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Modelling glasses

No single method can predict all crystal structures and many crystal structures cannot be predicted by any technique currently available. Structure modelling [Pg.162]


Figure 1 Amplitude distribution of AE signals from model glass epoxy specimens... Figure 1 Amplitude distribution of AE signals from model glass epoxy specimens...
Vitreous siUca is considered the model glass-forming material and as a result has been the subject of a large number of x-ray, neutron, and electron diffraction studies (12—16). These iavestigations provide a detailed picture of the short-range stmcture ia vitreous siUca, but questioas about the longer-range stmcture remain. [Pg.497]

E. Sciortino and P. Tartaglia, Extension of the fluctuation-dissipation theorem to the physical aging of a model glass-forming liquid. Phys. Rev. Lett. 86, 107-110 (2001). [Pg.122]

The origin of this absorption may be water molecules with one OH group bonded to the membrane and the second OH group non-H-bonded or water molecules with H-bonds to weak acceptors of the membranes. In both cases the water transport through these membranes may be related to weak H-bonds water-membrane. In addition the spectroscopic observations show in celluloseacetate — or polyimide — membranes are less water molecules of the type of liquid water. In agreement with this observation we have found in model glass membranes with low salt rejection (about 70%) at high relative humidity water spectra not far from the spectra of liquid water. As result of these first experiments we may discuss two possible mechanism of membranes for desalination processes ... [Pg.172]

Very recently, much progress has been made using powerful computer simulations, which can realistically model glass formation in simple liquids such as argon, or can model less realistically the formation of glassy characteristics in more complex liquids such as polymers. No doubt these methods will continue to enhance our understanding of glassy behavior. ... [Pg.229]

One important point we should stress, in conjunction with our current interest, is that similar slow relaxation as liquid water is observed in much simpler model systems The binary mixture of Lennard-Jones liquids, which consist of two species of particles, is now studied extensively as a toy model of glass-forming liquids. It is simulated after careful preparation of simulation conditions to avoid crystallization. Also, the modified Lennard-Jones model glass, in which a many-body interaction potential is added to the standard pairwise Lennard-Jones potential, is also studied as a model system satisfying desired features. [Pg.392]

Buchner, S., and Heuer, A., Potential energy landscape of a model glass former Thermodynamics, anharmonicities, and finite size effects. Phys. Rev. E 60, 6507 (1999). [Pg.76]

Tolle, A. (2001) Neutron scattering studies of the model glass former ortho-terphenyl. Rep. Prog. Phys. 64, 1473... [Pg.62]

A fundamental property that determines the state of a reacting system is its extent of cure or chemical conversion (a). Several papers have shown that there is a unique relationship between the glass-transition temperature (Tg) and a that is independent of cure temperature and thermal history. This may imply that molecular structures of materials cured with different histories are the same or that the changes in molecular structure do not affect Tg. There are generally accepted to be two approaches to modelling glass-transition-conversion relationships, namely thermodynamic and viscoelastic approaches. These are summarized in Table 3.8. [Pg.286]

Within the framework of the cluster model glass transition is considered as thermo-fluctuational clusters formation at temperature [HO]. Besides, the fractal conceptions are interconnected with the cluster model and these models main characteristics relationship is given as follows [107] ... [Pg.119]

T. B. Schroder, S. Sastry, J. C. Dyre, and S. C. Glotzer, Crossover to potential energy landscape dominated dynamics in a model glass-forming liquid. J. Chem. Phys., 112 (2000), 9834. [Pg.62]

Preparing glasses for glass-ionomer cements was guided by the Random Network concept of Zacheriasen [30]. This concept models glasses as random assemblies of SiO tetrahedra linked at their comers to form chains. The main mles of the Random Network concept are as follows ... [Pg.111]

An alternative method was introduced using a hybrid model. In the hybrid model, a FLUENT sub-model was used to model glass flow and thermal conditions with plimger motion from the entrance of the glass tank to the orifice outlet. The transient temperature and velocity at the FLUENT/POLYFLOW interface are then mapped to a POLYFLOW sub-model as time-dependent boimdary conditions. The glass gob free surface deformation process was modeled in the POLYFLOW sub-model. [Pg.197]


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