Structural Thermodynamic Model for the Durability and Viscosity of Nuclear Waste Glasses

1987 ◽  
Vol 112 ◽  
Author(s):  
Xiangdong Feng ◽  
Aaron Barkatt
Keyword(s):  
Nuclear Waste ◽  
Composition Dependence ◽  
Glass Composition ◽  
Chemical Properties ◽  
Test Results ◽  
Structural Rules ◽  
Predominant Factor ◽  
Alkali Oxides ◽  
Bond Strengths ◽  
And Chemical Properties

AbstractA model based upon structural thermodynamic considerations has been proposed for both chemical durability and viscosity of nuclear waste glasses. This model assumes the bond strength between atoms in the glass to be the predominant factor in controlling the composition dependence of physical properties such as viscosity and chemical properties like durability. These characteristic bond strengths in the glass are obtained from known heats of formation of the constituent oxides with a few simple structural rules deduced by distinguishing the structural roles of the various oxides, i.e., separating those components that are clearly “network-formers” (e.g. SiO2, Al2O3, ZrO2) from those that are clearly “network-breakers” (e.g. alkali oxides). This model has been successfully applied to the correlation of glass composition with modified MCC-3 leach test results on nuclear waste glasses measured at various laboratories on one hand and with the viscosities of numerous glasses over a temperature range of 850°C to 1600°C with remarkable accuracy on the other hand.

scholarly journals Performance Study of Grass-Derived Nano-Cellulose and Polycaprolactone Composites for 3D Printing

2021 ◽  
Vol 11 (3) ◽  
pp. 1273
Author(s):  
Chen Feng ◽  
Jiping Zhou ◽  
Xiaodong Xu ◽  
Yani Jiang ◽  
Hongcan Shi ◽  
...  
Keyword(s):  
3D Printing ◽  
Mechanical Test ◽  
Chemical Properties ◽  
Test Results ◽  
Performance Study ◽  
Compression Process ◽  
Ansys Fluent ◽  
Nano Cellulose ◽  
Physical And Chemical ◽  
And Chemical Properties

In recent years, 3D printing has received increasing attention from researchers. This technology overcomes the limitations of traditional technologies by printing precise and personalized scaffold with arbitrary shapes, pore structures, and porosities for the applications in various tissues. The cellulose nanocrystal (CNC) is extracted from Humulus Japonicus (HJS) and mixed with poly(ε-caprolactone) (PCL) to prepare a series of CNC/PCL composites for printing. Based on the analysis of the physical and chemical properties of the series of the CNC/PCL composites, an optimal mass ratio of CNC to PCL was obtained. The Solidworks was used to simulate the stretching and compression process of the scaffolds with three different patterns under an external force. The flow of nutrient solution in the scaffolds with different patterns was simulated by ANSYS FLUENT, and then a new optimization scaffold pattern with a concave hexagon shape was advised based on the simulation results. Collectively, the mechanical test results of the material and scaffold confirmed that the optimal filling amount of the CNC was 5%, and the scaffold pattern with concave hexagon shape exhibited better mechanical properties and suitable for the transport of cells and nutrients, which is expected to be more widely used in 3D printing.

scholarly journals Effect of Nano Charcoal Ash Coconut Shell in Bitumen as Alternative Binder

2019 ◽  
Vol 8 (3S3) ◽  
pp. 517-523
Keyword(s):  
Softening Point ◽  
Performance Test ◽  
Chemical Properties ◽  
Coconut Shell ◽  
Size Analysis ◽  
Test Results ◽  
Median Particle ◽  
Physical And Chemical ◽  
Grinding Time ◽  
And Chemical Properties

The effect of Nano charcoal ash (NCA) from coconut shell on the physical and chemical properties of bitumen as alternative binder was evaluated in this study. Six different Nano grades of charcoal ash were examined. The charcoal ash ground for the optimum grinding time had a median particle size of 148 nm. NCA dosage of 30% by weight of binder was used throughout the experiments. Nanoparticle size analysis and X-ray fluorescence were performed to determine the size and chemical properties of material. Dynamic shear rheometer, penetration, softening point, and penetration index were used to characterize the physical properties of NCA. Thirty hours of grinding time produced the optimum NCA, which could enhance the binder performance. Test results indicated that adding NCA from coconut shell to bitumen improved the binder stiffness up to 47% and significantly increased the softening point up to 12% compared with virgin binder.

The nature of the sulphur-oxygen bond

1950 ◽  
Vol 200 (1062) ◽  
pp. 409-428 ◽  
Keyword(s):  
Molecular Orbital ◽  
Electronic Structures ◽  
Chemical Properties ◽  
Orbital Method ◽  
Physical And Chemical Properties ◽  
Bond Strengths ◽  
Set Up ◽  
Physical And Chemical ◽  
Oxygen Bond ◽  
And Chemical Properties

The electronic structures of certain molecules containing oxy-sulphur bonds are analyzed insome detail by means of the molecular orbital method. I t is possible to make rough calculations which, despite the complexity of the system s considered, are nevertheless reasonably reliable. The physical and chemical properties of sulphur dioxide, sulphur trioxide and molecules of the types R 2 SO 2 and R 2 SO are discussed on the basis of these structures. In all these molecules it appears that the oxy-sulphur linkages are best described as double-bonded. A successful correlation between the molecular orbital criterion of bond strengths, namely, the bond orders, and the oxy-sulphur bond force constants may be set up. The measure of agreement attained between observed and predicted properties is quite satisfactory.

scholarly journals Physical-Chemical Characteristics of South Aceh Marble and Its Suitability for Tiles Application

2020 ◽  
Vol 5 (1) ◽  
pp. 1
Author(s):  
Lindawati Lindawati ◽  
Irwansyah Irwansyah ◽  
Nuzuli Fitriadi
Keyword(s):  
Water Absorption ◽  
Construction Material ◽  
Chemical Properties ◽  
Physicochemical Analysis ◽  
Building Stone ◽  
Test Results ◽  
Water Absorption Test ◽  
Natural Stones ◽  
Physical And Chemical ◽  
And Chemical Properties

Marble is a metamorphic rock that is widely distributed in the Earth�s continental layer. Regarding its antiquity and aesthetic appeal, it has been widely used as a construction material such as flooring tiles in buildings and monument. Physical and chemical properties of natural stones play an important role on deciding their application area as a building stone. This study reports the physicochemical analysis of marble stones from the Gunung Kerambil (GK), Alur Kering (AK) and Meukek (M) area in South Aceh District. Density, water absorption and chemical analyses of the marble samples were determined. Physical properties of samples were determined through laboratory measurements. Chemical characterizations were made using X-ray Fluorescence (XRF) method. Based on,water absorption test results, the marbles from South Aceh are applicable for tile application.

scholarly journals The influence of gadolinium on the thermal properties of bioactive glasses

2019 ◽  
Vol 5 (1) ◽  
pp. 193-202 ◽  
Author(s):  
Roger Borges ◽  
Natália Del Rey Menezes ◽  
Juliana Marchi
Keyword(s):  
Thermal Properties ◽  
Essential Role ◽  
Glass Composition ◽  
Chemical Properties ◽  
X Ray Diffraction ◽  
Bioactive Glasses ◽  
X Ray ◽  
Working Temperature ◽  
Re Elements ◽  
And Chemical Properties

Abstract Rare Earth (RE)-containing bioactive glasses has recently gained more relevance in the field of biomaterials due to the unique optical, electronic, and chemical properties of the RE elements. In this work, the influence of gadolinium in the thermal properties of bioactive glasses based on the SiO2-Na2O-CaO-P2O5 containing different Na/Ca ratio was studied. The glasses were obtained by melting-quenching, and their properties were evaluated by differential thermal analysis, X-ray diffraction, and scanning electron microscopy. The results evidenced that Gd tends to increase the working temperature (Tc-Tg) in Ca-rich glasses, which leads to a less tendency to devitrification. On the other hand, in Na-rich glasses, Gd did not play an essential role in crystallization, and the thermal properties of Gd-containing Na-rich glasses were similar to their counterparts. In conclusion, we suggested that it is possible to control the influence of Gd in the glass devitrification by changing the Na/Ca ratio in the glass composition. These results may be interesting for further works to which crystallization may be either a desired or undesired phenomena.

INFLUENCE OF NANOSILICA AND MICROSILICA ON PROPERTIES OF CONCRETE

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Thushara Priyadarshana ◽  
Ranjith Dissanayake
Keyword(s):  
Compressive Strength ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Test Results ◽  
Supplementary Cementing Materials ◽  
Different Ages ◽  
Physical And Chemical ◽  
And Chemical Properties

In this study, supplementary cementing materials (SCM), such as nanosilica and microsilica, have been evaluated for optimal levels of replacement as a blending material in cement. The physical and chemical properties of these materials were first analyzed, then the properties of neat samples, mortar samples, and concrete samples were investigated. Mainly this study focused on the workability and compressive strength with different mixes at different ages of neat, mortar and concrete mixes. Test results obtained in this study indicate that up to 5% nanosilica and 10% of microsilica could be advantageously blended with cement without adversely affecting the strength. However, optimum levels of these materials are 1-3% of nanosilica and 3-8% of microsilica when we consider the strength of concrete.

Effects of Forming Temperature on Structure and Chemical Properties of Calcium Phosphate Cement

2014 ◽  
Vol 910 ◽  
pp. 149-152
Author(s):  
Ching Wen Lou ◽  
Yung Yu Chang ◽  
Ming Chun Sie ◽  
Wen Cheng Chen ◽  
Jia Horng Lin
Keyword(s):  
Calcium Phosphate ◽  
Vapor Pressure ◽  
Calcium Phosphate Cement ◽  
Saturated Vapor Pressure ◽  
Saturated Vapor ◽  
Chemical Properties ◽  
Hydration Reaction ◽  
Test Results ◽  
Forming Temperature ◽  
And Chemical Properties

With similar components to human bone, hydroxyapatite (HAp) has been commonly used in dental and orthopedics practice. Calcium phosphate cement (CPC) can be made into porous HAp scaffolds through reaction; therefore, this study aims to examine how reaction temperatures influence CPC. CPC powder and NaCl are blended, and after diammonium phosphate (DAP) is added, they are infused into a mold for a hydration reaction under a saturated vapor pressure to form CPC scaffolds. XRD and FTIR are used to determine the influence of reaction temperatures on crystallization and functional groups. A scanning electron microscope (SEM) observes the structures of the CPC scaffolds. Test results show that when the temperature of a saturated vapor pressure is 70 °C, the CPC scaffolds have significant crystalline conversion and functional group peaks. SEM observation indicates that the temperature of a saturated vapor pressure does not affect the formation of the CPC scaffolds structure.

Effect of Na2O and K2O on the Solubility and Chemical Properties of P2O5-CaO-Na2O-K2O-Al2O3 Glass

2017 ◽  
Vol 888 ◽  
pp. 146-150 ◽  
Author(s):  
Siti Hafizah Mohamad ◽  
Mohd Al Amin Muhamad Nor
Keyword(s):  
Weight Loss ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Phosphate Glass ◽  
Calcium Ion ◽  
Glass Composition ◽  
Chemical Properties ◽  
Glass System ◽  
And Chemical Properties

The effect addition of Na2O on the solubility properties of phosphate glass of the composition, 45P2O5-18CaO-xNa2O-(34-x)K2O-6Al2O3, where x = 0,5,10,15 and 20 wt. %. has been studied. Glass transition temperature (Tg) of glass samples, weight loss and pH of the immersion solution were measured. The Tg value of the phosphate glass also decreased with the incorporation of Na2O up to 10 wt. % and increased with the incorporation of 15 and 20 wt. %. These results indicates that the solubility and Tg value of phosphate glass were highly influence by the glass composition. The substitution of Na2O to the phosphate glass system with the present of K2O has decrease the solubility of phosphate glass. The released of phosphate and calcium ion seem to decrease with the increasing of Na2O content in the glass composition.

Nuclear Waste Glasses: Continuous Melting and Bulk Vitrification

2008 ◽  
Vol 39-40 ◽  
pp. 633-640 ◽  
Author(s):  
Pavel Hrma ◽  
Albert A. Kruger
Keyword(s):  
Nuclear Waste ◽  
Molten Salts ◽  
Model Development ◽  
Chemical Properties ◽  
Exploratory Research ◽  
Physical And Chemical Properties ◽  
Large Variability ◽  
Waste Vitrification ◽  
Physical And Chemical ◽  
And Chemical Properties

This contribution addresses various aspects of nuclear waste vitrification. Nuclear wastes have a variety of components and composition ranges. For each waste composition, the glass must be formulated to possess acceptable processing and product behavior defined in terms of physical and chemical properties that guarantee that the glass can be easily made and resist environmental degradation. Glass formulation is facilitated by developing property-composition models, and the strategy of model development and application is reviewed. However, the large variability of waste compositions presents numerous additional challenges: insoluble solids and molten salts may segregate; foam may hinder heat transfer and slow down the process; molten salts may accumulate in container refractory walls; on cooling, the glass may precipitate crystalline phases. These problems need targeted exploratory research. Examples of specific problems and their possible solutions are discussed.

scholarly journals Carbon Nanotube Effect on the Ductility, Flexural Strength, and Permeability of Concrete

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Mohamed O. Mohsen ◽  
Mohamed S. Al Ansari ◽  
Ramzi Taha ◽  
Nasser Al Nuaimi ◽  
Ala Abu Taqa
Keyword(s):  
Flexural Strength ◽  
High Performance ◽  
Microstructural Analysis ◽  
Chemical Properties ◽  
Test Results ◽  
Cementitious Composite ◽  
Uniform Dispersion ◽  
Batch Mixing ◽  
Mixing Method ◽  
And Chemical Properties

Recently, remarkable types of carbon nanofilaments called carbon nanotubes (CNTs) have raised the interest of many concrete and cementitious composite researchers due to their significant mechanical, electrical, thermal, kinetic, and chemical properties. These nanofilaments are considered promising applicants to use in producing high-performance cement-based composite materials. In this research, the effect of CNT use on the flexural strength, strain capacity, permeability, and microstructure of concrete was investigated. Concrete batches of 0, 0.03, 0.08, 0.15, and 0.25 wt.% CNTs were prepared using a mixing method that consisted of a 30-minute solution sonication and a 60-minute batch mixing. On the 28th day, the mechanical properties were determined. The results indicated that concrete prepared using high CNT contents of 0.15 and 0.25 wt.% increased the flexural strength by more than 100% in comparison with 0% CNT concrete. Furthermore, the results showed that CNTs would increase the ductility of concrete beams by about 150%. The permeability test results showed the benefits of CNT inclusion in reducing the permeability of concrete. The permeability coefficient (kT) decreased by at least 45% when CNTs were added to concrete. A qualitative microstructural analysis illustrated the uniform dispersion of CNT filaments within the concrete hydration products in all batches.

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