Glasses characterisation

Crisp, S., Lewis, B. G. Wilson, A. D. (1976). Characterisation of glass-ionomer cements. 1. Long term hardness and compressive strength. Journal of Dentistry, 4, 162-6. 

DE-MS was employed in the characterisation of resinous materials from Roman ceramic vessels, Palaeolithic stone tools, Roman glass unguentaria and amphorae [14,16,18,23]. 

That particular combination of properties possessed by high polymers, characterising the rubber-like state. Depending on the temperature and the time of stressing, a high polymer may show viscous flow or high elasticity. See Elasticity, Glass Transition, Thixotropy and Viscosity. 

The conventional approach to solvent extraction is the batch method. Early work with this method was hampered by the low concentration of the compounds present and the relative insensitivity of the methods of characterization. Thus lipids and hydrocarbons have been separated from seawater by extraction with petroleum ether and ethyl acetate. The fractionation techniques include column and thin-layer chromatography with final characterisation by thin-layer chromatography, infrared, and ultra-violet spectroscopy and gas chromatography. Of these techniques, only gas chromatography is really useful at levels of organic matter present in seawater. With techniques available today such as glass capillary gas chromatography and mass spectrometry, much more information could be extracted from such samples [20]. 

A method of characterising transport mechanisms in solid ionic conductors has been proposed which involves a comparison of a structural relaxation time, t, and a conductivity relaxation time, t . This differentiates between the amorphous glass electrolyte and the amorphous polymer electrolyte, the latter being a very poor conductor below the 7. A decoupling index has been defined where... 

Since the glass-rubber transition is characterised by large chain parts becoming mobile (e.g. 50 monomer units), we can from a single Tg only conclude that the blend is homogeneous on that scale at a smaller scale (of a few links) a two-phase system may still be present. 

Much of what needs to be done about the techniques of removing water from glass apparatus and from solvents and reagents has been set out above in a more general context. It remains to point out a few pecularities which characterise the drying process rather than any other purification procedure and to discuss some drying agents. 

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