Chemical approach to the glass structure and properties

Vitrification has been recognized as the best method of the neutralization and immobilization of the radioactive and toxic wastes. Toxic elements are introduced into the structure of chemically durable glasses (waste glasses). Radioactive 137Cs is a dangerous contaminant of hospital and laboratory wastes. Incineration of these waste followed by vitrification of the ashes by co-melting them with borosilicate glass is a prospective method of immobilization of 137Cs for safety waste storage. The influence of partial substitution of Na by Cs and introduction of CaO as the main component of the hospital waste incineration ash on the structure, crystallization ability, and physical properties of SiO2-B2O3 -Al2O3-Na2O glass was studied. It was established that due to crystallochemical differences between Cs+ and Na+ as the glass structure modifiers, in the presence of even a relatively small amount of Cs2O (5 mass %) the degree of polymerization of the glass network and its stability increases which means, simultaneously the increase of the chemical durability of the glass. On the other hand above glass transformation temperature (Tg), cesium acts as the strong depolymeriser of network, increasing the tendency for crystallization of the basic glass. It becomes incorporated into the structure of the newly formed crystal phases such as the chemically resistant aluminosilicates (pollucite, nepheline).

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Hybrid resins from polyisocyanate, vinyl ester, melamine formaldehyde and water glass: structure and properties

Plastics Rubber and Composites ◽

10.1179/174328908x309349 ◽

2008 ◽

Vol 37 (5-6) ◽

pp. 204-209 ◽

Cited By ~ 3

Author(s):

J. Karger-Kocsis ◽

N. Castellà ◽

S. Grishchuk

Keyword(s):

Vinyl Ester ◽

Water Glass ◽

Glass Structure ◽

Structure And Properties ◽

Melamine Formaldehyde

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Influence of Montmorillonite Clay on Structure and Properties of Sodium Borate Glasses

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.39-40.57 ◽

2008 ◽

Vol 39-40 ◽

pp. 57-60

Author(s):

E. Diamanti ◽

A. Lekatou ◽

T. Matikas ◽

M.A. Karakassides

Keyword(s):

Heavy Metals ◽

Borate Glass ◽

Heavy Element ◽

Glass Structure ◽

Chemical Durability ◽

Sodium Borate ◽

Borate Glasses ◽

Structure And Properties ◽

Density Measurements ◽

Ft Ir

In the light of environmental perspective, clay minerals attract special interest because of their capability to absorb and chemically stabilize heavy metals in their structure [1, 2]. The absolute suppression of heavy element leakage from clay structures to the environment, which is obviously a strict demand, can be achieved with clay vitrification. This work is related to the influence of the addition of (0-50 wt%) of montmorillonite to a borate glass with composition of 0.33Na2O-0.67B2O3 on its structure. This influence has been studied with Raman and FT-IR spectroscopies, Archimedean density measurements, chemical durability in 90°C water and finally by studying of the ultrasonically measured elastic properties, such as Young’s and shear modulus and Poisson’s ratio, of the resultant glasses. The experimental results showed that the glass structure is predominantly comprised from tetrahedral and trigonal borate units and silicon and/or aluminium tetrahedral units. The results of density and chemical durability are fairly well correlated with structure. Higher amounts of montmorillonite lead to glasses of higher mechanical strength and chemical durability.

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Effect of MgO on Structure and Properties of CaO-Al2O3-SiO2 Glass System

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.306-307.531 ◽

2011 ◽

Vol 306-307 ◽

pp. 531-534 ◽

Cited By ~ 1

Author(s):

Xing Jun Xu ◽

Yun Long Yue ◽

Hai Tao Zhang ◽

Zhao Du

Keyword(s):

Thermal Analysis ◽

Dielectric Constant ◽

Differential Thermal Analysis ◽

Phase Separation ◽

Glass Structure ◽

Glass Network ◽

Structure Change ◽

Chemical Durability ◽

Structure And Properties ◽

Melt Quenching

CaO-Al2O3-SiO2system glasses with MgO were prepared by melt quenching. The glass structure was characterized by Infrared spectra (IR) and Differential Thermal Analysis (DTA). Dielectric properties, devitrification and chemical durability have been studied. IR spectra and DTA indicated that glass network structure change by doping MgO. The glass chemical improved and dielectric constant decreased after doping with MgO. The glass shows a severe tendency of phase separation.

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A new Experimental Way to Obtain Information about Glass Nano-Heterogeneous Structure

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.39-40.13 ◽

2008 ◽

Vol 39-40 ◽

pp. 13-18

Author(s):

Petru Baltă

Keyword(s):

Calculation Method ◽

Glass Structure ◽

Calculated Data ◽

Heterogeneous Structure ◽

Structure And Properties ◽

Calculation Methods ◽

Technological Parameters ◽

Charge Transfer Transition ◽

Long Time

The heterogeneous character of the glass structure is, from long-time, in the attention of researchers. Some calculation methods for obtaining information concerning the nature and distribution of nano aggregates in glass were published in the middle of the 20th century. The experimental methods borrowed from other fields of chemistry are hardly useful the results are mostly qualitative and their use to select the calculation method giving closer to reality data is practically impossible. For these reasons, a new combined experimental and calculation method was imagined, allowing the obtainment of quantitative data about the concentration and distribution of nano-aggregates in glasses. By means of the method for experimental determination of the basicity of glass, with Cu2+ as probe ion, relationships were deduced allowing obtaining the composition and the amount of each nano-aggregate in glass from the recorded maximum of the charge transfer transition absorption. The results obtained for some silicate glasses, compared with the theoretical calculated data, seem to validate this approaching way. By means of the new experimental method, the direct following of the technological parameters influence on glass structure and properties become possible.

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