Polystyrene concentration

For concentrated polystyrene solutions (c>c ) in n-butylbenzene, Graessley and co-workers [36] observed that the shift factor hconc depends on the number of entanglements per macromolecule E. 

Rheological Studies of Aqueous Concentrated Polystyrene Latex Dispersions with Adsorbed Poly(vinyl alcohol) Layers... 

In this paper we report some rheological studies of aqueous concentrated polystyrene latex dispersions, in the presence of physically adsorbed poly(vinyl alcohol). This system has been chosen in view of its relevance to many practical systems and since many of the parameters needed for interpretation of the rheological results are available (15-18). The viscoelastic properties of a 20% w/w latex dispersion were investigated as a function of polymer coverage, using creep measurements. 

The sensitized photo-Fries rearrangement of 55 in benzene, toluene, and in concentrated polystyrene solution in dioxane is effectively quenched with biacetyl.4 This phenomenon must again be attributed to quenching of the aromatic energy donor, because in pure dioxane the photorearrangement of 55 is not influenced by biacetyl (vide supra). 

Cosgrove and Warren 33) used the PGSE method of Packer, et al. 9). with the Meiboom-Gill rf pulse sequence 7> to investigate concentrated polystyrene solutions. 

Fig. 8.10. Viscosity-shear rate master curve for concentrated polystyrene-n-butyl benzene solutions. The data were obtained for molecular weights ranging from 160000 to 2400000 concentrations from 0.255 to 0.55 gm/ml, and temperatures from 30° C to 60° C (155)...

For shear strains greater than approximately 2 the ratio cr(r)/> 0 for a concentrated polystyrene solution was reduced at all observable times. For the large strains, relaxation proceeded more rapidly at short times, but at longer times the residua] stress decayed with about the same time dependence as that in the linear viscoelastic region. 

Holmes,L.A., Kusamizu,K., Osaki,K., Ferry.J.D. Dynamic mechanical properties of moderately concentrated polystyrene solutions. J. Polymer Sci. Pt. A-2 9, 2009-2021 (1971). 

Quadrat, O., PodneekaJ. Influence of the thermodynamic quality of a solvent upon the viscosity of moderately concentrated polystyrene solutions. Collection Czech. Chem. Commun. 37,2402-2409 (1972). 

Einaga,Y., Osaki,K., Kurata,M, Tamura,M. Creep behavior of polymer solutions. II. Steady-shear compliance of concentrated polystyrene solutions. Macromolecules 4, 87-92 (1971). 

Sell.J.W., Foreman,W.C. Loss moduli under steady shearing of concentrated polystyrene solutions. Macromolecules 5,23-24 (1972). 

For systems where the stress-optical rule applies, birefringence measurements offer several advantages compared with mechanical methods. For example, transient measurements of the first normal stress difference can be readily obtained optically, whereas this can be problematic using direct mechanical techniques. Osaki and coworkers [26], using a procedure described in section 8.2.1 performed transient measurements of birefringence and the extinction angle on concentrated polystyrene solutions, from which the shear stress and first normal stress difference were calculated. Interestingly, N j was observed to... 

B. E. Zebrowski and G. G. Fuller, Rheooptical studies of concentrated polystyrene solutions subjected to transient simple shear flow, J. Polym. Sci., Polym. Phys. Ed., 23, 575 (1985). 

P. N. Dunlap and L. G. Leal, Dilute polystyrene solutions in extensional flow birefringence and flow modification, J. Non-Newt. Fluid Mech., 23, 5 (1987). E. Geffroy and L. G. Leal, Flow birefringence studies of a concentrated polystyrene solution in a two-roll mill. 1. Steady flow and start-up of steady flow, J. Polym. Sci., Polym. Phys., 30,1329 (1992). 

FIGURE 12.10 Reduced torque versus strain following flow reversal for hard sphere suspension of various concentrations. Polystyrene spheres 45 pm in diameter in silicone oil. Taken from Gadala-Maria and Acrivos [34]. 

Concentrated Polystyrene Solutions. We also applied our model to the data of Bueche (10) in the polystyrene-diethylbenzene system. These... 

A notable feature of the model is the postulation of an expression relating aggregation of polymer chains to concentration and the solvent power of the diluent. The excellent agreement between prediction and observation for solutions of short oil alkyd resins is taken as evidence for the importance of aggregation effects on viscosity in these systems. In addition, the accurate description of the molecular weight dependence of the viscosities of concentrated polystyrene solutions is an indication of the general applicability of the model. 

Fig. 21. Influence of concentration B the average number of broken bonds per chain (Eq. (38)) vs. degradation time for three different polymer concentrations (polystyrene in nms-decalin Uo denotes the nonuniformity of the starting molecular weight distribution (P,.o/Pd,o — 1) and AT is the distance to the dembdng temperature...

Fig. 22. B , the maximum number of broken bonds (cf. Eq. (40)) per chain vs. polymer concentration (polystyrene in fraw-decalin )...

Having established that the multi-wavelength transmission techniques offer a number of advantages, the Uv-vis reflectance spectra from concentrated polystyrene lattices have been recorded using fiber optics reflection probes. Although some averaging of the individual particle properties can be expected, reliable calibration and estimation of the particle properties is possible, since discrimination to the desired particle properties is found as it will be shown below. 

The particle size dependence of thermophoresis has been extensively studied for dilute polystyrene beads dispersed in aqueous solutions with very thin electric double layers under pH conditions of 7 8. The results of these investigations however are controversial and inconclusive. As shown in Fig. 6, Duhr and Braun [2] reported that the thermal diffusion coefficient Dj is proportional to particle diameter at room temperature by using the fluorescence detection method. Although Braibanti et al. [10] observed a similar dependence of Dj on particle size at a temperature of 45 °C through the beam deflection method, they found independence of with particle size at room temperature and at 5 °C, as shown in Fig. 6. In addition, for concentrated polystyrene beads at a temperature of 50 °C, Dj is not found to be dependent on particle size. 

A classic example is the master curve obtained for concentrated polystyrene solutions in n-butylbenzene (94). The method is also applicable for dilute aqueous solutions of poly(acrylamide), xanthan gum and poly(ethylene oxide). In the case of polyelectrolytes, the method gives satisfactory results only in limited concentration ranges. Further refinements have to be added to the general method (95). 

Fig. 49. Shear stress a (O) and normal stress vs (o) responses to a two-step step-up type of deformation history with y i = 1.47 and y2 = 2.90 for a concentrated polystyrene solution. The solid lines are the predictions for the K-BKZ or DE-IA equations and the dashed lines are for the DE-NIA equations. After Osaki and et al. (138), with permission.

Fig. 53. Shear stress response to half-step type of deformation history for a concentrated polystyrene solution and for different values of the first step duration t. Dotted line (i = 1 s dashed line = 4 s solid line = 16 s. After Brown and Burghardt (134), with...

Viovy JL, Monnerie L (1986) A study of local chain dynamics in concentrated polystyrene solutions using fluorescence anisotropy decay. Polymer 27(2) 181-184. doi 10.1016/0032-3861(86)90323-x... 

SCH Schick, M.J., Doty, P., and Zimm, B.H., Thermodynamic properties of concentrated polystyrene solutions, J. Amer. Chem. Soa, 72, 530,1950. 

Second, data for the somewhat more concentrated polystyrene solutions of Ashare whose primary normal stress differences are portrayed in Fig. 2-10 are represented by curves B and C. At 1% concentration, where the molecules overlap somewhat but are probably not entangled, there is a moderate drop in r/, somewhat more than in the extremely dilute solution at 5% concentration, where entanglements probably exist, the non-Newtonian effect is much more pronounced and, over about two decades of 7, ri follows rather closely a power-law relation. It is of interest that the onset of non-Newtonian flow occurs at a much higher shear rate for 1% than for 5% concentration, just as the normal stress differences achieve significant magnitudes at a higher shear rate for 1% than for 5% concentration in Fig. 2-10. Quantitative correlations will be introduced in later chapters. 

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