Base glass phase separation

During heat treatment Zerodur base glass phase separates first, Fig. 2.24, and later small nuclei of about 5 nm in size precipitate. Fig. 2.25. If the temperature is not increased too rapidly, a large number of nuclei are formed before any crystal nucleation and growth of h-quartz s.s. is initiated. If this condition is observed during ceramization, then a high density of small h-quartz s.s. crystals can be obtained. Crystal densities for the h-quartz s.s. crystals are estimated to be about 10 cm, whereas the density of the nuclei is not known but may be even higher. 

Special gelation is based on phase separation within polymer solutions. If the separating phase exists as small, solid particles (crystal or glass), it may represent a cross-link of very high functionality. Even the typical semicrystalline polymer can be characterized as tightly cross-linked, nanophase-separated gels, as will be discussed... 

Kuraoka, K., Amakawa, R., Matsumoto, K., and Yazawa, T. (2000). Preparation of molecular-sieving glass hollow fiber membranes based on phase separation./ Membr Sci. 175 213-223. 

Direct evidence of nucleation during the induction period will also solve a recent argument within the field of polymer science as to whether the mechanism of the induction of polymers is related to the nucleation process or to the phase separation process (including spinodal decomposition). The latter was proposed by Imai et al. based on SAXS observation of so-called cold crystallization from the quenched glass (amorphous state) of polyethylene terephthalate) (PET) [19]. They supposed that the latter mechanism could be expanded to the usual melt crystallization, but there is no experimental support for the supposition. Our results will confirm that the nucleation mechanism is correct, in the case of melt crystallization. 

Not all colloid systems are stable. The most stable involve solid dispersion media, since movement through a solid host will be slow. Emulsions also tend to be stable think, for example, about a glass of milk, which is more likely to decompose than undergo the destructive process of phase separation. Aerosols are not very stable although a water-based polish generates a liquid-in-air colloid, the particles of liquid soon descend through the air to form a pool of liquid on the table top. Smoke and other solid-in-gas aerosols are never permanent owing to differences in density between air and the dispersed phase. 

Chromatographic Resolution. To optimize column-coating conditions and operating parameters glass capillary columns coated with various silicone-based stationary phases were tested with difficult-to-separate groups of PAH standards and Complex samples. The SE5 -coated columns performed excellently with respect to separation efficiency, column bleed and long-term stability. Other observers have had similar results with this... 

A phase separation technique, using solvent and subsequent swelling, has been described to separate PVC from polyester fabric, primarily to recycle the fabric (340,355). A technique for recycling PVC coated glass fibre fabric has been described, based on compression or injection moulding, with addition of an acid absorber (hydrotalcite) (49). 

Place 10 ml of urine in each of two 20-ml glass bottles fitted with plastic s ew-caps (McCartney bottles), and to one bottle add 1 to 2ml of M sulphuric acid and to the other add sufficient sodium bicarbonate to saturate the solution. Label the bottles A and B (acids and bases) respectively. Fill each bottle with a mixture of chloroform and isopropyl alcohol (9 1), screw on the caps, shake for 5 minutes, and centiifiige for 5 to 10 minutes. Aspirate the top aqueous phase using a Pasteur pipette connected to a water-operated vacuum pump, filter the chloroform extracts throu phase-separating paper to remove residual water, and collect the filtrates in 10-ml conical test-tubes ... 

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