Melt, generally viscosity

In a number of works (e.g. [339-341]) the authors sought to superimpose graphically the flow curves of filled melts and polymer solutions with different filler concentrations however, it was only possible to do so at high shear stresses (rates). More often than not it was impossible to obtain a generalized viscosity characteristic at low shear rates, the obvious reason being the structurization of the system. 

Hui H. and Zhang Y. (2007) Toward a general viscosity equation for natural anhydrous and hydrous silicate melts. Geochim. Cosmochim. Acta 71, 403-416. 

Ethylene-copolymer melts generally have a vinyl acetate proportion of approx. 5 to 35% by weight, equivalent to a melt index of Ml216/i9o°c=2 to 500 g/10 min. The melt temperatures in the low-pressure trap range from 160 to 200 °C, depending on the viscosity of the melt. Depending on the polymerization and on the pressure in the low-pressure trap, the melt contains free vinyl acetate (approx. 4000 ppm) in addition to the known ethylene content of... 

The major differences between solvent-based and hot-melt pressure-sensitive adhesives is that with hot melts the viscosity can no longer be controlled with solvents, and must, instead, be controlled either by temperature or by formulating. A further limitation is that waxes cannot, in general, be used for reducing viscosity as is the case with conventional hot melts, as waxes tend to reduce tack drastically. Hence the major influence on viscosity in the formulation must come from the choice and quantity of tackifier resin. 

It is generally known that melt shear viscosity is a material property useful for evaluating melt processability of the material in traditional thermoplastic processes such as injection molding or extrusion. For conventional fiber spinning thermoplastics such as... 

The addition of fluoride ions to phosphate melts generally reduces their viscosity. This is believed to be due to the breaking of P-O-P linkages as a result of formation of P-F terminal linkages (12.64a) [21],... 

The viscosity of a polymer melt generally reduces with increased amounts of volatile component. Figure 5.4 shows the viscosity of polystyrene as a function of the solvent concentration. In this example the solvent is ethylbenzene [28]. 

The viscosity of a polymer melt generally depends on M via a power law. Under the reasonable assumption that addition of small amounts of a plasticizing solvent does not immediately change the qualitative nature of the polymer dynamics, it follows that Eiq. 12.4 should be expected to describe (c, M) under near-melt conditions, at least insofar as the M-dependence is concerned. If at lower polymer... 

It is worth noting that above Tg, supercooled inorganic compound glass melts generally exhibit Newtonian viscosity (see Section 10.5.4). In the 7 region itself they are viscoelastic supercooled liquids, transforming below 7 to glasses which commonly behave elastically up to fracture under normal loads. 

Melt Viscosity. Viscosities of resins at standard temperatures yield information about molecular weight and molecular weight distribution, as weU as valuable information with respect to appHcation logistics. Some customers prefer to receive resins in molten form. Melt viscosities help to determine the required temperature for a resin to be pumpable. Temperature—viscosity profiles are routinely suppHed to customers by resin manufacturers. In general, a molten viscosity of 1—1.1 Pa-s (1000—1100 cP) or less at process temperatures is convenient for the pumping and handling of molten resin. 

Liquid metal selection is usually limited to the lower melting point metals in Table 15. Figure 17 shows that Hquid metal viscosity generally is similar to water at room temperature and approaches the viscosities of gases at high temperature. Hydrodynamic load capacity with both Hquid metals and water in a bearing is about 1/10 of that with oil, as indicated in Table 2. 

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