Rheological flows

Rheology. Flow properties of latices are important during processing and in many latex appHcations such as dipped goods, paint, inks (qv), and fabric coatings. For dilute, nonionic latices, the relative latex viscosity is a power—law expansion of the particle volume fraction. The terms in the expansion account for flow around the particles and particle—particle interactions. For ionic latices, electrostatic contributions to the flow around the diffuse double layer and enhanced particle—particle interactions must be considered (92). A relative viscosity relationship for concentrated latices was first presented in 1972 (93). A review of empirical relative viscosity models is available (92). In practice, latex viscosity measurements are carried out with rotational viscometers (see Rpleologicalmeasurement). 

Dilatant Basically a material with the ability to increase the volume when its shape is changed. A rheological flow characteristic evidenced by an increase in viscosity with increasing rate of shear. The dilatant fluid, or inverted pseudoplastic, is one whose apparent viscosity increases simultaneously with increasing rate of shear for example, the act of stirring creates instantly an increase in resistance to stirring. 

Despite its attractive capabilities, the epifluorescence technique has some drawbacks. The fluorescent surfactant probe must not be miscible with the major phase of interest, and must not interact with the major phase in any way that changes the rheological flow or compression characteristics of the film. In addition, the probe itself must form a stable monolayer on the air-water interface. The area in which this work is to be performed must also be clean enough for accurate film balance work and must be free of vibration. 

Table 11.5 Rheological flow activation energies ( a) of PET, PTT and PBT melts [68]...

Natural and biomedical polymers Organometallic polymers Inorganic polymers Reactions of polymers Rheology (flow properties, viscoelasticity)... 

Line Activities. It is often necessary to make a quick check of the rheological flow properties of a specific sample in an in-process production line application. The equipment used may be either in-line flow apparatus or other simple characterization methods. 

G Mechanism of Detonation in Slurries Before proceeding with a discussion of the detonation mechanism of Slurries, we need to examine briefly the rheology (flow characteristics) of SE and SBA. Any Slurry, whether expl or not, by definition contains suspended solid particles in a continuous liq phase. This liq phase in SE or SBA may be 1) an unthickened AN (and other oxidizer or even sensitizer) soln 2) a thickened soln and 3) a thickened and cross-linked soln. The thickened and/or cross-linked liq phase is a gel. An analogy supplied by Cook (Ref 9, p 277) is that pure... 

For reviews and more information on the principles and practice of mineral-slurry pipelining see Refs. [90,615-618]. The relationships among suspension rheology, flow rate, and pressure drop in a pipeline are discussed in Section 6.7.1 and oil pipelining is discussed in Section 11.3.4. 

Figure 6.27 compares the experimental pressure profiles using plasticized thermoplastic resin (unfortunately, the rheological flow curve was not provided) with... 

Effects of polymer structure on rheology flow transitions processing... 

Vehicles that exhibit the unusual property of Bingham-type plastic rheological flow are characterized by the need to overcome a finite yield stress before flow is initiated. Permanent suspension of most pharmaceutical systems requires yield-stress values of at least 2-5 Pa (20-50 dyn/cm ). Bingham plastic flow is rarely produced by pharmaceutical gums and hydrophilic colloids. National Formulary (NF) carbomers exhibit a sufficiently high yield value at low solution concentration and low viscosity to produce permanent suspensions. The carbomers, however, require a pH value between 6 and 8 for maximum suspension performance. The polymer is essentially incompatible... 

The particle size distribution of a latex paint polymer determines its performance related to its film- forming properties, stability, rheology (flow), and morphology (form). The particles are usually spherical. Larger particles and a narrow distribution usually provide a more stabile system, because smaller particles with a wider distribution tend to interact and coagulate. SFFF is the most popular method to determine particle size distribution. 

Rheology Flow Curves. The rheological properties of cement slurries are important to many aspects of a cementing operation. They are obviously a key in the calculation of friction pressures, but they also play a role in the efficiency of the displacement process as well as on the thermal exchanges occurring during the placement. 

The formulation of coatings must be matched to the required property profile in terms of the resin/hardener system as well as the additives which influence the rheology, flow, deaeration, mechanical and chemical properties, resistance to yellowing and film colour. 

Damage tolerance of fibre reinforced thermoplastic composites Processing of polymer matrices using resin transfer moulding Fractal analysis of wear in short-fibre reinforced thermoplastic composites Rheology flow behavior of associative polymers in coating applications Kevlar-thermoplastic composites... 

The granule size distribution will be controlled by the suspension rheology (flow properties) and the process parameters (pump speed and air pressure). Normally, a certain size distribution width is achieved with an average size, typically around 100-200 pm. 

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