Fragile glass

Figure 2 Sketch of typical temperature dependencies of the viscosity r of glass-forming systems. The viscosimetric Tg of a material is defined by the viscosity reaching 1013 Poise. Strong glass formers show an Arrhenius temperature dependence, whereas fragile glass formers follow reasonably well a Vogel-Fulcher (VF) law predicting a diverging viscosity at some temperature T0.

The pH electrode consists of a closed-end glass tube that has a very thin fragile glass membrane... 

An alternative to the use of small spherical phials, which often has advantages in terms of the flexibility of the apparatus, is the use of calibrated vessels or ampoules with break-seals. They consist usually of a tube 3-6 mm i.d. and 20-70 mm long with a calibration mark and carrying a fragile glass membrane which can be broken when desired, so as to admit the contents of the ampoule to a mixing vessel or reaction vessel. The construction of different types of magnetic break-seals has been described in Section 2.2.4.4. 

By their nature, gravimetric apparatus are quite fragile and care must be exercised in their use. Volumetric equipment usually contains fragile glass components. Continuous flow instruments are all metal, except for the sample cell, and are the least fragile of the various apparatus. 

Borosilicate glass and ceramics are inert materials and have great chemical stability the weak point about glass, however, is its fragility. Glass can be used for both organics and inorganics, but one should be mindful of the fact that it is a potential source of boron and silicon and cannot be used if these elements are to be determined. 

An intimate connects exists between the shape of the relaxation function and steepness index [3,5,48,89,116,117], Strong liquids have less broad relaxation functions compared with fragile glass formers. The degree of nonexponentiality is reflected in the Kohlrausch exponent [1... 

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