Glass spheres, viscosity

Several studies have considered the influence of filler type, size, concentration and geometry on shear yielding in highly loaded polymer melts. For example, the dynamic viscosity of polyethylene containing glass spheres, barium sulfate and calcium carbonate of various particle sizes was reported by Kambe and Takano [46]. Viscosity at very low frequencies was found to be sensitive to the network structure formed by the particles, and increased with filler concentration and decreasing particle size. However, the effects observed were dependent on the nature of the filler and its interaction with the polymer melt. 

FIG. 4.9 Experimental verification of Einstein s law of viscosity for spherical particles of several different sizes (Squares are yeast particles, Rs = 2.5 71m circles are fungus spores, Rs = 4.0 /xm triangles are glass spheres, R, = 80 /xm). Open symbols represent measurements in concentric-cylinder viscometers, and closed symbols represent measurements in capillary viscometers. (Data from F. Eirich, M. Bunzl, and H. Margaretha, Kolloid Z., 74, 276 (1936).)... 

Figure 4.10 shows the viscosity of dispersions of glass spheres of radius 65 ixm plotted in the manner suggested by Equation (43). Several conclusions are evident from the data replotted in this way ... 

Fig. 9. Shear viscosity ratio of PDMS suspensions of silane-treated glass spheres (ca. 10 mm in diameter) to that of identical bare glass spheres at the same volume fraction ( )=0.28> measured at T=25 °C in steady state for three PDMS molecular weights, reproduced from [48]...

Fig. 4.9 Effect of particle asperity on the relative viscosity of molten polymer suspensions. Particles studied were as follows , glass spheres , natural calcium carbonate A, precipitated calcium carbonate o, glass fibers—aspect ratio = 18 ...

Figure 13.31 Influence of the volume fraction of glass spheres dispersed in a thermoplastic polymer at 150°C on the viscosity. (From Ref. 56.)...

For both mechanisms the effect of temperature on deposition can be attributed to change in viscosity, as surface tension does not vary much with temperature. Investigation of the effect of viscosity with ash particles is difficult, because little is known about the viscosities of iron aluminosilicates and ferrous sulfide at temperatures from 850° to 1050°C and, in any case, the ash particles vary in composition and presence of high melting phases. Therefore, we have chosen to use glass spheres as a homogeneous model material of known viscosity in tests for a study of deposition. We assume that the two materials are sufficiently alike in relevant properties that their borderlines for deposition occur at the same viscosity although their temperatures there may be different. We report here a few results of a preliminary nature. 

We have chemically analyzed the glass spheres and from this estimated the viscosity at 800 and 850 C by means of the correlation equations of Lyon ( ) The range of viscosity thus obtained over the above temperature range is 6.3 X 10 to 2.9 X 10 poises. This is near the geometric mean of the viscosities at the softening and working temperatures of soda-lime glass ( ). 

Glass sphere Spheres, in addition, called beads, are uses as fillers and reinforcements. They are available in different forms and a wide range of dimensions (5 to 1000 p.m). Their smooth shapes reduce abrasive and viscosity effects. 

For pure fluids (e.g. water, glycerine, ethyl alcohol, acetic acid) Bloembergen et al. [1] found theoretically and experimentally a correlation between the NMR relaxation times T and 72 > respectively, and the dynamic viscosity ii of Newtonian fluids, which is valid independently of temperature and pressure. Harz [3] could show that this correlation also holds for aqueous solutions like treacles, fruit juices, beer and wine. Further studies on silicone oil/glass sphere suspensions and beer mashes demonstrated that the 72-11 correlation, which originally was exclusively derived for Newtonian fluids, can also be applied to suspensions [4]. In contrast to solutions, the dependence is nonpotential. 

The flow behavior of silicone oils [5] and silicone oil/glass sphere suspensions [14] was studied by several authors. One of the most used rheological material parameters to characterize the flow behavior is the zero-shear-rate viscosity tIq. The t]o value of the linear silicone oils studied are correlated with the relevant weight-average molecular weight Af by Eq. 3 [16], where a = 3.58. 

Low-density hollow glass spheres are primarily used in polymers whose processing does not involve high viscosities and high pressures. Polymers filled with hollow glass spheres contain entrapped gas, which makes them comparable to foams. In fact, they are called syntactic foams. Besides density gains, stiffness as well as thermal and acoustical insulation can be significantly improved. 

Small amounts of inorganic fillers such as fumed silica, high surface area alumina, bentonites, glass spheres and ceramics are mixed with polyols such as propylene glycol to increase viscosity for printed electrodes. Proposed printed electrodes are carbon black, graphite, metallic or plated metaUic particles. 

The ratio of sedimentation velocity to free-falling particle velocity is (1 - C), where C is the fractional volume concentration. For a system of 0.1-mm-diameter glass spheres (density 2600 kg/m ) settling in water (density of 1000 kg/m, viscosity of 1 mNsec/m ) find the concentration at which the rate of deposition of particles per unit area will be a maximum. 

Figure 6.4 Variation of relative viscosity at constant shear stress as a function of the shear stress for a suspension of 15 pm diameter glass spheres in a thermoplastic polymer. (Reprinted from Ref. 95 with kind permission from Elsevier Science-NL. Sara Burgerhartstraat 25,1055 KV Amsterdam, The Netherlands.)...

Various bimodal mixtures were compounded into a polybutene grade 24 polymer obtained from the Petrochemical Division of the Chevron Company, at total solids concentrations up to 60% by volume. The polybutene pol)rmer was a Newtonian liquid at room temperature whose viscosity and density at 22°C were 25 Pa sec and 898kg/m, respectively. Due to the relatively high viscosity of ti e polybutene, it was found that the glass spheres suspended in the polymer remained dispersed for at least 24 h before complete settling occurred. 

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