Fracture mechanics characterization of mixed-mode toughness of thermoplast/glass interfaces (brittle/ductile interfacial mixed-mode fracture)

Interfacial toughness is enhanced when the mode-mixity of the biaxial near-tip stress state approaches mode II. Conversely, when the near-tip mode-mixity is close to pure mode I, the interfacial toughness curve exhibits a minimum. This toughness minimum is believed to represent the so-called intrinsic adhesion. Within linear elasticity, the biaxial, singular near-tip solution for an open interface crack may be employed for characterizing the local stress state as long as non-linearities due to crack-wall contact and plastic flow are contained within a length scale small enough compared to the extension of the near-tip opening-dominated fields. In the present work, the interfacial mixed-mode fracture toughness curve was determined for a polyethylene/glass compound. Subsequent to the reduction of experimental data based on the linear-elastic crack model, the applicability of linearelastic fracture mechanics is verified by comparing the estimated extension of the plastic zones to the extension of the K-dominance zone. It is found that within the mixed-mode range accessible to linear-elastic fracture mechanics the apparent interfacial fracture toughness varies by about an order of magnitude.     

The influence of water on the structure and glass transition of sodium borate supercooled liquids from the small-angle X-ray scattering data

Sodium borate glasses containing 5.5, 15, and 25 mol % Na₂O are synthesized under different conditions (different temperatures and times of heat treatment, treatment under vacuum) and studied by the small-angle X-ray scattering (SAXS) technique. The temperatures of the glass transition and the transition from the supercooled liquid state to the noncrystalline solid state are determined from the temperature dependences of the SAXS intensity. It is revealed that a decrease in the water content leads to an increase in the glass transition temperatures and to an increase in the SAXS intensity in the case of glasses containing 15 and 25 mol %. It is assumed that this behavior can be associated with the increase in the isothermal compressibility.     

Inhomogeneity on the nanometer scale as a universal property of glasses

The concept of inhomogeneity as a universal property inherent in all substances in the vitreous state is analyzed. The inferences made from the data obtained for the glass structure with the use of different structure-sensitive methods (X-ray and neutron scattering, low-frequency Raman scattering, etc.) and the results of the computer simulation of the glass structure are discussed. It is shown that the concept of inhomogeneous glass structure on the nanometer scale explains a large number of the physical properties of glasses.     

Inhomogeneity on the nanometer scale as a universal property of glasses

The concept of inhomogeneity as a universal property inherent in all substances in the vitreous state is analyzed. The inferences made from the data obtained for the glass structure with the use of different structure-sensitive methods (X-ray and neutron scattering, low-frequency Raman scattering, etc.) and the results of the computer simulation of the glass structure are discussed. It is shown that the concept of inhomogeneous glass structure on the nanometer scale explains a large number of the physical properties of glasses.     

Strength of display glass

The strength of dual-display glass surfaces 0.64 mm (Corning 1737 glass) and 0.70 mm (Eagle²⁰⁰⁰ glass) thick is measured in the initial state and after annealing. Large dispersion of the strength of the glass before and after annealing is found. It is suggested that the low values of the strength are caused by the adverse conditions of storing and handling glass samples.     

沙河玻璃现状调查及发展对策探讨

通过对河北省沙河市玻璃生产现状的调查,指出沙河市"小玻璃"必须在国家建设节约型社会、注重环境保护的大政策前提下,走平拉玻璃工艺与浮法玻璃工艺相结合的技术创新之路.     

钢化玻璃自爆机理的新发现——单质硅微粒引裂

通过对6块玻璃自爆残片的电镜观察和成分分析,发现并证明了引起钢化玻璃自爆的主要原因不仅仅是传统认识中的硫化镍(NiS)微粒,很多情况是由单质硅微粒引起的.进一步对单质硅微粒引起自爆的力学机理进行了分析和有限元模拟.结果显示:由于单质硅微粒周边玻璃的切向应力过大从而引起局部拉伸破坏并导致整体破裂,降温过程可以使这种应力增加并加大破裂危险.     

Expanded polytetrafluoroethylene as an auxetic material: effect of extension ratio on its structure and properties

The effect of extension ratio on the structure and property of expanded polytetrafluoroethylene (ePTFE) has been decisively studied. ePTFE is unique with its porous fibrillar network structure connected by nodes and also with its degree of orientation which increases with increases in extension ratio. It is found that the Poisson’s ratio of ePTFE is negative, and it is reduced dramatically with increased extension ratio. At the extension ratio of 30, the Poisson’s ratio reaches ? 10.00. By changes of extension ratio from 1 to 10, the segmental mobility of polymer chains becomes harder, and the dynamic glass transition temperature (T _g) is increased. Broad glass transition regions are revealed in tan δ versus temperature curves in polytetrafluoroethylene specimens stretched 20- (S20) and 30-fold (S30). As the extension ratio is increased, the thermal conductivity of the specimens is decreased. The thermal conductivity coefficient is dropped to 0.051 W m^?1 K owing to the appearance of more pores and low degree of crystallinity at higher extension ratio. The properties of ePTFE modified by carbonyl iron powder (CIP) have been investigated. CIP has affected the structure and properties of modified ePTFE. CIP-modified ePTFE also exhibits a negative Poisson’s ratio which is larger than ePTFE at the same extension ratio. The modified ePTFE reveals higher thermal conductivity coefficient than ePTFE itself.     

Suppression of Lanthanide Clustering in Glass by Network Topological Constraints

Here, we demonstrate the relationship between glass network topological structure and the chemical state of embedded lanthanide ions. It is revealed that a more dispersed state of lanthanide ions is shown in more constrained 3D rigid network, which delivers valuable information toward homogeneous doping in glasses from the perspective of glass topological structure. The results are believed to be of great significances in the development of advanced optoelectronic devices like high‐power laser, efficient fiber amplifier, smaller integrated photonic circuit, etc.     

Amorphous silica wastes for reusing in highly porous ceramics

The paper analyzes a solution in green manufacturing of foamed or cellular ceramics. The objective of this study was to determine the technical solution for rice husk ash and “tales” of mixed glass cullet reusing based on the specific properties of these materials for creation of spherical holes inside ceramic using the process of coalescence of cellular glass. The paper reports on experimental results obtained from the production of lightweight cellular glass granules produced using glass cullet and rice husk ash. Lightweight cellular glass granules were mixed with clay, pressed and fired in air at 920°C. Clay sintering and the formation of ceramic were followed with the coalescence of cellular structure of glass granules and with the formation of spherical hollows inside the matrix. Density and strength of the fired ceramic bodies were determined. It is observed that the lightweight ceramics with density 900 ÷ 920 kg/m³ possess a compressive strength of about 5 MPa that is acceptable for bricks or tiles manufacture. The utilization of amorphous silica waste for lightweight ceramics manufacture helps in reducing waste disposal concerns and costs associated, and also transforms the waste into an alternative raw material with added value, moreover making the final product cheap.     

Ultimate regimes of deformation of linear flexible chain fluid polymers

At temperatures far from the glass transition temperature linear flexible chain high polymers of narrow MMD when being deformed may undergo a transition from the fluid to the forced high elastic (and the glass) state. In simple shear, uniaxial extension and in the triaxial stressed state the transition of polymers to the forced high elastic state is accompanied by their rupture. Of decisive importance for this transition is the combination of the rate and amount of deformation. On the other hand, such a transition occurs at stresses which vary by 10–20 times for the various homologous series of linear flexible chain polymers. We have established unexpectedly simple relations connecting the parameters that characterize the rheological properties of polymers at deformation rates and stresses tending to zero with their ultimate strength and long term durability. This is determined by the fact that the polymers under consideration behave like linear bodies until they are fractured (in terms of the theory of linear viscoelasticity). From this it may be inferred that the selection of the simplest (as to composition) polymers having a highly homogeneous entanglement network plays a decisive role in the elucidation of the fundamental specificity of the rheological properties of polymeric systems.     

Determination of network density of composites containing inert fillers from stress—Strain measurements in the swollen state

Methods of estimating the concentration of effective network chains from the stress—strain behaviour of elastomers both dry and swollen in solvents are discussed. It is pointed out that while measurements in uniaxial extension are more difficult to carry out experimentally than measurements in uniaxial compression, they are preferred because they can provide more information about the behaviour of the elastomer. An equation is presented for relating the stress—strain behaviour of swollen composites containing inert fillers to the behaviour of a gum having the same degree of crosslinking; experimental data on SBR—glass bead composites are presented which indicate that the equation is applicable.     

Glass Formation and Physicochemical Properties of Alloys in the Cu–Te–I System

The glass formation and the physicochemical properties of alloys in the Cu–Te–I system are investigated. Consideration is given to the glass formation region in the Cu–Te–I system, the results of differential thermal and X-ray powder diffraction analyses, and the temperature dependence of the molar volume for melts. The phase diagram is constructed along the CuI–Te join passing throughout the glass formation region. The inference is drawn that the formation of the CuTeI and CuTe₂I chemical compounds favors extension of the glass formation region in the system under investigation.     

玻璃行业窑炉余热利用与烟气环保治理一体化的研究与应用

随着国家"十二五"对节能减排的深入推进,玻璃作为高耗能、高污染的行业被国家纳入控制范围中,受玻璃生产特点和烟气特点的制约,一直以来,如何将窑炉的节能与减排有效地结合起来,是一项有利于国家、有利于社会,也有利于企业健康发展的重要课题。本文重点结合玻璃生产实际案例进行分析,提出有效的解决办法。结果表明,将窑炉的余热利用发电、窑炉烟气的脱除NO、脱除SO、除尘一体化的方案是未来玻璃行业的必然选择。X2     

Microanalyses on the RuO2 Particle–Glass Matrix Interface in Thick-Film Resistors with Piezoresistive Effects

The piezoresistive mechanisms of composite thick films based on RuO₂ particles and both calcium-borosilicate and bismuth-borosilicate glass matrices were investigated by chemical and electrical microanalyses. The resistor based on bismuth-borosilicate glass showed higher sensitivity than that based on calcium-borosilicate glass. It was confirmed that the diffusion of ruthenium into glass affects the binding state of RuO₂ at the interface of the glass. Furthermore, an intermediate resistive layer is detected around the RuO₂ particle. These results suggest that the piezoresistive effect is related to a change in the electrical conductivity of the interfacial reaction layer caused by the diffusion of ruthenium into glass.     

Applications of a two-network model for crosslinks and trapped entanglements

The dependence of stress and birefringence on strain in uniaxial extension of crosslinked rubbers can accurately be described by a model in which the properties of a network of crosslinks and a network of trapped entanglements are additive. The crosslink network is neo-Hookean and the entanglement network can conveniently be described by the Mooney-Rivlin equation. When the crosslinks are introduced in a state of strain near the glass transition temperature, the two networks have different reference undeformed states; they can be distinguished by appropriate measurements in the state of ease where their associated stresses are equal and opposite and in the state of deformation where the cross-links were introduced and make no contribution to the stress. When partial relaxation is permitted before crosslinking, trapping probabilities can be calculated for both relaxed and unrelaxed entanglements and compared with the Langley theory. The results are consistent with the terminal mechanism of relaxation in the tube theory of Doi and Edwards.     

Formation of coloring complexes in glass colored with cerium and titanium oxides

The valence state of cerium and titanium ions in barium-strontium aluminosilicate glass with a different ratio of cerium and titanium oxides was investigated and the possible composition of the cerium-titanium complexes formed in silicate glass was analyzed. It was found that an active separate reaction between cerium and titanium oxides with the appearance of complex color centers takes place in synthesis of the glass. It is hypothesized that color centers primarily form between tetravalent cerium and tetravalent titanium in glass-forming melts.     

Mechanism of Formation of Redox Potential in Glass

It is demonstrated that the redox potential (ROP) of glass is formed depending on the type of gases released in heating batch materials. The ROP of glass has a significant effect on the valence state of iron and copper and the oxygen coordination number of Cu(II) ions.     

Amorphous state transitions in butadiene–acrylonitrile copolymers

Differential thermal analysis, creep measurements, and gas permeation rates are used to confirm the existence of a transition zone in three butadiene acrylonitrile copolymers in a temperature region that starts at roughly 15° to 25°C above the main glass transition temperatures of the copolymers and extends over a broad temperature range. The change appears to be slightly endothermic and softens the copolymers upon heating. It is speculated that the copolymers are in a mesomorphic state above their main glass temperature in which there is either a degree of ordering or a low-grade crystallinity of polybutadiene units along the copolymer chains. It is not until the copolymers are 50° to 75°C above their main glass temperature that they become truly amorphous.