Polyisobutylene fluid

Puskas, J.E., Pattern, W.E., Wetmore, P.M., and Krukonis, A. Synthesis and characterization of novel six-arm star polyisobutylene-polystyrene block copolymers. Rubber Chem. TechnoL, 72, 559-568, 1999. Puskas, J.E., Wetmore, P.M., and Krukonis, A. Supercritical fluid fractionation of polyisobutylene-polystyrene block copolymers, Polym. Prepr., 40, 1037-1038, 1999. 

High-Temperature Defoamers. Polyisobutylene compounds are particularly effective in high-temperature (300° to 1 XX)° F) treatments of hydrocarbon fluids [786,788], such as during the distillation of crude oil and coking of crude oil residues. Polyisobutylene compounds are less expensive than silicone-based compounds. 

Similarly, the polymerization process will pull the isobutylene selectively out of the C4 stream. Polyisobutylene is used mainly as a viscosity index improver in lubricating oils and in caulking and sealing compounds. Some of the low molecular weight polyisobutylenes are particularly suited for use in the construction field because it doesn t solidify. They remain a tacky fluid and when properly formulated with clay fillers, etc., take on the properties of a sticky, putty-like substance. 

Fig. 1.4 gives such a plot, which was prepared by Philippoff (8,9) from his early measurements on a 15 per cent solution of polyisobutylene (P-100) in decalin (measurement temperatures 30 and 50°C). From this figure it is clearly seen that An as a function of p21 is non-linear. In contrast to the above mentioned solution of S 111 in methyl 4-bromo-phenyl carbinol, the solution of the poly-isobutylene P-100 in decalin does not form a second order fluid. However, for the product A n sin 2%, one obtains a beautiful straight line. The stress-optical law seems to hold also for this more general type of fluid. ... 

This section will deal with suppression of flow in extension of molten polymers in the region of significant elastic strains21 24 . The study of polyisobutylene 11-20 23,35) failed to reveal such phenomena (the velocity of irreversible strain ep = d(ln[3)/dt increased strictly with time). Retardation of polymer fluid flow is considered on the example of homogeneous extension at constant strain velocity and force. Most experiments were carried out with commercial low-density polyethylene (LDPE) with molecular weight MW 105. Figure 7 gives experimental dependencies of tensile force F/S0 and irreversible strain In 3 ( 3 = e/ot) upon time t at different... 

To reach steady state, the residence time of the fluid in a constant stretch rate needs to be sufficiently long. For some polymer melts, this has been attained however, for polymer solutions this has proved to be a real challenge. It was not until the results of a world wide round robin test using the same polymer solution, code named Ml, became available that the difficulties in attaining steady state in most extensional rheometers became clearer. The fluid Ml consisted of a 0.244% polyisobutylene in a mixed solvent consisting of 7% kerosene in polybutene. The viscosity varied over a couple of decades on a logarithmic scale depending on the instrument used. The data analysis showed the cause to be different residence times in the extensional flow field... 

Fig. 3.3 A 9, 52-mm D aluminum rod rotating at 10 rps in a wide-diameter cylinder containing (a) Newtonian oil, and (b) polyisobutylene (PIB) solution, which exhibits the rod-climbing Weissenberg effect [from G. S. Beavers and D. D. Joseph, J. Fluid Mech., 69, 475 (1975)]. (c) Schematic representation of the flow direction flow-induced causing rod climbing. For Newtonian fluids, Tn = 0, since the small and simple Newtonian fluid molecules are incapable of being oriented by the flow.

Kaplan and Tadmor (73) expanded the model to include leakage flow effects, considered non-Newtonian fluids, and verified the model experimentally with a polyisobutylene. We discuss the flow further in a tangential, nonintermeshing TSE in Chapter 10. 

Adhesives on the basis of a rubber are applied as watery dispersions, as solvents, or as solvent-free fluids. Sometimes the rubber is vulcanised after the gluing process, sometimes it remains uncured. Polymers often used are butyl rubber, polyisobutylene, and polychloroprene. A more recent development is the use of... 

Figure 3.2 Trouton ratio, Tr, of uniaxial extensional viscosity to zero-shear viscosity jq after start-up of steady uniaxial extension at a rate of 1 sec i for a Boger fluid consisting of a 0.185 wt% solution of flexible polyisobutylene (Mu, = 2.11 x 10 ) in a solvent composed mostly of viscous polybutene with some added kerosene (solid line). The dashed line is a fit of a multimode FENE dumbbell model, where each mode is represented by a FENE dumbbell model, with a spring law given by Eq. (3-56), without preaveraging, as described in Section 3.6.2.2.I. The relaxation times were obtained by fitting the linear viscoelastic data, G (co) and G"(cu). The slowest mode, with ri = 5 sec, dominates the behavior at large strains the best fit is obtained by choosing for it an extensibility parameter of = 40,000. The value of S — = 3(0.82) n/C(x, predicted from the...

GR1 Gregg, C.J., Stein, P.S., and Radosz, M., Phase behavior of telechelic polyisobutylene (PIB) in subcritical and supercritical fluids I., Macromolecules, 27, 4972, 1994. 

Figure 2.23. The reduced surface tension as a function of the reduced temperature for a number of polymers (A, poly(vinyl acetate) , polystyrene , polyisobutylene A, poly(dimethyl siloxane) , linear polyethylene o, branched polyethylene), compared with the prediction of a gradient theory using the Poser and Sanchez lattice fluid model and a square gradient term modified to account for loss of polymer configurational entropy near a surface (full line). After Sanchez (1992).

The only drag measurements on nonspherical particles (cylinders, bars) in viscoelastic fluids are due to Rodrigue et al. (1984). They measured free-settling velocities in a polyisobutylene in kerosene/polybutene solution (Boger fluid), with a fluid relaxation time of 7.2 msec. They found it necessary to modify Eq. (16) by incorporating the following correction factor due to viscoelasticity ... 

Common VI improvers which are added to lubricants are high molecular weight ( 20,000 g/ mol) polymers. These tend to increase the viscosity of the oil to a greater extent at high temperatures than at low temperatures. Examples of polymers added include polymethacrylates, polyacrylates, polyisobutylenes, and alkylated styrenes. VI improvers are used in engine oils and automatic transmission fluids. The effect of a VI additive to an oil is shown in Fig. 8.7. 

Polyisobutylene (PIB) fluids are produced by the oligomerization of isobutylene in a mixed C4 stream over a BF3 or AICI3 catalyst. PIB are seldom used by themselves. They are typically used as blend stocks or as additives to increase lubricant viscosity. Table 10 summarizes the typical properties of selected PIB fluids . The VI and pour points of PIB are comparable to those of conventional mineral oil. PIB usually have a lower flash point and decompose easily into monomer at 200°C and higher. The advantages of PIB are their high compatibility with most synthetic or mineral base stocks and their relatively low cost compared to other synthetic base stocks. 

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