Viscosity temperature curves

Fig. 3. - Typical viscosity-temperature curve viscosity ranges for the important processing technologies, and definitions of fixed viscosity points...

The density, distillation curve, viscosity, and behavior at low temperature make up the essential characteristics of diesei fuel necessary for satisfactory operation of the engine. 

A complete viscosity—temperature curve is shown ia Figure 3 for Amersil commercial-grade fused quartz. A number of studies have showa that, above 1000°C, the viscosity, Tj, of vitreous sdica follows the geaeral relatioa... 

Fig. 3. Viscosity—temperature curve for Amersil commercial-grade sdica where the dashed line represents iaterpolation between data sets (139,140).

Figure 15.11. Viscosity-temperature curves for poly(methyl methacrylate) and other thermoplastics. (Reproduced by permission of ICI)...

Figure 29.2. Viscosity-temperature curves for four commercial dimethylpolysiloxane fluids and for liquid paraffin. The numbers 1000, 300, 100 and 40 indicate the viscosities in centistokes at 38°C.

Figure 8.1. Generalised viscosity vs. temperature curve for liquids...

PPG (at higher temperatures) behaves like a typical pseudoplastic non-Newtonian fluid. The activation energy of the viscosity in dependence of shear rate (284-2846 Hz) and Mn was detected using a capillary rheometer in the temperature range of 150-180°C at 3.0-5.5 kJ/mol (28,900 Da) and 12-13 kJ/mol (117,700 Da) [15]. The temperature-dependent viscosity for a PPG of 46 kDa between 70 and 170°G was also determined by DMA (torsion mode). A master curve was constructed using the time-temperature superposition principle [62] at a reference temperature of 150°G (Fig. 5) (Borchardt and Luinstra, unpublished data). A plateau for G was not observed for this molecular weight. The temperature-dependent shift factors ax were used to determine the Arrhenius activation energy of about 25 kJ/mol (Borchardt and Luinstra, unpublished data). 

In addition to these four, Greenhoe also described two more hot bench transition points in the temperature region below the gel point. As shown in Figure 2, these were superimposed on the well known viscosity/temperature curve. The transition points are defined as follows ... 

The temperature at which the fluid plastisol becomes dry and puttylike he defined as the hot bench fluid point. The vertical line corresponding to this temperature cuts the viscosity/temperature curve of the plastisol at a point where the viscosity is rising rapidly. 

The temperature where the puttylike plastisol changes to a dry crumbly solid, which is just above the temperature where the plastisol loses its identity as a fluid in the viscosity/temperature curve, he defined as the hot bench dry point. ... 

Figure 5. Viscosity/temperature and tensile strength/temperature curves...

Fig. II.1. Viscosity-temperature curves for some common laboratory glasses. The numbers in parentheses correspond to Corning designations. (Adapted from Corning Glass Works, Corning, NY, Bulletin B-83. 1957.)...

Another interesting observation is that at room temperature (small viscosity condition) and for the different alcoholic solutions (where the B emission due to the backward reaction B <— A is negligible), a straight line with slope very close to unity has been found (Fig. 5.5) for the curve log versus log 17, where is the relative fluorescence quantum yield of the B state deduced from stationary spectra with B = 1 in cyclohexane. 

Similar reactions are the hydrogenation of lubricating oils, whereby oils with a flatter viscosity-temperature curve are produced, as well as low-temperature hydrogenation of brown-coal tar, which became known as the TTH process. Although in these two processes the bulk of the feedstock remains liquid and reacts as liquid with hydrogen on the fixed-bed catalyst, the path of the reaction is the same as in the vapor-phase operation. 

At temperatures above the softening point, isotropic pitch often displays Newtonian flow characteristics (18,19), but this may well depend upon the concentration of any insoluble particles (i.e., primary QI in the case of coal tar based materials) present within the pitch. A high concentration of QI could lead to non-Newtonian character as a result of the particle-particle attractive forces. Figure 3 shows n -T curves for a variety of pitch materials and their pyrolysis products. Pyrolysis increases the Tg of the system and shifts the viscosity-temperature curve to higher temperatures. 

Figure 3. Typical viscosity-temperature curves for a variety of isotropic pitch samples and partially pyrolysed pitches.

Effect of the dispersed phase on the apparent viscosity-temperature curve. Maxima do not always appear in the apparent viscosity-temperature curves. A recent report (25) shows that the appearance of the maximum in the D - HTT curve could be an artifact produced by experimental procedure. Whilst this is undoubtedly the case in some systems, whether it is always the case is not yet clear. At this stage it will suffice to review factors that may be important in determining the form of these 11 in-situ1 results. 

Figure 2. Viscosity-temperature curves for SCT-pitch, coal tar pitch, and a petroleum pitch.

For a number of polymer solutions experimental data on the effect of temperature on viscosity are available. By way of example, Fig. 16.4 shows log t] against 1/T for polystyrene in xylene, together with the curve for the melt and the straight line for the pure solvent. 

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