Temperature on viscosity, effect

Durand, A. 2007. Aqueous solutions of amphiphilic polysaccharides Concentration and temperature effect on viscosity. European Polymer Journal 43,1744-1753. 

Temperature coefficient, 205, 206, 335, 495, 506, 509, 511, 512 Temperature factor, 303 Temperature, effect on viscosity, 633 Tensile modulus of elasticity of composite materials, 329... 

Increasing the temperature due to radioactive heating decreases the viscosity of fluid. Within the zone of maximum temperature viscosity decreases up to four times in comparison with its reference value. This temperature effect on viscosity exists during all 300 years of simulation. 

Mathematical modeling of the flow through SSE considers that the screw and the barrel are unwound. The screw is stationary and the barrel moves over it at the correct gap height and the pitch angle. The initial models assumed (i) steady state, (ii) constant melt density and thermal conductivity, (iii) conductive heat only perpendicular to the barrel surface, (iv) laminar flow of Newtonian liquid without a wall slip, (v) no pressure gradient in the melt film, and (vi) temperature effect on viscosity was neglected. Later models introduced non-Newtonian and non-isothermal flows. Present computer programs make it possible to simulate the flow in three dimensions, 3D [39]. 

EFFECTS OF PROCESS VARIABLES 16.3.1 Temperature Effects on Viscosity... 

Whilst temperature rises at constant pressure cause a decrease in viscosity, pressure rises at constant temperature cause an increase in viscosity since this causes a decrease in free volume. It is in fact found that within the normal processing temperature range for a polymer it is possible to consider an increase in pressure as equivalent, in its effect on viscosity, to a decrease in temperature. 

Plastic Viscosity and Yield Point. Plastic viscosity and yield point measurements are obtained from a direct indicating viscometer. Due to the temperature effect on the flow properties of oil-base mud, the testing procedure is modified. The mud sample in the container is placed into a cup heater [23]. The heated viscometer cup provides flow property data under atmospheric pressure and bottomhole temperature. 

Molecular weight, temperature, and pressure have little effect on elasticity the main controlling factor is MWD. Practical elasticity phenomena often exhibit little concern for the actual values of the modulus and viscosity. Although MW and temperature influence the modulus only slightly, these parameters have a great effect on viscosity and thus can alter the balance of a process. 

The major mode of polyacrylamide decomposition at elevated temperature (in the absence of oxygen) is hydrolysis (319,320). Thus, the concentration of divalent metal ions has an effect on viscosity retention at high temperature. Chelating and sequestering agents have been used to reduce the adverse effect of... 

The viscosity of the polymer or mix also controls the level of the shear stresses developed in the nip region. The level of temperature in the rubber mass, by its effect on viscosity, will also influence the level of shear stresses developed. 

Diffusivities in liquids are comparatively low, a factor of 10 lower than in gases, so it is probable in most industrial examples that they are diffusion rate controlled. One consequence is that L-L. reactions are not as temperature sensitive as ordinary chemical reactions, although the effect of temperature rise on viscosity and droplet size sometimes can result in substantial rate increase. On the whole, in the presnt state of the art, the design of L-L reactors must depend on scale-up from laboratory or pilot plant work. 

The flames themselves can alter the turbulence. In simple open Bunsen flames whose tube Reynolds number indicates that the flow is in the turbulent regime, some results have shown that the temperature effects on the viscosity are such that the resulting flame structure is completely laminar. Similarly, for a completely laminar flow in which a simple wire is oscillated near the flame surface, a wrinkled flame can be obtained (Fig. 4.41). Certainly, this example is relevant to <5L < /k that is, a wrinkled flame. Nevertheless, most open flames... 

Because pi, mobility, and viscosity are all affected by temperature, the use of internal standards is recommended. However, the use of synthetic pi standards to estimate pis should be approached with caution because the pis of the protein sample and standards may not be affected equally by temperature. Temperature has a direct effect on viscosity and therefore all effects of viscosity on the CIEF process apply as temperature changes. 

In the mucosal environment, effects of salt, pH, temperature, and lipids need to be taken into consideration for possible effects on viscosity and solubility. A pH range of 4-7 and a relatively constant temperature of 37°C can generally be expected. Observed solution properties as a function of salt and polymer concentration can be referred to as saline compatibility. Polyelectrolyte solution behavior [27] is generally dominated by ionic interactions, such as with other materials of like charge (repulsive), opposite charge (attractive), solvent ionic character (dielectric), and dissolved ions (i.e., salt). In general, at a constant polymer concentration, an increase in the salt concentration decreases the viscosity, due to decreasing the hydrodynamic volume of the polymer at a critical salt concentration precipitation may occur. 

Selected entries from Methods in Enzymology [vol, page(s)] Theory, 63, 340-352 measurement, 63, 365 cryosolvent [catalytic effect, 63, 344-346 choice, 63, 341-343 dielectric constant, 63, 354 electrolyte solubility, 63, 355, 356 enzyme stability, 63, 344 pH measurements, 63, 357, 358 preparation, 63, 358-361 viscosity effects, 63, 358] intermediate detection, 63, 349, 350 mixing techniques, 63, 361, 362 rapid reaction techniques, 63, 367-369 temperature control, 63, 363-367 temperature effect on catalysis, 63, 348, 349 temperature effect on enzyme structure, 63, 348. 

Column stability, 161 Column temperature, 267 effect on retention, 192,200 effect on viscosity, 192 nonuniform temperature profile, 194 optimization of, 193 Column tubing, 145 cleaning of, 145 irmer surffice of, 145... 

The temperature dependence of viscosity of 23 room-temperature ionic liquids was investigated. The size and symmetry of the cations and anions were shown to have a marked effect on viscosity (79). 

Taylor (T4, T6), in two other articles, used the dispersed plug-flow model for turbulent flow, and Aris s treatment also included this case. Taylor and Aris both conclude that an effective axial-dispersion coefficient Dzf can again be used and that this coefficient is now a function of the well known Fanning friction factor. Tichacek et al. (T8) also considered turbulent flow, and found that Dl was quite sensitive to variations in the velocity profile. Aris further used the method for dispersion in a two-phase system with transfer between phases (All), for dispersion in flow through a tube with stagnant pockets (AlO), and for flow with a pulsating velocity (A12). Hawthorn (H7) considered the temperature effect of viscosity on dispersion coefficients he found that they can be altered by a factor of two in laminar flow, but that there is little effect for fully developed turbulent flow. Elder (E4) has considered open-channel flow and diffusion of discrete particles. Bischoff and Levenspiel (B14) extended Aris s theory to include a linear rate process, and used the results to construct comprehensive correlations of dispersion coefficients. 

ELEVATED TEMPERATURE HPLC FOR HIGH-SPEED SEPARATION-EFFECTS ON VISCOSITY AND COLUMN EFFICIENCY... 

On the other hand, if the cure rate is much faster than the phase separation, then the morphology is controlled by the cure rate through a chemical pinning process. In this system, phase separation is mainly controlled by the cure rate of the epoxy matrix. Faster curing rates and shorter gel times lead to smaller PEI-rich particles with an increasing cure temperature. The temperature effect on the viscosity of reaction mixture is relatively small (i.e., the complex viscosities measured by Physica are 7 and 4 Pa.s at curing temperatures of 150 and 190°C, respectively). 

In the composition range where the nodular morphology was shown, because the matrix (PEI phase) contained relatively small amount of epoxy, the temperature effect on the viscosity was larger than the reaction effect. Thus, the viscosity of the PEI matrix in the nodular morphology became reduced as the cure temperature was increased, which made epoxy nodules coalesce more easily with each other. As the cure temperature is increased, the viscosity of the PEI-rich matrix decreases from 210 Pa.s at 150°C to 50 Pa.s at 190°C. 

The physical factors include mechanical stresses and temperature. As discussed above, IFP is uniformly elevated in solid tumors. It is likely that solid stresses are also increased due to rapid proliferation of tumor cells (Griffon-Etienne et al., 1999 Helmlinger et al., 1997 Yuan, 1997). The increase in IFP reduces convective transport, which is critical for delivery of macromolecules. The temperature effects on the interstitial transport of therapeutic agents are mediated by the viscosity of interstitial fluid, which directly affects the diffusion coefficient of solutes and the hydraulic conductivity of tumor tissues. The temperature in tumor tissues is stable and close to the body temperature under normal conditions, but it can be manipulated through either hypo- or hyper-thermia treatments, which are routine procedures in the clinic for cancer treatment. 

Figure I 1.7. Variation of viscoelastic scaling factors with gas content for PS-C02 and PDMS-C02 systems. Lower scaling factor values for PS-C02 system, compared with PDMS-C02 system, are due to the closer proximity of the experimental temperatures to Tg of the pure polymer. The top curve displaying results for iso-free volume dilution of high-Mw polystyrene by low-Af polystyrene represents the effect on viscosity of volumetric dilution of high-Mw chains. Viscosity reductions for polymer-gas systems are significantly lower than the iso-free volume dilution curve, indicating that viscosity reduction is primarily due to free volume contributed by dissolved gas.

The temperature effect on the viscosity of solvents can be described by Andrade s equation... 

Saltiel, J. and D Agostino, J. (1972) Separation of viscosity aand temperature effects on the singlet pathway to stilbene isomerization, J. Am. Chem. Soc. 94 6445-6456. 

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