scholarly journals The study of the modification methylphenylsiloxane resin with dimethylene links metal compounds and boric acid

2019 ◽  
Vol 59 (8) ◽  
pp. 78-85
Author(s):  
Andrey M. Kontorov ◽  
◽  
Boris B. Sergeev ◽  
Keyword(s):  
Boric Acid ◽  
Room Temperature ◽  
Main Chain ◽  
Raw Materials ◽  
Argon Atmosphere ◽  
29Si Nmr ◽  
Metal Compounds ◽  
29Si Nmr Spectra ◽  
Acidolysis Reaction ◽  
Thermal Stability Of

In this paper we study the effect of modified metal compounds and boric асid (E), where Element = B, Ti, Zr, Al on the thermal stability of methylphenylsiloxane resins derived from alkoxysilanes. Currently interested in the reaction for producing oligosilsesquioxanes based on acidolysis alkoxysilanes. In this regard, the author was tasked with obtaining new methylphenylsiloxane resins with different properties. In this paper, we study the properties of new methylphenylsiloxane resins (MFSS), modified metal compounds and boric acid. New MFSS obtained by a new universal technology-acidolysis mixture of methyltriethoxysilane (MTEOS) and phenyltriethoxysilane (PHTEOS) with various radicals, which are environmentally friendly raw materials. The obtained MFSS were characterized by NMR spectroscopy on 1H and 29Si nuclei. The spectra were recorded at room temperature in deuteroacetone using a Bruker AM-360 Fourier spectrometer. 29Si NMR spectra were measured using the pulse program "Inverse Gated Heteronuclear Decoupling". Thermogravimetric analysis was performed on the device Derivatograph-H (firm Mom). TGA studies were carried out in the argon atmosphere and in air at a heating rate of 10 ºC/min. The acidolysis reaction of methyltriethoxysilane and phenyltriethoxysilane is a convenient and versatile method for the synthesis of new heat-resistant methylphenylsiloxane resins. In the course of the study, it was found that the resins obtained on the basis of organoalkoxysilanes are characterized by higher thermal and thermo-oxidative stability. It is shown that the modification methylphenylsiloxane resin dimethylsiloxane links in the main chain elementlocalname fragments of ≡Si-O-Element-O-Si≡, where element = B, Ti, Zr, Al increases its resistance to the level methylphenylsiloxane resin without dimethylsiloxane links.

scholarly journals New methylphenylsiloxane resin based on alkoxysilanes

2019 ◽  
Vol 59 (7) ◽  
pp. 142-149
Author(s):  
Andrey M. Kontorov ◽  
Keyword(s):  
Kinematic Viscosity ◽  
Room Temperature ◽  
Raw Materials ◽  
Argon Atmosphere ◽  
29Si Nmr ◽  
Synthesis Conditions ◽  
Residual Functional ◽  
29Si Nmr Spectra ◽  
Hydroxy Groups

Currently interested in the reaction for producing oligosilsesquioxanes based on acidolysis alkoxysilanes. In this regard, the author was given the following tasks: development of optimal synthesis conditions; preparation of new methylphenylsiloxane resins with different properties. In this paper, the properties of new methylphenylsiloxane resins (MPR) with various radicals in silicon were studied. New IFSS were obtained by a new universal technology-acidolysis of a mixture of methyltriethoxysilane (MTEOS) and phenyltriethoxysilane (PTEOS) with various radicals, which are environmentally friendly raw materials. The obtained MPR were characterized by NMR spectroscopy on 1H and 29Si nuclei. Spectra were recorded at room temperature in deuteroacetone using Bruker AM-360 Fourier spectrometer. 29Si NMR spectra were measured using the pulse program "Inverse Gated Heteronuclear Decoupling". The content of residual functional groups (Si-OH, Si-OEt) in IFSS was determined by functional analysis methods. Determination of ethoxy groups and hydroxy groups was carried out by iodometric and aluminohydride method, respectively. Thermogravimetric analysis was performed on the device Derivatograph-H (firm Mom). TGA studies were carried out in the argon atmosphere and in the air at a heating rate of 10 ºC/min. Measurements of kinematic viscosity of 20 % and 50% by weight. toluene solutions of MPR were carried out at 20 °C on the viscometer HPV-2. The reaction acidolysis of methyltriethoxysilane and oligophenylenes is a convenient and versatile method for the synthesis of new heat-resistant resins methylphenylsiloxanes. In the course of the study, it was found that the resins obtained on the basis of organoalkoxysilanes are characterized by higher thermal and thermo-oxidative stability.

New Polymer Syntheses IV. Synthesis and Characterization of New Polyamides Containing Bis-Benzthiazolyl Sulphone Units in the Main Chain

1996 ◽  
Vol 8 (2) ◽  
pp. 307-314 ◽  
Author(s):  
Kamal I Aly ◽  
Maymona M Kandeel
Keyword(s):  
Room Temperature ◽  
Model Compound ◽  
Main Chain ◽  
H Nmr ◽  
Dsc Measurements ◽  
Elemental Analyses ◽  
Tga And Dsc ◽  
Thermal Stability Of ◽  
Solution Polycondensation

Bis(2-aminobenzthiazolyl) sulphone (BABS) was used as a new starting material for preparing polyamides. These polyamides were prepared by reacting BABS with adipoyl, sebacoyl, isophthaloyl and terephthaloyl dichlorides, and also with 4,4′-azodibenzoyl chloride or 3,3′-azodibenzoyl chloride, utilizing the solution polycondensation technique at low temperature. In addition, the model compound was synthesized by condensing the BABS with benzoyl chloride. Characterization of the monomer, model compound and the polyamides was accomplished by 1H NMR, IR and elemental analyses. The polyamides had reduced viscosities of 0.25–0.63 dI/g in DMF or DMSO at 25 °C. All the polymers dissolved readily at room temperature in polar aprotic solvents. The thermal stability of the polymers was evaluated by TGA and DSC measurements.

17O, 13C, and 29Si NMR spectra of some acyloxy- and diacetoxysilanes and acetoxygermanes

1986 ◽  
Vol 51 (11) ◽  
pp. 2582-2589 ◽  
Author(s):  
Antonín Lyčka ◽  
Jaroslav Holeček ◽  
Karel Handlíř ◽  
Josef Pola ◽  
Václav Chvalovský
Keyword(s):  
Periodic System ◽  
Time Scale ◽  
Nmr Spectra ◽  
Group Element ◽  
29Si Nmr ◽  
Carboxyl Group ◽  
29Si Nmr Spectra ◽  
Oxygen Atoms

The 17O, 13C, and 29Si NMR spectra of (CH3)3SiOC(O)R, CH3(XCH2)Si(OC(O)CH3)2, and R3GeOC(O)CH3 compounds are reported. In the 17O NMR spectra at 350 K the only signal is observed with the two latter series, but two well-resolved signals are displayed with the (CH3)3SiOC(O)R compounds. The equivalence of both oxygen atoms in carboxyl group on the NMR time scale is discussed from the viewpoint of a possible coordination of the oxygen atoms to the IVB group element of the periodic system.

Preparation of High-Purity Ultrafine α-Al2O3 by Solid-State Reaction at Room Temperature

2008 ◽  
Vol 368-372 ◽  
pp. 683-685
Author(s):  
Cheng Wei Hao ◽  
Bo Lin Wu ◽  
Ji Yan Li
Keyword(s):  
Solid State ◽  
High Purity ◽  
Solid State Reaction ◽  
Room Temperature ◽  
Raw Materials ◽  
Phase Particle ◽  
Phase Transformation Temperature ◽  
Particle Size And Morphology ◽  
Size And Morphology ◽  
Α Al2o3

Ammonium aluminium carbonate hydroxide (AACH), with a small quantity of γ-AlOOH, was synthesized through solid-state reaction at room temperature using AlCl3·6H2O and NH4HCO3 as raw materials and polyethylene glycol (PEG-10000) as the dispersant. After calcined at 1100°C for 1.5h, α-Al2O3 powders with primary particle sizes of 20~30nm were obtained. The crystal phase, particle size and morphology of the high-purity ultrafine α-Al2O3 were characterized. The results showed that a small quantity of γ-AlOOH in the AACH decomposed and formed crystal seeds. The presence of crystal seeds reduced the nucleation activation energy and therefore reduced the phase transformation temperature.

Thermal Breakdown Kinetics of 1-Ethyl-3-Methylimidazolium Ethylsulfate Measured Using Quantitative Infrared Spectroscopy

2017 ◽  
Vol 71 (12) ◽  
pp. 2626-2631 ◽  
Author(s):  
Jeffrey L. Wheeler ◽  
McKinley Pugh ◽  
S. Jake Atkins ◽  
Jason M. Porter
Keyword(s):  
Thermal Stability ◽  
Room Temperature ◽  
Computational Models ◽  
Elevated Temperatures ◽  
Molar Absorptivity ◽  
Ir Absorption ◽  
Optical Cell ◽  
Multiple Samples ◽  
Kinetics Of ◽  
Thermal Stability Of

In this work, the thermal stability of the room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium ethylsulfate ([EMIM][EtSO4]) is investigated using infrared (IR) spectroscopy. Quantitative IR absorption spectral data are measured for heated [EMIM][EtSO4]. Spectra have been collected between 25 ℃ and 100 ℃ using a heated optical cell. Multiple samples and cell pathlengths are used to determine quantitative values for the molar absorptivity of [EMIM][EtSO4]. These results are compared to previous computational models of the ion pair. These quantitative spectra are used to measure the rate of thermal decomposition of [EMIM][EtSO4] at elevated temperatures. The spectroscopic measurements of the rate of decomposition show that thermogravimetric methods overestimate the thermal stability of [EMIM][EtSO4].

Enhanced Thermal Stability of Esterified Lignin in Different Solvent Mediums

2018 ◽  
Vol 9 (1) ◽  
pp. 39-49 ◽  
Author(s):  
Sharifah Nurul Ain Syed Hashim ◽  
Sarani Zakaria ◽  
Chin Hua Chia ◽  
Sharifah Nabihah Syed Jaafar
Keyword(s):  
Thermal Stability ◽  
Alkaline Solution ◽  
Room Temperature ◽  
Hydroxyl Groups ◽  
Aqueous Alkaline Solution ◽  
Alkali Lignin ◽  
Weight Percentage ◽  
H Nmr ◽  
Ft Ir ◽  
Thermal Stability Of

In this study, soda alkali lignin from oil palm empty fruit bunch (EFB-AL) and kenaf core (KC-AL) are esterified with maleic anhydride under two different conditions, namely i) pyridine at temperature of 120°C for 3h and ii) aqueous alkaline solution at room temperature for 4h. As a result, the weight percentage gain (WPG) of the esterified EFB-AL (EFB-EL) and esterified KC-AL (KC-EL) in pyridine demonstrated a higher compared to aqueous alkaline solution. The FT-IR results of EFB-EL and KC-EL in both solvents exhibited some changes at the carbonyl and hydroxyl groups. Furthermore, the esterification process induced the carboxylic peak to appear in both alkali lignin samples. The outcome is confirmed by conducting H-NMR analysis, which demonstrated ester and carboxylic acid peaks within the spectral analysis. Finally, the TGA results showed both EFB-EL and KC-EL that are exposed to aqueous alkaline actually possessed better thermal stability and higher activation energy (Ea) compared to the esterified samples in pyridine.

Utilization of open pit burned household waste ash – a feasibility study in Dhaka

2014 ◽  
Vol 32 (5) ◽  
pp. 397-405
Author(s):  
Md. Obaidul Haque ◽  
Ahmed Sharif
Keyword(s):  
Room Temperature ◽  
Raw Materials ◽  
Bottom Ash ◽  
Open Pit ◽  
Household Waste ◽  
Chemical Compositions ◽  
Muffle Furnace ◽  
Clay Bricks ◽  
Peripheral Area

Informal incineration or open pit burning of waste materials is a common practice in the peripheral area of Dhaka, one of the fastest growing mega-cities in the world. This study deals with the effect of open pit burned (i.e. open burned) household waste bottom ash on fired clay bricks. Between 0 to 50% (by weight) of open pit burned household waste bottom ash was mixed with clay to make bricks. The molded specimens were air-dried at room temperature for 24 h and then oven dried at 100 °C for another 24 h to remove the water. The raw bricks were fired in a muffle furnace to a designated temperature (800, 900 and 1000 °C, respectively). The firing behaviour (mechanical strength, water absorption and shrinkage) was determined. The microstructures, phase compositions and leachates were evaluated for bricks manufactured at different firing temperatures. These results demonstrate that open pit burned ash can be recycled in clay bricks. This study also presents physical observations of the incinerated ash particles and determination of the chemical compositions of the raw materials by wet analysis. Open pit burned ash can be introduced easily into bricks up to 20% wt. The concentrations of hazardous components in the leachates were below the standard threshold for inert waste category landfill and their environmental risk during their use-life step can be considered negligible.

scholarly journals 29Si NMR Chemical Shifts in Crystalline and Amorphous Silicon Nitrides

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1646 ◽  
Author(s):  
Ilia Ponomarev ◽  
Peter Kroll
Keyword(s):  
Silicon Nitride ◽  
Amorphous Silicon ◽  
Density Functional ◽  
Chemical Shifts ◽  
29Si Nmr ◽  
Hydrogenated Silicon ◽  
Nmr Chemical Shifts ◽  
Nmr Data ◽  
29Si Nmr Spectra ◽  
The Impact

We investigate 29Si nuclear magnetic resonance (NMR) chemical shifts, δiso, of silicon nitride. Our goal is to relate the local structure to the NMR signal and, thus, provide the means to extract more information from the experimental 29Si NMR spectra in this family of compounds. We apply structural modeling and the gauge-included projector augmented wave (GIPAW) method within density functional theory (DFT) calculations. Our models comprise known and hypothetical crystalline Si3N4, as well as amorphous Si3N4 structures. We find good agreement with available experimental 29Si NMR data for tetrahedral Si[4] and octahedral Si[6] in crystalline Si3N4, predict the chemical shift of a trigonal-bipyramidal Si[5] to be about −120 ppm, and quantify the impact of Si-N bond lengths on 29Si δiso. We show through computations that experimental 29Si NMR data indicates that silicon dicarbodiimide, Si(NCN)2 exhibits bent Si-N-C units with angles of about 143° in its structure. A detailed investigation of amorphous silicon nitride shows that an observed peak asymmetry relates to the proximity of a fifth N neighbor in non-bonding distance between 2.5 and 2.8 Å to Si. We reveal the impact of both Si-N(H)-Si bond angle and Si-N bond length on 29Si δiso in hydrogenated silicon nitride structure, silicon diimide Si(NH)2.

scholarly journals Preparation and characterization of polyhedral oligomeric silsesquioxane/polystyrene nanocomposites

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Benhong Yang ◽  
Meng Li ◽  
Yun Wu ◽  
Kang Wang
Keyword(s):  
Thermal Stability ◽  
Thermal Property ◽  
Polyhedral Oligomeric Silsesquioxane ◽  
29Si Nmr ◽  
Solution Blending ◽  
Oligomeric Silsesquioxane ◽  
Tga And Dsc ◽  
Thermal Stability Of

AbstractSeveral inorganic/organic nanocomposites were prepared via solution-blending of cage-like octahexyl-polyhedral oligomeric silsesquioxane (Oh-POSS) with polystyrene (PS) in THF solvent. FTIR and 29Si-NMR were employed to characterize the structures of the nanocomposites. SEM pictures showed that the sample films were smooth and no POSS aggregation was observed when POSS content was lower than 1.0 wt%. TGA and DSC were used to investigate the thermal property. The results showed that the incorporation of nanosized Oh-POSS enhanced the thermal stability of PS with low POSS content. When 1.0 wt% of Oh-POSS was incorporated into PS matrix, the Tg and Td increased by 7.7 °C and 8.2 °C, respectively. However, higher POSS contents (>1.0 wt%) would deteriorate the thermal property of the nanocomposites due to the severe congregation of POSS..

Thermal Stability of Ni40Ti40Nb20 and Ni32Ti48Nb20 Tapes Obtained by Rapid Solidification Technique

2012 ◽  
Vol 188 ◽  
pp. 41-45
Author(s):  
György Thalmaier ◽  
Ioan Vida-Simiti ◽  
N. Jumate ◽  
Viorel Aurel Şerban ◽  
C. Codrean ◽  
...  
Keyword(s):  
Thermal Stability ◽  
High Purity ◽  
Elevated Temperatures ◽  
Graphite Crucible ◽  
Argon Atmosphere ◽  
Membrane Reactors ◽  
Master Alloys ◽  
Selective Membrane ◽  
Dta Analysis ◽  
Thermal Stability Of

Nickel–titanium- group 5A metal (V, Nb, Ta, Zr) alloys are known as promising hydrogen-selective membrane materials. They can potentially be used in membrane reactors, which can produce high-purity H2 and CO2 streams from coal-derived syngas at elevated temperatures. The master alloys were prepared by arc melting using high purity metals in a Ti-gettered argon atmosphere. The alloys were melted several times in order to improve homogeneity. The ingots were induction-melted under a high-purity argon atmosphere in a quartz tube and graphite crucible injected through a nozzle onto a Cu wheel to produce rapidly solidified amorphous ribbons. Thermal stability of the Ni40Ti40Nb20 and Ni32Ti48Nb20 thin tapes has been examined using DTA analysis.

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