Structural glass

Material properties can be further classified into fundamental properties and derived properties. Fundamental properties are a direct consequence of the molecular structure, such as van der Waals volume, cohesive energy, and heat capacity. Derived properties are not readily identified with a certain aspect of molecular structure. Glass transition temperature, density, solubility, and bulk modulus would be considered derived properties. The way in which fundamental properties are obtained from a simulation is often readily apparent. The way in which derived properties are computed is often an empirically determined combination of fundamental properties. Such empirical methods can give more erratic results, reliable for one class of compounds but not for another. 

Overview of the Classical Theory of the Structural Glass Transition The Intrinsic Excitations of Amorphous Solids... 

II. OVERVIEW OF THE CLASSICAL THEORY OF THE STRUCTURAL GLASS TRANSITION... 

Monomers Molecular structure Glass transition Order-crystallinity Type of material Solubility Effect of T°... 

The defining property of a structural glass transition is an increase of the structural relaxation time by more than 14 orders in magnitude without the development of any long-range ordered structure.1 Both the static structure and the relaxation behavior of the static structure can be accessed by scattering experiments and they can be calculated from simulations. The collective structure factor of a polymer melt, where one sums over all scattering centers M in the system... 

J. Zinn-Justin, Eds., North-Holland, Amsterdam, 1990, pp. 287-503. Aspects of Structural Glass Transitions. 

Numerical Simulation of Structural Glasses Comparing Parallel Tempering and Conventional Molecular Dynamics. 

Indirect evidence of nonequilibrium flucmations due to CRRs in structural glasses has been obtained in Nyquist noise experiments by Ciliberto and co-workers. In these experiments a polycarbonate glass is placed inside the plates of a condenser and quenched at temperatures below the glass transition temperature. Voltage fluctuations are then recorded as a function of time during the relaxation process and the effective temperature is measured ... 

Through-holes are only possible in very thin substrates. This process can be combined with other means of structuring glass for example, microsandblasting or ultrasonic lapping (Figure 2.14). 

Four features of a polymer solute figure prominently in the polysaccharide-water interactions, viz., bonding, branching, ionization, and nonuniformity of the repeating structure (Glass, 1986). 

In the present example polydimethylsiloxane (PDMS) is deposited from an iso-propanol solution onto a glass surface [49], Due to the small amount of PDMS deposited by this technique, with optical microscopy the sample surface appears structureless. For the optical micrograph shown in Fig. 10b we selected a position which exhibits small dust particles by purpose, to demonstrate that the surface was focused. By optical microscopy the untreated and the nano-structured glass surface are indistinguishable. 

High performance (rj > 7%) a-Si H solar cells have been fabricated in three different structures as shown in Figs. 6 and 7. The highest-perform-ance devices ( / = 10.1%) have been fabricated in the structure glass/Sn02/ p-i-n/Ag, in which the p layer is an alloy of a-Si C H (Catalano et al., 1982). The p layer typically contains about 20-30 at. % carbon (Morimoto... 

The I- V characteristic shown in Fig. 8 is for a cell with the structure glass/Sn02/p-i-n/Ag, where thep layer is alloyed with carbon (Catalano et al., 1982). The conversion efficiency was 10.1% with Vx = 0.84 V, JK = 17.8 mA cm-2, and FF = 0.676. The spectral response (or external quantum efficiency) of the same 10.1% cell is shown in Fig. 9. An integration of the quantum efficiency with the AM 1 solar spectrum gave a current density of 17.6 mA cm-2, in good agreement with the measured value of JK (Catalano et al., 1982). 

It is clear that Tgxp is a function of curing conversion or molecular weight (for linear polymers) at adiff. One can observe a noticeable difference between T xp and T for such processes of polymer synthesis as polyaddition or condensation polymerization reactions. It is especially important for polymers with high T . For many heat-resistant polymers, T is higher than the temperature limit of their chemical decomposition. We can never reach natural T for these polymers. For such polymers, one really measures only Tgxp, the value of which depends on the reaction conditions. For structure-glass transition temperature correlations of networks, T is the most important quantity. 

Permeation and dissolution are the main processes determined by diffusive mass transfer. Permeation of polymers by small molecules depends on their solubility and diffusivity. For both quantities reasonable estimations are possible if some basic data of the permeating molecules (e.g. critical temperature and collision diameter) and of the polymer (structure, glass transition temperature, crystallinity) are known. For the estimation of the permeability of thin layers (films) an additive quantity, the permachor, is available. 

T. S. Grigera and N. E. Israeloff, Observation of fluctuation-dissipation theorem violations in a structural glass. Phys. Rev. Lett. 83, 5038 (1999). 

Metis161 reported a preliminary cost study on a 500-L scaled-up modular photobioreactor, and outlined the following cost distribution for the unit based on operating it for a period of 6 months photobioreactor materials, 45% mineral nutrients, 39% labor 4% water supply, 4% land lease, 2% power, 1% and miscellaneous expenses, 5%. He reported the actual cost of the materials for the pilot photobioreactor unit as 0.75 m 2, but the material used and the lifetime of the unit was not stated. This cost is much lower that the often quoted estimates of up to 100 per meter square using glass covered structures. Glass does not appear to be a realistic material to use in a commercial photobioreactor system because of both initial and replacement costs. 

Structural glass-reinforced plastic based on aminoplasts is being used in aircraft construction, machine- and ship-building in electrical and radio engineering (switchgear, switchboards, panels). 

Shalaev, E.Y. Eranks, E. Structural glass transitions and thermophysical processes in amorphous carbohydrates and their supersaturated solutions. J. Chem. Soc. Earaday Trans. 1995, 91, 1511-1517. 

For airports, stadiums, and other structures, glass fiber fabric coated with PTFE is fabricated into roofing and enclosures, where it provides excellent resistance to weathering, including exposure to UV rays in sunlight, flame resistance for safety, and low surface energy for soil resistance and easy cleaning. 

Early work attempted to draw a close analogy between the dye-sensitised cell and the ETA cell. Much of the experimental work therefore focused on nanoporous TiOa as the substrate material. For the deposition of a CulnSi absorber layer into the nanoporous network, several methods such as electrodeposition, spray pyrolysis and atomic layer deposition have been explored. Our own efforts have concentrated on combining the ILGAR technique and electrodeposition to prepare the structure glass/SnOi/nanoporous TiOa/CulnSi/ CuSCN/Au. Krunks et al. (1999, 2001) and Wienke et al. (2003) successfully used solution chemistry and spray pyrolysis to deposit CuInSi absorbers on TiOz, and Nanu et al. (2003, 2004) have applied atomic layer deposition for FeSz and CulnSz deposition in nanoporous TiOz. 

A special-purpose photo-structured glass called FOTURAN (available from Mik-roglas Chemtech GmbH - www.mikroglas.com), which is based on lithium aluminum silicate and is especially useful for creating microchannels and related structures with high aspect ratios. 

The supercooled liquids of ethanol and propanol were investigated starting either by cooling the normal liquid or melting the structural glass, while supercooled liquid methanol was prepared by melting the structural glass. 

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