Phase behavior, polymers polystyrene

Kambour RP, Bendler JT, Bopp RC (1983) Phase behavior of polystyrene, poly(2,6-dimethyl-l,4-phenylene oxide), and their brominated dtaivatives. Macromolecules 16 753-757 Koningsveld R, Kleijens LA (1971) Liquid-liquid phase separation in multicomponent polymer systems. X. Concentration dependence of the pair-interaction parameter in the system cyclohexane-polystyrene. Macromolecules 4 637-641 Maron SH (1959) A theory of the thermodynamic behavior of non-electrolyte solutions. J Polym Sci 38 329-342... 

C02 Cowie, J.M.G. and McEwen, I.J., Polymer-cosolvent systems. 6. Phase behavior of polystyrene in binary mixed solvents of acetone with n-alkanes examples of classic cosolvency . Polymer, 24, 1449,1983. 

TSE Tseng, H.-S., Lloyd, D.R., and Ward, T.C., Phase behavior of polystyrene-polyisoprene-toluene systems in the temperature range 15-45°C, J. Polym. Sci. Part B Polym. Phys., 29, 161, 1991. 

The high-pressure phase behavior of polymer-solvent-supercritical carbon dioxide systems was investigated experimentally The polymers used were poly(methyl methacrylate), polystyrene, polybutadiene, and poly(vinyl ethyl ether) at concentrations ranging from 5 to 10% in mixtures with toluene or tetrahydrofuran. The experiments were conducted for temperatures from 25 to 70°C and pressures up to 2200 psi in a high-pressure cell (Kiamos and Donohue, 1994). 

Before discussing theoretical approaches let us review some experimental results on the influence of flow on the phase behavior of polymer solutions and blends. Pioneering work on shear-induced phase changes in polymer solutions was carried out by Silberberg and Kuhn [108] on a polymer mixture of polystyrene (PS) and ethyl cellulose dissolved in benzene a system which displays UCST behavior. They observed shear-dependent depressions of the critical point of as much as 13 K under steady-state shear at rates up to 270 s Similar results on shear-induced homogenization were reported on a 50/50 blend solution of PS and poly(butadiene) (PB) with dioctyl phthalate (DOP) as a solvent under steady-state Couette flow [109, 110], A semi-dilute solution of the mixture containing 3 wt% of total polymer was prepared. The quiescent... 

In the previous section we have described the three types of phase behavior observed in the low-molecular-weight PMMA/PS system and reviewed the four types observed in the low-molecular-weight PS/PMMA system. These various phase relationships have been studied in terms of their dependence on the molecular weight (Mn) and weight percent (W) of the initial polymer present. Further, we have presented quantitative data concerning the sizes of the dispersed particles, again correlated to variations in Mn and W. In this section we will discuss the results in terms of the poly (methyl methacrylate )/polystyrene/styrene and poly-styrene/poly( methyl methacrylate)/methyl methacrylate ternary phase diagrams, whichever is appropriate. 

Phase Relationships. The first systematic investigation of the two-phase behavior of polymer/polymer/solvent systems was probably made by Dobry and Boyer-Kawenoki (2) for a variety of polymer pairs, and more recently this work was extended by Kern and Slocombe (3) and Paxton (35) to a number of other systems including several vinyl polymers. Typically, the three-component phase behavior is as shown in Figure 19 for the polystyrene/polybutadiene/benzene system (2), where a one-phase (polystyrene/polybutadiene/benzene) region is separated by a phase boundary from a two-phase (polystyrene-rich/benzene and polybutadiene-rich/benzene) mixture. As with any three-component system of this type, a critical point exists somewhere near the maximum of the phase boundary, and appropriate tie lines give the compositions and amounts of the respective phases in the two-phase region. 

Subsequently, more detailed studies have revealed two modes of phase behavior depending on the ratio of the sizes of the particle and the polymer (Gast et al, 1983a,b, 1986 Sperry, 1984 Vincent, 1987). For example, electrostatically stabilized polystyrene latices in aqueous solutions of dextran exhibit a simple fluid-solid transition for a/Rg = 6.9, but they exhibit a more... 

Robledo-Muniz, J. G. Tseng, H. S. Lloyd, D. R., "Phase Behavior Studies of the System Polystyrene-Polybutadiene- Chloroform. I. Application of the Flory-Huggins Theory," Polym. Eng. Sci., 25, 934 (1985). 

Stoffer and Bone (15.16) studied the phase behavior and morphology of polymers obtained by polymerization of w/o microemulsions. They observed that the cosurfactant pentanol acts as a chain transfer agent. They also found that the polymer formed in a microemulsion is as large as the droplet size in the macroemulsion, thus explaining problems encountered with phase separation. Gan, Chew and Friberg (17) studied the stability behavior of w/o microemulsions containing styrene and polystyrene with particular reference to the effects of pentanol and butylcellosolve. 

Figure 9 shows coexistence curves for polymers of 100, 600, 1000, and 2000 sites. The lines are the results of this work, and the open symbols are simulation data from the literature [25]. For n = 100 and n = 600, our results are in good agreement with literature reports. Note, however, that with the new method, we are able to explore the phase behavior of long polymer chains down to fairly low temperatures. The computational demands of the new method are relatively modest. For example, calculation of the full phase diagram for polymer chains of length 2000 required less than 5 days on a workstation. It is important to emphasize that, for the cubic lattice model adopted here, chains of 2000 segments correspond to polystyrene solutions... 

Recently the polymerization of styrene within lamellar and cubic phases of the surfactant DODAB (dioctadecyldimethylammonium bromide) was studied [50]. After polymerization, the polystyrene/water/DODAB system showed the same phase behavior as the binary water/DODAB system, a result suggesting a phase separation during polymerization into a polymer-rich (with M 400,000) and a lyotropic phase. 

The separation of polystyrene and polybutadiene into two phases, both containing styrene, was used to measure polymer-solvent interaction parameters. By this technique, the mean interaction parameter, for polystyrene in styrene is 0.49 and that for polybutadiene in styrene, Xis, is 0.29. Phase behavior at higher concentrations was calculated from data obtained at concentrations of less than 35%. As a result, phase behavior during polymerization of high impact polystyrene was interpreted. 

REB Rebelo, L.P. and van Hook, W.A., An imusual phase diagram the polystyrene-acetone system in its hypercritical region near tricritical behavior in a pseudo-binary solution, J. Polym. Sci. PartB Polym. Phys., 31, 895, 1993. 

LI1 Li, D., Han, B., Liu, Z., and Zhao, D., Phase behavior of supercritical C02/styrene/ poly(ethylene terephthalate) (PET) system and preparation of polystyrene/PET composites. Polymer, 42, 2331,2001. 

A. FIPN s, PDIPN s and linear blends of poly(2,6-dimethy1-1,4-phenylene oxide) and polystyrene all exhibited single phase behavior as evidenced by glass transition analysis and electron microscopy. Thus, for the first time, true interpenetrating polymer networks have been produced, i.e., homogeneous morphology with little or no possibilities of covalent bonds between the component pol3nners. 

We will discuss nematic ordering in polymer systems and we start with solutions of rigid rods as the simplest system in which isotropic-nematic transition occurs. Solutions of a flexible polymer and a nematic low molecular liquid crystal display at low polymer content, when cooled down from the isotropic phase, segregation into a nematic and an isotropic phase. At higher polymer content, the solution decays first in two isotropic phases, one rich in polymer, and the other poor in polymer. Further cooling leads to separation of the latter in a nematic phase very poor in polymer and the isotropic phase rich in polymer. This is sketched schematically in Figure 19. Phase behavior of the indicated type was observed in EBBA (/ -ethoxy benzylidene- w-4- -butylaniline) mixed with polystyrene (Ballauf, 1986 Lee et al., 1994) and with poly(ethylene oxide) (Kronberg et al., 1978). 

The effect of a simple shear flow on the phase behavior and morphology was investigated with the use of a parallel-plate apparatus (Fig. 8.4, Madbouly et al. 1999a) for some polymer mixtures poly(methyl methacrylate) (PMMA)/ poly(styrene-co-acrylonitrile) (SAN-29.5) and polystyrene (PS)/poly(vinyl methyl ether) (PVME), which have an LCST-type phase diagram PS/PMMA, which has a UCST-type phase diagram and polycarbonate (PC)/SAN and nylon4, 6(PA4,6)/ poly(phenylene sulfide) (PPS), which are immiscible in the whole measurable region under the quiescent state. 

For the description and prediction of thermodynamic data, e.g. volumetric and compositional derivatives of thermodynamic functions of state, many theoretical models are available. The Simha-Somcynsky theory can be considered to be very succesful if one is interested in the quantitative description of thermodynamic properties. Especially, for the equation of state properties this has been shown on many occasions. For the phase behavior of polymer systems, the theory hasn t been evaluated yet in great detail. In this contribution the influence of composition, temperature and molar mass distribution of the polymer is studied for the system polystyrene/cyclohexane. 

N. Devia, J. A. Manson, and L. H. Sperling, Simultaneous Interpenetrating Networks Based on Castor Oil Elastomers and Polystyrene. III. Morphology and Glass Transition Behavior, Polym. Eng. Sci. 19(12), 869 (1979). Castor oil-polyester/styrene SINs. Electron microscopy and Tg. Studies in phase domain formation. 

J. L. Thiele and R. E. Cohen, Synthesis and Characterization of Single-Phase Interpenetrating Polymer Networks, Polym. Prepr. 19(1), 137 (1978). Swelling and modulus behavior Polystyrene/polystyrene IPNs. Swelling equation. 

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