scholarly journals The effect of temperature, time of curing and Na2O/SiO2 molar ratio on mechanical and chemical properties of geopolymer cement

10.30544/454 ◽  
2020 ◽  
Author(s):  
Amir Dehnavi ◽  
Masoud Rajabi ◽  
Fatemeh Bavarsiha
Keyword(s):  
Chemical Properties ◽  
High Strength ◽  
Magic Angle Spinning ◽  
Raw Material ◽  
Curing Temperature ◽  
Effect Of Temperature ◽  
Molar Ratio ◽  
Magic Angle ◽  
Suitable Alternative ◽  
Geopolymer Cement

The geopolymer cement is a suitable alternative material for Portland cement due to their environmental compatibility, low curing temperature, and high strength. In this research, Kaolin was used as a raw material for the construction of a geopolymer cement, while sodium hydroxide was an alkali hydroxide. Kaolin is calcined at 750 °C to obtain meta-kaolin. Geopolymer samples were prepared at various curing temperatures (25, 50, and 75 °C), different curing times (3, 7, 21, 28, and 60 days) and with different activator ratios (0.6-0.9). The thermal analysis of kaolin was done via DTA/TGA. Investigation on the geopolymer cement structure and phases were performed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and magic angle spinning nuclear magnetic resonance (MAS-NMR). Also, the effects of temperature and time of curing and Na2O/SiO2 molar ratio were studied. The results showed that the maximum compressive strength was 115MPa, which obtained at a molar ratio of Na2O/SiO2=0.9, a curing time of 60 days, and a curing temperature of 75°C. The microstructure of cement was studied using scanning electron microscopy (SEM).

scholarly journals Synthesis and thermal properties of some phenolic resins

2019 ◽  
Vol 7 (1) ◽  
pp. 1-15
Author(s):  
Alshawi F M ◽  
Abdul Razzq K ◽  
Hanoosh W S
Keyword(s):  
Phenol Formaldehyde ◽  
Chemical Properties ◽  
Decomposition Temperature ◽  
Industrial Applications ◽  
Stability Study ◽  
Curing Temperature ◽  
Molar Ratio ◽  
Scanning Calorimetry ◽  
Phenolic Resins ◽  
Physical And Chemical

Introduction: Phenolic resins have been in use since the early twentieth century and are considered the first class of synthetic polymers to achieve commercial success, moreover phenolic resins continue to succeed and attract special interest in a large range of industrial applications such as adhesives, paints, and composites; because of their unique physical and chemical properties. Materials and Methods: Prepolymers resol resins (RR, RH, RP, and RC) were synthesized by the reaction of phenolic compounds (resorcinol, hydroquinone, phloroglucinol, and catechol) respectively, with formaldehyde at molar ratio phenol/ formaldehyde 1/1.5, using sodium hydroxide as a catalyst. These resins were characterized by FTIR. The curing reaction of these resins was evaluated using differential scanning calorimetry (DSC), while the thermal stability study was evaluated using thermogravimetric analysis (TGA). Results and Discussion:From the results showing that these prepolymers have different curing temperatures and curing energy, while the TGA study showed that the cured resins have decomposition temperature more than 300 ºC, and char residue at 650 ºC more than 60%. Conclusions: These resol resins have different gel times (8-55) min, and viscosities (435-350) mpa.s. The curing temperature of these resin obtained from DSC curves was (120, 129, 105 and 127 °C), while the thermal behavior of the cured resins obtained from TGA curves showed that these cured resin have two decomposition temperatures and the rate of decomposition in the order of RC < RR< .

scholarly journals PELATIHAN PEMBUATAN BRIKET DARI ARANG TEMPURUNG KELAPA DI KELURAHAN KOLONGAN SATU KOTA TOMOHON

2018 ◽  
Vol 10 (01) ◽  
Author(s):  
Meytij J Rampe
Keyword(s):  
Carbon Material ◽  
Chemical Properties ◽  
Raw Material ◽  
Coconut Shell ◽  
Process Synthesis ◽  
Effect Of Temperature ◽  
Synthesis Process ◽  
Product Characteristics ◽  
Structural Growth

Training on the briquettes synthesis from coconut shell charcoal has been conducted. This training was aimed to study the effects starch agent in the from solution on structural growth of briquettes and its chemical properties and the effect of temperature (200-500 oC) on the characters of the briquettes. The product characteristics of briquettes showed thatthere was a change on the chemical properties of the raw material which has been sintered at 300 oC, at which briquettes was produced in this process. Synthesis process at 300 oC in the presence of starch gave carbon material briquettes.

Effects of Preparation Conditions on Alkali-Activation Reactivity of Chemosynthetic Al2O3-2SiO2 Powders

2015 ◽  
Vol 1120-1121 ◽  
pp. 123-127
Author(s):  
Dong Huang ◽  
Wan Li Lu ◽  
Jin Ying Pang ◽  
Guo Wei Mo ◽  
Shu Juan Yu ◽  
...  
Keyword(s):  
Calcination Temperature ◽  
Sol Gel ◽  
Magic Angle Spinning ◽  
Molar Ratio ◽  
Alkali Activation ◽  
Magic Angle ◽  
Drying Time ◽  
Preparation Conditions ◽  
Key Factor ◽  
Synthetic Temperature

Pure Al2O3-2SiO2 powders with alkali-activation reactivity were prepared by a sol-gel method. The effects of preparation conditions on alkali-activation reactivity were studied and the optimum preparation conditions were obtained. The results show that calcination temperature is a key factor affecting the alkali-activation reactivity of the powders, while other preparation conditions such as synthetic temperature, the molar ratio of solvents to starting materials and drying time have fewer effects on alkali-activation reactivity than calcination temperature. The structure of the powders was investigated by 27Al magic-angle spinning nuclear magnetic resonance spectra. The data show that the Al2O3-2SiO2 powders with the high alkali-activation reactivity are of high content of 5-coordinated Al and the peaks attributed to 5-coordinated Al are strengthened with the rise of calcination temperature of the powders.

Effects of interaction between montmorillonite and Sphingomonas sp. GY2B on the physical and chemical properties of montmorillonite in the clay-modulated biodegradation of phenanthrene

2018 ◽  
Vol 15 (5) ◽  
pp. 296 ◽  
Author(s):  
Bo Ruan ◽  
Pingxiao Wu ◽  
Huimin Wang ◽  
Liping Li ◽  
Langfeng Yu ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Structural Changes ◽  
Morphological Changes ◽  
Chemical Properties ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Valuable Insight ◽  
Physical And Chemical Properties ◽  
Physical And Chemical ◽  
And Chemical Properties

Environmental contextInteractions between microbes and minerals can influence geochemical reactions, and hence are of fundamental importance in natural environmental processes. We investigate the effects of Sphingomonas sp. on the structure and physicochemical properties of montmorillonite, a common clay mineral, and determine how this interaction influences the biodegradation of phenanthrene. The findings have profound impact on the clay-modulated biodegradation of organic compounds in the environment. AbstractWe investigate the effect of Sphingomonas sp. GY2B on the structure and physicochemical properties of montmorillonite (Mt). The simultaneous biodegradation of a polycyclic aromatic hydrocarbon compound, phenanthrene, was also monitored. After interaction with bacteria for 2 days, the increases of the specific surface area (SSA) and micropore volume, differences of the thermogravimetric analysis and differential scanning calorimetry (TGA-DSC) patterns and the morphological changes revealed modification of the physicochemical properties and mineral surface. Although the interlayer spacing of Mt remained unchanged, the appearance and shift of several vibration peaks in the Fourier transform infrared (FTIR) spectra confirmed the structural changes of Mt arising from bacterial activities. Concentrations of the major elements of montmorillonite changed greatly in the aqueous solution, especially Si, Al, Fe and Ca. Based on the analyses of X-ray diffraction (XRD) and FTIR, these changes were mainly ascribed to the formation of precipitates and minerals in the biotic experiment. Changes in the release rate of different elements also substantiated that the GY2B strain has a considerable impact on the dissolution of montmorillonite. Additionally, a preferential release of Si and the 27Al and 29Si cross-polarisation magic-angle spinning nuclear magnetic resonance (CP/MAS NMR) spectra of bacteria-untreated samples demonstrated that tetrahedral sheets were preferentially destroyed and octahedral sheets in montmorillonite were dissolved. These results showed that microorganisms can greatly affect the physical and chemical properties of clay minerals in the clay-modulated biodegradation of hydrophobic organic contaminants. This study provides valuable insight into the clay-modulated microbial remediation of organic pollutants in the environment.

scholarly journals Solid-State 13C NMR Spectroscopy Applied to the Study of Carbon Blacks and Carbon Deposits Obtained by Plasma Pyrolysis of Natural Gas

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Jair C. C. Freitas ◽  
Daniel F. Cipriano ◽  
Carlos G. Zucolotto ◽  
Alfredo G. Cunha ◽  
Francisco G. Emmerich
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Natural Gas ◽  
Nmr Spectra ◽  
Plasma Reactor ◽  
Chemical Properties ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Carbon Deposits ◽  
Different Types

Solid-state 13C nuclear magnetic resonance (NMR) spectroscopy was used in this work to analyze the physical and chemical properties of plasma blacks and carbon deposits produced by thermal cracking of natural gas using different types of plasma reactors. In a typical configuration with a double-chamber reactor, N2 or Ar was injected as plasma working gas in the first chamber and natural gas was injected in the second chamber, inside the arc column. The solid residue was collected at different points throughout the plasma apparatus and analyzed by 13C solid-state NMR spectroscopy, using either cross polarization (CP) or direct polarization (DP), combined with magic angle spinning (MAS). The 13C CP/MAS NMR spectra of a number of plasma blacks produced in the N2 plasma reactor showed two resonance bands, broadly identified as associated with aromatic and aliphatic groups, with indication of the presence of oxygen- and nitrogen-containing groups in the aliphatic region of the spectrum. In contrast to DP experiments, only a small fraction of 13C nuclei in the plasma blacks are effectively cross-polarized from nearby 1H nuclei and are thus observed in spectra recorded with CP. 13C NMR spectra are thus useful to distinguish between different types of carbon species in plasma blacks and allow a selective study of groups spatially close to hydrogen in the material.

scholarly journals Polydisperse methyl β-cyclodextrin–epichlorohydrin polymers: variable contact time 13C CP-MAS solid-state NMR characterization

2015 ◽  
Vol 11 ◽  
pp. 2785-2794 ◽  
Author(s):  
Isabelle Mallard ◽  
Davy Baudelet ◽  
Franca Castiglione ◽  
Monica Ferro ◽  
Walter Panzeri ◽  
...  
Keyword(s):  
Solid State ◽  
Contact Time ◽  
Magic Angle Spinning ◽  
Proton Spin ◽  
Fine Tuning ◽  
Spin Lattice Relaxation ◽  
Molar Ratio ◽  
Magic Angle ◽  
Cross Polarization ◽  
Nmr Characterization

The polymerization of partially methylated β-cyclodextrin (CRYSMEB) with epichlorohydrin was carried out in the presence of a known amount of toluene as imprinting agent. Three different preparations (D1, D2 and D3) of imprinted polymers were obtained and characterized by solid-state 13C NMR spectroscopy under cross-polarization magic angle spinning (CP-MAS) conditions. The polymers were prepared by using the same synthetic conditions but with different molar ratios of imprinting agent/monomer, leading to morphologically equivalent materials but with different absorption properties. The main purpose of the work was to find a suitable spectroscopic descriptor accounting for the different imprinting process in three homogeneous polymeric networks. The polymers were characterized by studying the kinetics of the cross-polarization process. This approach is based on variable contact time CP-MAS spectra, referred to as VCP-MAS. The analysis of the VCP-MAS spectra provided two relaxation parameters: T CH (the CP time constant) and T 1ρ (the proton spin-lattice relaxation time in the rotating frame). The results and the analysis presented in the paper pointed out that T CH is sensitive to the imprinting process, showing variations related to the toluene/cyclodextrin molar ratio used for the preparation of the materials. Conversely, the observed values of T 1ρ did not show dramatic variations with the imprinting protocol, but rather confirmed that the three polymers are morphologically similar. Thus the combined use of T CH and T 1ρ can be helpful for the characterization and fine tuning of imprinted polymeric matrices.

The effect of temperature on the 29Si magic angle spinning n.m.r. spectrum of highly siliceous ZSM-5

1985 ◽  
pp. 740 ◽  
Author(s):  
Colin A. Fyfe ◽  
Gordon J. Kennedy ◽  
George T. Kokotailo ◽  
James R. Lyerla ◽  
William W. Fleming
Keyword(s):  
Magic Angle Spinning ◽  
Effect Of Temperature ◽  
Magic Angle ◽  
Angle Spinning

scholarly journals Residue-specific insights into (2x)72 kDa tryptophan synthase obtained from fast-MAS 1H-detected solid-state NMR

2021 ◽  
Author(s):  
Alexander Klein ◽  
Petra Rov&oacute ◽  
Varun V. Sakhrani ◽  
Yangyang Wang ◽  
Jacob Holmes ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Chemical Properties ◽  
Magic Angle Spinning ◽  
Precise Determination ◽  
Magic Angle ◽  
Tryptophan Synthase ◽  
Recent Developments ◽  
Angle Spinning ◽  
Fast Magic Angle Spinning

Solid-state NMR has emerged as a potent technique in structural biology, suitable for the study of fibrillar, micro-crystalline, and membrane proteins. Recent developments in fast-magic-angle-spinning and proton-detected methods have enabled detailed insights into structure and dynamics, but molecular-weight limitations for the asymmetric part of target proteins have remained at ~30-40 kDa. Here we employ solid-state NMR for atom-specific characterization of the 72 kDa (asymmetric unit) microcrystalline protein tryptophan synthase, an important target in pharmacology and biotechnology, chemical-shift assignments of which we obtain via higher-dimensionality, 4D and 5D solid-state NMR experiments. The assignments for the first time provide comprehensive data for assessment of side chain chemical properties involved in the catalytic turnover, and, in conjunction with first-principles calculations, precise determination of thermodynamic and kinetic parameters is demonstrated for the essential acid-base catalytic residue βK87. The insights provided by this study expand by nearly a factor of two the size limitations widely accepted for NMR today, demonstrating the applicability of solid-state NMR to systems that have been thought to be out of reach due to their complexity.

Precipitation and Characterization of an Aluminosilicate from ALCL3-Na2SiO3-HCL in Serum, of Interest for Alzheimer Disease

1992 ◽  
Vol 38 (10) ◽  
pp. 2019-2024 ◽  
Author(s):  
H Bilinski ◽  
L Horvath ◽  
M Trbojevic-Cepe
Keyword(s):  
Alzheimer Disease ◽  
Human Serum ◽  
Serum Proteins ◽  
Aluminum Toxicity ◽  
Sodium Dodecyl ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Molar Ratio ◽  
Magic Angle ◽  
Albumin Ratio

Abstract A precipitation experiment was performed with human serum to model aluminosilicate formation in brains of patients with Alzheimer disease. Aluminum and (or) silicate ions were added to serum in a 1:2 molar ratio at pH 7.4. Precipitates formed immediately and were left for 24 h at 37 degrees C before filtration. Silicate and aluminosilicate formed precipitates with human serum proteins albumin, transferrin, and IgG. In untreated samples, the IgG/albumin ratio increased slightly compared with the ratio in dried serum. Diethylbarbiturate-washed precipitates had a significantly lower protein content than did untreated ones. The IgG/albumin ratio increased considerably in the sample containing aluminosilicate. We conclude that IgG is the sodium dodecyl sulfate-soluble human protein most firmly bound to the aluminosilicate matrix. From 27Al magic-angle-spinning nuclear magnetic resonance (MAS NMR), a pronounced peak was found at 52.79 ppm and a minor peak at 0.53 ppm, suggesting that 4-coordinated aluminum predominates and that 6-coordinated aluminum is present in a smaller proportion. The 29Si MAS NMR spectrum shows a poorly ordered structure. The aluminosilicate formed also contains the cations Na+ &gt; K+ &gt; Ca2+ &gt; Mg2+ and anions Cl- &gt; PO4(3-). Rather than looking for aluminum toxicity to explain the effects of Alzheimer disease, one should consider that by precipitating such a composite phase, the balance of cations, anions, and proteins in human serum is changing.

scholarly journals Formation and characterization of calcium silicate hydrate–hexadecyltrimethylammonium nanostructure

2008 ◽  
Vol 23 (10) ◽  
pp. 2804-2815 ◽  
Author(s):  
James J. Beaudoin ◽  
Harouna Dramé ◽  
Laila Raki ◽  
Rouhollah Alizadeh
Keyword(s):  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Peak Position ◽  
Magic Angle Spinning ◽  
Curing Temperature ◽  
Magic Angle ◽  
Sem Images ◽  
Pre Treatment ◽  
Angle Spinning ◽  
The Stability

Results of an investigation of the interaction potential of synthetic and pre-treated calcium silicate hydrate (C-S-H) [with hexadecyltrimethylammonium (HDTMA)] are reported. The effective and strong interaction of these molecules with the C-S-H surface was shown using 13C and 29Si cross polarization magic angle spinning (CP MAS) nuclear magnetic resonance, x-ray diffraction, thermogravimetric analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy analysis. The HDTMA–C-S-H interaction is influenced by the poorly crystallized layered structure of C-S-H. An indefinite number of layers and an irregular arrangement are confirmed by the SEM images. The position and shape of the 002 reflection of C-S-H are affected by drying procedures, chemical pre-treatment, and reaction temperature. Recovery of the initial 002 peak position after severe drying and rewetting with distilled water or interaction with HDTMA is incomplete but accompanied by an increase in intensity. It is inferred that the stability of C-S-H binders in concrete can be affected by a variation in nanostructure resulting from engineering variables such as curing temperature and use of chemical admixtures.

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