Density of glasses

What will be the terminal falling velocity of a glass sphere 1 mm in diameter in water if the density of glass is 2500 kg/m3 ... 

The true density of glass (density in vacuo) (d ) is calcd from the equation... 

Resnik has shown91 that an effective way of reducing the apparent density of a syntactic foam is to decrease the apparent and bulk densities of the filler. Reducing the apparent density of glass microspheres from 450 to 350 kg/m3 reduces the apparent density of the syntactic foam from 707 to 630 kg/m3, the binder concentration remaining the same. 

ASTM C729-75 el (1995), Standard Test Method for Density of Glass by the Sink-Float Comparator, American Society for Testing and Materials, Philadelphia, PA. 

The density of glasses decreases with increasing temperature thermal expansion curves indicate that above the expansion coefficient increases and the density therefore decreases at a higher rate than below T. In Fig. 46 this is illustrated for the densily of SiO (Bacon at a ., 1960) and B2O3 (Li et ah, 1960). 

While the densities of crystalline materials are not particularly sensitive to the thermal history of the sample, densities of glasses are always dependent upon the thermal history of the particular sample measured. Although the differences in density which result from changes in thermal history are not particularly large, they can be very important in certain applications, especially those requiring highly reproducible values of the refractive index of glasses. 

Figure 7.5 Effect of time on the density of glasses for temperatures in the glass transformation region...

Estimate the hindered settling velocity of a 25% (by volume) suspension of 200pm glass beads in an inelastic carboxymethyl cellulose solution (n = 0.8 and m = 2.5Pa S") in a 25 mm diameter tube. The density of glass beads and of the polymer solution are 2500 kg/m and 1020kg/m respectively. 

Natural fibres show many advantages over glass fibres when used as reinforcement of synthetic polymers (see Table 5.1) the relatively high density of glass fibres 2.5 g/cm ) compared to cellulose or ligno-cellulose fibres of 1.5 g/cm makes lightweight applications possible. 

Two vertical cylindrical glass rods 1 cm in diameter with well polished flat ends are held togethet by a 150-nm-thick layer of water between the two ends. If the water meniscus is semicircular all around the cylinder circumference, what length can the lower cyhnder have before it is detached by gravity from the upper one Assume the density of glass to be 2.5 g cm. ... 

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