Effect on viscosity

The molecules used in the study described in Fig. 2.15 were model compounds characterized by a high degree of uniformity. When branching is encountered, it is generally in a far less uniform way. As a matter of fact, traces of impurities or random chain transfer during polymer preparation may result in a small amount of unsuspected branching in samples of ostensibly linear molecules. Such adventitious branched molecules can have an effect on viscosity which far exceeds their numerical abundance. It is quite possible that anomalous experimental results may be due to such effects. 

Thickeners. These are used to kicrease viscosity of shampoos to achieve certain consistency characteristics ki the product, from a thickened Hquid to gels and pastes. Among the most important materials used for this purpose are the alkanolamides. The chain length of the amide alkyl group and its solubiHty ki the shampoo system are important aspects to be considered ki thek use for effects on viscosity. In general, as the chain length increases the viscosity response improves. The viscosity increase also is related to the water solubiHty of the amide the more water-soluble forms provide a lower viscosity response than the less soluble amides. 

CMC is compatible with most water-soluble nonionic gums over a wide range of concentrations. When a solution of CMC is blended with a solution of a nonionic polymer such as hydroxyethjlceUulose or hydroxypropylceUulose, a synergistic effect on viscosity is usuaUy observed. Such blends... 

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. 

Figure 12.26. Effect on viscosity of partial replacement of a PVC paste polymer (Breon PI30/1) in a PVC paste with a non-porous suspension polymer of high packing density. (The Distillers...

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. 

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

Being compared to conventional Reynolds equations, /12 can be regarded as a modification coefficient of the micropolar effects on viscosity, and its effects are shown in Fig. 8. This shows that the microstructure and microrotation will add an increase in lubricant viscosity. When the ratio hH increases, the viscosity enhancement decreases further increasing the ratio, the modiflcation approaches unit. Because I is related to the molecular size, and h is the film gap, this means that if the problem scale is much larger than the molecular dimension, microrotation and the microstructure of particles will contribute msignrhcantly to the macroscopic properties. The larger N is, the more the increase is, as also evidenced by Fig. 8. 

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. 

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. 

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). 

Elevated Temperature HPLC for High-Speed Separation—Effects on Viscosity... 

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

As high doses these internal links would be expected to produce looped structures, with a marked effect on viscosity. No such effect is observed. To explain this, we must assume that the radicals, trapped in the crystalline regions, migrate to the surface where the molecular loops are found (corresponding to some extent to the old amorphous... 

This discussion indicates that only small beneficial effects are possible on addition of solids and that addition of heavy salts, which could increase density without an appreciable effect on viscosity, would appear more interesting heat transfer mediums than suspensions. It is possible that in these systems too, however, the effects would usually not be of sufficient magnitude to warrant the complications introduced. 

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.

Product oil containing 24 percent asphaltenes of 670 molecular weight has a viscosity of 86 (SSF at 180° F, ASTM D88), while product oil containing almost the same amount of asphaltenes (22 percent) but with a molecular weight of 460 has a viscosity of only 14. Benzene insolubles, heretofore regarded as unreacted coal, were found to be soluble in pyridine and to exert a large effect on viscosity. 

Particle asymmetry has a marked effect on viscosity and a number of complex expressions relating intrinsic viscosity (usually extrapolated to zero velocity gradient to eliminate the effect of orientation) to axial ratio for rods, ellipsoids, flexible chains, etc., have been proposed. For randomly orientated, rigid, elongated particles, the intrinsic viscosity is approximately proportional to the square of the axial ratio. 

Urea formaldehyde and thiourea resins were reported to have a protective effect on viscose rayon and cotton fabrics upon exposure to... 

Silica nanoparticles are a promising component of FR systems because of their effect on viscosity in the molten state and the potential ability to react with many other chemical compounds, particularly during degradation stages of filled polymers. 

Viscose In principle all the treatments effective on cotton should be effective on viscose as well. However, the delicate viscose libers cannot withstand the harsh finishing processes, and are rarely treated with a finish. However, Lyocell (Coutaulds) can be treated with Pyrovatex CP (Ciba) to produce FR Lyocell.55 The work at Bolton has shown that this fiber being more reactive than cotton needed only half the normal amount of this FR treatment applied to cotton cellulose to produce an equivalent degree of flame resistance. 

One issue is that most metal complexes formed in ionic liquids are anionic and these will have a significant effect on viscosity and mass transport. The effect of metal ion concentration on reduction current will therefore not be linear. Relative Lewis acidity will affect mass transport, ionic strength and speciation and accordingly the nucleation and growth mechanism of metals would be expected to be concentration dependent. 

Figure 3 Viscosity profile of a 0.05% CMC sol, showing the effect on viscosity of order of addition of tartaric acid (TA) to water (a) before and (b) after dispersion of CMC.

Particle interactions resulting in aggregates of particles will adversely affect dispersion. Special surface treatments are provided to reduce these aggregation forces and achieve higher loadings and better suspension stability with less effect on viscosity. These surface treatments can be applied directly to the filler, and many grades of treated fillers are commercially available. 

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