Modulus Of Glass Research Articles

Topological constraint model for the elasticity of glass-forming systems

Abstract The elastic response of glass is one of its most important properties for a wide range of applications in architecture, transportation, information display, and healthcare. Unfortunately, there is currently no model to predict quantitatively accurate values of elastic moduli from the underlying network topology of the glass. Here we introduce a topological model to calculate the Young's modulus of glass in terms of the free energy density of rigid constraints in the network. The model shows quantitatively accurate agreement with glasses across a variety of compositional families. More remarkably, the variation of modulus with temperature can also be predicted by accounting for the temperature dependence of the constraints, including the approach to the viscoelastic region near the glass transition.

Investigation on curing characterization of epoxy molding compounds with different latent catalysts by thermal, electrical and mechanical analysis

This research was conducted to investigate comprehensively curing characteristics of epoxy molding compound (EMC) with various latent catalysts by using their thermal, electrical and mechanical properties. The conversion prediction on isothermal condition for three types of organophosphine based catalysts was studied by model free method with differential scanning calorimetry (DSC). The T2 relaxation time was measured by time-domain nuclear magnetic resonance spectroscopy (TD-NMR) in order to compare the cross-linking density for each catalyst according to curing time. The results of DSC and TD-NMR showed that catalysts with lower latency reached curing in a shorter time. Furthermore, we observed the electrical-mechanical characteristics of EMC using additional thermal analysis. The ion viscosity was measured by dielectric analysis (DEA) according to the curing time, and the results suggested that the ion viscosity and the volume resistivity were lower for the catalyst with a slower curing rate. Dynamic mechanical analysis (DMA) was performed to compare activation energy of glass transition and glass modulus of final product. It was shown that the use of a catalyst with a low latency increases the modulus against external physical forces. In conclusion, our results demonstrated that the various analytical approaches are highly significant to understand the curing characteristics of EMC, which helps select appropriate catalysts in order to enhance the reliability of EMC.

Preparation and Performances of Geopolymer-Based Plant Fiber Composites

Geopolymer-based plant fiber composites were fabricated with metakaolin, alkaline sodium silicate and plant fibers. In this paper, orthogonal test and single factor analysis were used to study the influence of water glass modulus, solid liquid ratio and fiber content on bending strength. The results show that sequence of influence factors for bending strength was: solid to liquid ratio > fiber content > water glass modulus. When the water glass modulus is 1.7, the fiber content is 8% and the solid to liquid ratio is 1:1.4, the bending strength is up to 10.44MPa, which exceeds the Standard requirements (9MPa) specified by the China National Standard (GB/T 24312-2009). The micro-morphology of SEM indicates that the mix of plant fiber can enhance the toughness of geopolymer.

Synthesis of high specific surface area silica aerogel from rice husk ash via ambient pressure drying

In this study, silica aerogel was synthesized from rice husk ash-derived water glass through ion-exchange, sol-gel, solvent exchange and ambient pressure drying. The physical and chemical properties of silica aerogel were fully characterized by the Brunauer–Emmett–Teller theory (BET), Field emission scanning electron microscopy (FESEM), Thermogravimetric analysis-differential thermal analysis (TGA-DTA), Fourier transform infrared spectroscopy (FTIR). The effects of processing parameters, especially, the modulus of water glass on the characteristics of the products are deeply investigated. It is found that the modulus of water glass can significantly influence the specific area and pore volume of the aerogel through changing the polymerization degree of SiO group in the water glass solution. As well as, the pH value of sol-gel process and solvent concentration during modification are of importance for the physical properties of silica aerogel. When water glass modulus was 4.26, the gelation pH was 5.0 and the volumetric ratio of Trimethylchlorosilane (TMCS) to n-hexane was 7/50, silica aerogel was obtained with optimal performances of extremely high specific surface area (945.8 m2/g), pore volume (0.889 cm3/g), low density (0.071 g/cm3) uniform pore size distribution, high heat resistance temperature as 400 °C. The presented method is promising to synthesize high specific surface area silica aerogel from rice husk ash.

Network connectivity and properties of non-alkali aluminoborosilicate glasses

The effects of alkaline earth metal oxides (RO) concentrations on the network structure and properties of non-alkali aluminoborosilicate glasses were studied. With the increasing of RO concentrations from 10 to 20mol%, the number of Q4 units decreased, while the number of Q3 units increased. The [AlO4] units always predominated in Al groups, and the fraction of [BO4] among B groups increased from 2% to 10%. Meantime, the value of NBO/T increased from 0.48 to 0.70, indicating the weak network connectivity. The depolymerization of T-O-T network resulted in higher coefficient of thermal expansion, lower temperature of transition point, weaker durability in HF acid. While, the increasing in R2+ cations and [BO4] units led to the higher elastic modulus of glasses. The increasing in RO also enhanced the density, dielectric constant and durability in NaOH solution of glasses.

Degree of Silicic Acid Polymerization in Alkali-Metal Silicate Solutions

The degree of polymerization and the sizes of silicon-oxygen anions in liquid-glass solutions were studied as functions of the silicate modulus, silica density (concentration), and nature of the alkali cation by means of kinematic colorimetry. The degree of polymerization increased appreciably when the modulus increased above 2.6 and density above 1.3. In addition, the liquid glass modulus was the most important factor in the range of the studied characteristics. Above the critical values of the silicate modulus and concentration of the dissolved silicate the system transforms from the true solution of a polyelectrolyte, characterized by the presence of discrete polymer anions, into a coherent-disperse colloidal system with a high degree of volumetric polymerization.

SUSTAINABLE ULTRA-HIGH-PERFORMANCE GLASS CONCRETE FOR INFRASTRUCTURES

This paper presents research work on the development of a green type of ultra-high-performance concrete using ground glass powders with different degrees of fineness (UHPGC). This article presents the development of an innovative, low-cost, and sustainable UHPGC through the use of glass powder to replace cement, and quartz powder particles. An UHPGC with a compressive strength (fc) of up to 220 MPa was prepared and its fresh, and mechanical properties were investigated. The test results indicate that the fresh UHPGC properties were improved when the cement and quartz powder were replaced with non-absorptive glass powder particles. The strength improvement can be attributed to the glass powder’s pozzolanicity and to its mechanical performance (very high strength and elastic modulus of glass). A case study of using this UHPGC is presented through the design and construction of a footbridge. Erection of footbridge at University of Sherbrooke Campus using UHPGC is also presented as a full-scale application.

An Approach for Measurement of Young’s Modulus of Glass in the Form of a Slab

Objectives: The study of elastic properties of material is very important for commercial use as well as for research work. But especially for this purpose we are not always very much interested in study with materials other than metals. Now, there will be a study of elastic property of glass, mainly to determine the value of Young’s Modulus experimentally. Methods/Statistical Analysis: In the present study the process of flexure of a thin beam of glass is used. When external force in the form of weight is applied on the middle point of glass slab, the change in length of different layers of the slab occurs. As a result finally total Internal Bending Moment (IBM) comes to play. Findings: Directly, IBM cannot be measured but at equilibrium it can be treated equal in magnitude to Applied (external) Bending Moment (ABM). Theoretically a relation between ABM and Young’s modulus can be generated, from this study; Young’s modulus can be estimated. The result got from this study is very close to the well-established value of Young’s modulus of glass. Though in the process, the changes in length for glass is very small, breaking load is also very low and regular, symmetric shape of glass is essential, still it is very easy and interesting to determine the value of Young’s modulus of glass. This process not only useful for glass or metals, but can be used for other non-metals. Application/ Improvements: The flexure process may be the quickest and the result very close to the actual result for glass.

Internal friction in chalcogenide glasses Ge-As-Se system in glass transition region

Purpose. The purpose of this work is detecting and determine of mechanisms of relaxation transitions in chalcogenide glasses Ge-As-Se system based on research of temperature dependences of internal friction, shear modulus over a wide temperature range on infralow frequencies. Methods. The temperature dependences of the internal friction and the shear modulus for glasses in the Ge–As–Se system at infralow frequencies of forced torsional vibrations were measured by torsional pendulum method. Results. For all the glasses under investigation, the mechanical losses rapidly increase and, simultaneously, the shear modulus decreases in the range of the glass transition temperature T g . With an increase in the strain frequency, these effects shift toward the high_temperature range, which indicate that the intensive relaxation process proceeds in this temperature range. The parameters U α and τ 0 of this relaxation process were determined from the frequency shift in the hightemperature branch Q –1 ( T ). Conclusions. An increase in the internal friction and the mechanical compliance of glasses in the Ge–As–Se system in the range of the glass transition temperature T g is caused by the activation of the α relaxation process. At Z =2.6, the activation energy of this process increases considerably as a result of the change in the kinetic structural unit responsible for the relaxation process under consideration. α relaxation process occurs as a result of the full defreezing of the mobility of glass structure in T g region.

Preparation and Microstructure Analysis of Fly Ash Geopolymer at Ambient Temperature

A high-strength geopolymer was prepared with fly ash as a raw material by mixing 25% slag and 15% cement at an ambient temperature. The influence law of water glass modulus and alkali activator dosage on geopolymer strength at an ambient temperature was systematically investigated. Results indicated that an alkali activator dosage of 7% to 8% and a sodium silicate modulus of 1.4 to 1.6 are optimal ranges to increase geopolymer strength. In addition, the microstructure of fly ash geopolymer was observed through scanning electron microscopy, X-ray diffraction, and mercury intrusion porosimetry. The relation between the microstructure and mechanical properties of the material was revealed.

Development of ultra-high-performance concrete using glass powder – Towards ecofriendly concrete

A green ultra-high-performance glass concrete (UHPGC) with a compressive strength (fc) of up to 220MPa was prepared and its fresh, mechanical, and microstructural properties were investigated. The test results indicate that the fresh UHPGC properties were improved when the cement and quartz powder were replaced with nonabsorptive glass-powder (GP) particles. The strength improvement can be attributed to the GP’s pozzolanicity and to its mechanical performance (very high strength and elastic modulus of glass). The microscope investigation revealed the formation of a hydration rim around cement and GP particles. UHPGC provides technological, economical, and environmental advantages compared to traditional ultra-high-performance concrete (UHPC).

FTIR spectral analysis and mechanical properties of sodium phosphate glass–ceramics

Glasses of compositions xNa2O–(100−x)P2O5, (40⩽x⩽55) were prepared by melt-quench technique. Controlled heat treatments of these glasses were done to obtain the glass–ceramics. Density of glass–ceramics increases with increasing content of Na2O. X-ray diffraction pattern exhibited two crystalline phases, i.e., NaPO3 and Na2H2P2O7 in all the glass–ceramic samples. FT-IR and Raman study revealed the de-polymerization of phosphate groups, that changes Q2→Q1→Q0 with Na2O content and heat treatment. The scanning electron microscope study confirmed that interlocked crystals are dispersed in a glassy matrix. The Young’s moduli of glass–ceramics are observed in the range of (17.3–21.5)GPa with the increase of Na2O content. The highest value of micro-hardness observed is 918MPa in x=55mol% Na2O glass–ceramic sample. The observed elastic moduli of glass–ceramics are comparable to the other solid electrolyte which is being used in Na-ion batteries.

Influence of Specimen Size on the Impulse Excitation Technique

The Impulse Excitation technique is a nondestructive and very convenient testing method. It could be applied at different circumstances such as high temperatures, low temperatures and controlled humidity. The Impulse Excitation technique is based on the analysis of the vibration of a test sample after it was impulse excited. The elastic properties of a test specimen are related to its mechanical resonance frequency. In this paper, the regular of resonance frequency changed with specimen’s size was discussed. Elastic modulus of glass with different length, width and thickness were measured, and ceramic composite material with small size was tested. The results indicate that the resonance frequency of specimen changed with its size regularly, and the specimen with small size has poor accuracy of elastic modulus measurement.

Shear modulus of glasses: results from the full replica-symmetry-breaking solution.

We compute the shear modulus of amorphous hard and soft spheres, using the exact solution in infinite spatial dimensions that has been developed recently. We characterize the behavior of this observable in the whole phase diagram, and in particular around the glass and jamming transitions. Our results are consistent with other theoretical approaches, which are unified within this general picture, and they are also consistent with numerical and experimental results. Furthermore, we discuss some properties of the out-of-equilibrium dynamics after a deep quench close to the jamming transition, and we show that a combined measure of the shear modulus and of the mean square displacement allows one to probe experimentally the complex structure of phase space predicted by the full replica-symmetry-breaking solution.

Evaluation of Mechanical Properties of Li2S-P2S5-based Glass Electrolytes with Li2O, P2O5 or LiI

Sulfide glasses are expected as solid electrolytes for all-solid-state batteries because of high lithium ion conductivities. The sulfide electrolyte powders pressed at ambient temperature have much lower grain boundary resistance compared to oxide electrolytes. The all-solid-state batteries using Li2S-P2S5 solid electrolytes have thus good interfaces between solid electrodes and solid electrolytes because of a favorable formability of sulfide electrolytes [1]. On the other hand, a high capacity of the batteries was retained during charging and discharging for hundreds of cycles [2]. This would be due to the fact that sulfide solid electrolytes maintain electrode/electrolyte contacts against volume change of electrode materials during Li insertion/extraction. Consequently, these facts indicate the superiority of sulfide solid electrolytes in terms of mechanical properties. However, their mechanical properties have rarely been reported because such compounds are generally unstable in air. Recently, our group has succeeded in evaluating the elastic modulus of Li2S-P2S5 sulfide electrolytes [3]. The Young’s moduli of Li2S-P2S5 glasses are about 18-25 GPa and these moduli are lower than those of oxide solid electrolytes such as cubic Li7La3Zr2O12, which is reported as 149.8 ±0.4 GPa at a relative density of ~97% [4].Various properties such as stability or conductivity of Li2S-P2S5 glasses are changed by adding a third component to Li2S-P2S5 glasses. We reported that the addition of oxides as a third component to Li2S-P2S5 sulfide glasses improved the electrochemical stability and chemical stability in air [5,6]. On the other hand, lithium-ion conductivities of Li2S-P2S5 sulfide glasses are increased by adding LiI [7]. These sulfide glasses are thus attractive electrolytes to apply for all-solid-state batteries because of the superior stability or conductivity. However, their mechanical properties have not been investigated.In this study, (70-x)Li2S·xLi2O·30P2S5 (x=0, 10, 20 mol%), 70Li2S·(30-y)P2S5·yP2O5 (y=0, 3, 10 mol%) and (100-z)(0.75Li2S·0.25P2S5)·zLiI (z=0, 5, 10, 20, 30 mol%) sulfide glass electrolytes were prepared by mechanical milling. The formability of the glass powders was investigated by powder compression tests. A partial substitution of oxides for sulfides lowered the formability of glasses, while the addition of LiI to sulfides improved the formability. Furthermore, Young’s moduli of these glasses were evaluated by ultrasonic wave velocity measurements. The Young’s moduli increased with an increase in the P2O5 content, while those decreased with an increase in the LiI content.

Effect of Delamination on the Strength of Laminated Glass Plate Structures

Laminated glass which consists of two glass sheets connected to each other with PVB interlayer is used in many engineering applications for years. Despite the long history of the use of laminated glass in buildings there are serious problems about delamination of laminated glass units. This paper provides information about delamination issues of laminated glass plate structures. Delamination of laminated glass unit may be due to the thinning of PVB (Polyvinyl Butyral) interlayer or the folds which occur during the manufacturing process. Laminated glass behaves in a complex manner due to the effect of geometry that undergoes large deflection even under their own weight and the order difference between the elastic modulus of glass and interlayer. Because of the mentioned reasons large deflection analysis has to be performed in the determination of the effect of delamination on the strength of laminated glasses.

Maxwell equation and classical theories of glass transition as a basis for direct calculation of viscosity at glass transition temperture

The main relaxation theories of glass transition (Leontovich-Mandelstam and Volkenstein-Ptitsyn) variously formulate the kinetic criteria of glass transition. Both of the approaches are shown to be equivalent in physical sense and provide a single expression that connects the rate of change of a melt temperature and the structure relaxtion time. The theory characterizes the width of a temperature band δTg in which the glass transition occurs. The values of δTg can either be obtained from the experiment or be accepted to conform to the value of a temperature step under the change of viscosity by an order of magnitude (direct method for finding by the Volkenstein-Ptitsyn theory). Using the Maxwell equation, a new equation for the calculation of the viscosity for viscoelastic relaxation was suggested, which is based on a shear modulus of glass and the cooling rate. The theory was verified basing on the published data for oxide glass. The average difference between the calculated and measured values of lgη upon glass transition comprises 0 ± 0.30. These results correspond to the cooling rate of 3 K/min and log(η, Pa s) = 12.76 ± 0.26 (for all glass considered). It is shown that the most probable cooling rate which provides the viscosity upon glass transition of ∼1012 Pa s is close to 20 K/min (oxide melts). The theory predetermines the dependence of viscosity upon glass transition on the nature of a glass-forming liquid. The disadvantages of other approaches to the problem under consideration are demonstrated.

On the mechanical properties of lead borate glass

The mechanical properties of lead borate glasses were investigated using ultrasonic wave velocity measurement and nanoindentation. Creep tests at room temperature were performed by holding the indenter at peak load for extended time. Both Young's modulus and nanohardness decreased with increasing PbO molar fraction from 0.35 to 0.75. Creep decreased by increasing PbO from 0.35 to 0.50 mole fraction, and remained relatively unchanged at greater lead concentrations. The variation of Young's modulus with composition was attributed primarily to that of boron coordination number, whereas the variation of creep was attributed to the evolution of lead from glass modifier to former with the increase of lead concentration. Furthermore, the Young's moduli of glasses were predicted using Makishima–Mackenzie model. By considering the effect of cations' coordination numbers on the properties of oxides, marked improvement in the predictions of Young's modulus were made over previous such estimations.

Mechanical properties of glasses and TiO2 nanocrystal glass composites in BaO–TiO2–B2O3 system

Glasses and glass-nanocrystal (anatase TiO2) composites in BaO–TiO2–B2O3 system were fabricated by conventional melt-quenching technique and controlled heat treatment respectively. Poisson's ratio and Young's moduli were predicted through Makishima–Mackenzie theoretical equation for the as-quenched glasses by taking the four and three coordinated borons into account. Mechanical properties of the glasses and glass-nanocrystal composites were investigated in detail through nanoindentation and microindentation studies. Predicted Young's moduli of glasses were found to be in reasonable agreement with nanoindentation measurements. Hardness and Young's modulus were enhanced with increasing volume fraction of nanocrystallites of TiO2 in glass matrix whereas fracture toughness was found susceptible to the surface features. The results were correlated to the structural units and nanocrystals present in the glasses.

Determination of the susceptibility of the shear modulus to the defect concentration in a metallic glass

The susceptibility of the shear modulus to the concentration of interstitialcy-like defects in a metallic glass has been determined using calorimetric data and in situ measurements of the shear modulus of glass and parent crystal at different heating rates. The obtained results provide further support for the Interstitialcy theory, which consistently connects equilibrium/supercooled liquid, glassy and crystalline states.