensitivity and short response time have attracted much attention due to their potential applications in optical switching, optical processing, optical computing, optical data storage and terahertz (THZ) technology. Among the numerous organic materials, the well-known and most investigated organic NLO crystal is the stilbazolium salt trans-4-N-(dimethylamino)-N-Methyl-4-stilbazolium tosylate (DAST). It has very high electro optical (EO) and NLO figures of merit. Among all the other organic THz material, DAST has the largest NLO coefficient, d11 of 540 ± 110 pm/V at ~1540 nm, EO figure of merit r11=47 ± 8 pm/V at ~1535 nm and lower dielectric constant making it suitable for optoelectronic applications [1,2]. The advancement in the field of photonics have increased the demand for new nonlinear optical (NLO) materials. Especially, molecules exhibiting strong two photon absorption (TPA) are of practical importance in photons applications such as frequency up conversion lasing, three dimensional fluorescence imaging and multi photon microscopy ,eye and sensor protection, optical signal reshaping and stabilizing fast fluctuations of laser power. To expand these utilizing, designing the molecule with large TPA cross section plays a vital role [3]. DAST crystal can generate short THz pulse by optical rectification with a sub-picosecond laser [4, 5], or widely tunable THz waves by different frequency generation (DFG) with a dual wavelength nanosecond laser [6]. In this present study, the tosylate anion of DAST is replaced by Hexafluorophosphate (PF-6) and two methyl group along with nitrogen in the cation is replaced by ethoxy group for achieving the stilbazolium crystal 4-Ethoxy benzaldehyde 4'-N'-methyl stilbazolium Hexafluorophosphate (EMBSHP). The grown crystal has been subjected to single crystal XRD, CHN, FTIR, Optical absorption and thermal analysis.

Linear and branched zinc(II) xanthates with varying alkyl chain length were synthesized and characterized by 1H NMR, 13C NMR, and IR spectroscopy, as well as elemental analysis. Zinc sulfide as the final decomposition product upon thermal annealing of zinc(II) xanthates was confirmed by XRD analysis. Cure time for epoxy resin composite at various temperatures was analyzed employing zinc(II) xanthates (5 % mass) as latent cure catalysts. XRD investigation of the cured epoxy resin including zinc(II) xanthates upon thermal annealing revealed the presence of ZnS in‐situ in the composite matrix, indicating the in‐situ thermal decomposition of zinc(II) xanthates as probable mechanism for curing. Thermogravimetric analysis was performed to investigate the thermal decomposition temperature trend of zinc(II) xanthates. A parallel trend was observed correlating the thermal decomposition temperature trend of zinc(II) xanthates and the order of curing catalytic efficiency utilizing zinc(II) xanthates. In the case of linear alkylzinc(II) xanthates with an increase in the alkyl chain length, both thermal decomposition temperature and the cure time were enhanced. In contrast, in case of branched alkyl chain zinc(II) xanthates with increasing alkyl chain length show decreasing thermal decomposition temperature as well as cure time.

Phytic acid is a natural compound widely used as depigmenting agent in galenic cosmetic emulsions. However, we have observed experimentally that phytic acid, when heated to 150 ºC for around one hour, shows evidence of thermal decomposition. Few studies investigating this substance alone with regard to its stability are available in the literature. This fact prompted the present study to characterize this species and its thermal behavior using thermal analysis (TG/DTG and DSC) and to associate the results of these techniques with those obtained by elemental analysis (EA) and absorption spectroscopy in the infrared region. The TG/DTG and DSC curves allowed evaluation of the thermal behavior of the sample of phytic acid and enabled use of the non-isothermal thermogravimetric method to study the kinetics of the three main mass-loss events: dehydration I, dehydration II and thermal decomposition. The combination of infrared absorption spectroscopy and elemental analysis techniques allowed evaluation of the intermediate products of the thermal decomposition of phytic acid. The infrared spectra of samples taken during the heating process revealed a reduction in the intensity of the absorption band related to O-H stretching as a result of the dehydration process. Furthermore, elemental analysis results showed an increase in the carbon content and a decrease in the hydrogen content at temperatures of 95, 150, 263 and 380 °C. Visually, darkening of the material was observed at 150 °C, indicating that the thermal decomposition of the material started at this temperature. At a temperature of 380 °C, thermal decomposition progressed, leading to a decrease in carbon and hydrogen. The results of thermogravimetry coupled with those of elemental analysis allow us to conclude that there was agreement between the percentages of phytic acid found in aqueous solution. The kinetic study by the non-isothermal thermogravimetric method showed that the dehydration process occurred in two stages. Dehydration step I promoted a process of vaporization of water (reaction order of zero), whereas dehydration step II showed an order of reaction equal to five. This change in reaction order was attributed to loss of chemically bonded water molecules of phytic acid or to the presence of volatile substances. Finally, the thermal decomposition step revealed an order of reaction equal to one. It was not possible to perform the kinetic study for other stages of mass loss.

One new and three already described azobased methacrylate monomers with methoxy and nitro end groups and spacer length 2 and 6 were synthesized. These monomers were copolymerized with methyl methacrylate and the monomers as well as copolymers were characterized by classical spectroscopy techniques (FTIR, NMR, and UV‐VIS), gel permeation chromatography (GPC), elemental analysis and thermal analysis (TGA and DSC). The glass transition temperature of the polymers was found to be above room temperature and thermal decomposition temperatures above 100°C. All the polymers were amorphous in nature and formed excellent homogeneous films with good optical transparency. The polymer films coated on indium tin oxide glass slides were poled and their order parameters were calculated to check the stability of oriented dipoles. Few samples were also studied for their second harmonic generation properties. Temporal stability, checked up to 120 h at room temperature, was found to be quite satisfactory. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3497–3504, 2007

ABSTRACTPoly(imido-ester-amides) (PIEAs) derived from three new asymmetric dicarboxylic acids containing an imide and ester groups and an aminoacidic moiety (glycine, L-alanine or L-valine) and a wholly aromatic silicon-containing diamine were synthesized according to the Yamazaki method. PIEAs were characterized by spectroscopic methods including 29Si NMR and elemental analysis, and the results were in agreement with the proposed structures. The thermal properties, glass transition temperature (Tg) and thermal decomposition temperature (TDT), were determined and the results showed that both parameters decreased when the aliphatic side chain provides by the amino acids increased, due to the higher free volume between the chains, which minimizes the interactions between them. Two of the PIEAs showed transparency according to the UV-vis spectra, due to that the side chains act as chain spacers, in front of PIEA-a including glycine as aminoacidic moiety, without side aliphatic group, which did not show transparence.

The study was conducted on the modification of bentonite of Navbahor district of Navoi region of the Republic of Uzbekistan in chloride, sulfuric and nitric acids and their boiling point. Modified samples were analysed by IR-spectroscopic, X-ray phase, elemental and electronmicroscopic analysis methods. Morphology, specific surface structures and spatial composition of bentonite powder found in Navbahor were studied. Mechanical processing was carried out in a planetary mill. The aim of the study is to investigate the mechanical effects and the effects of acidic processing on the structure and composition of bentonite, its structure and physicochemical properties. The following methods of inspection were used: scanning electron microscopy (SEM), X-ray structural analysis, Brunauera - Emmeta - Taylor (BET), method laser beam diffraction and element analysis. It was shown that in the first 60 minutes of mechanical processing, a further grinding of the powder was carried out in a planetary mill, with an increase in the specific surface area of 33m2/g. Subsequent mechanical activation resulted in particle agglomeration and shrinkage of the specific surface area.