Styrene-polystyrene system

Fig. 8. Comparison of the measured and predicted exit concentrations obtained by Latinen for a styrene-polystyrene system. Reproduced with permission from Latinen (1962). Copyright 1982 American Chemical Society.

Solution We approximate the styrene-polystyrene system by using a toluene-polystyrene system. For this, the viseosity ean be estimated by... 

Addition of poly(styrene-block-butadiene) block copolymer to the polystyrene-polybutadiene-styrene ternary system first showed a characteristic decrease in interfacial tension followed by a leveling off. The leveling off is indicative of saturation of the interface by the solubilizing agent. 

This method was first applied by McCormick27 and by Bywater and Worsfold11 to the system a-methylstyrene/poly-a-methyl-styrene, and the free energy, entropy and heat of polymerization as well as the ceiling temperature were determined. Similar studies concerned with the system styrene/polystyrene are being carried out in our laboratories. 

In a system of significant interest to the present works, Graillard, et al. [62] studied the ternary phase diagrams of the systems polybutadiene-styrene-polystyrene and polybutadiene-block-polystrene-styrene-polystyrene. They showed that the presence of block copolymer increased the miscibility of the two poljrmers, as the styrene component polymerized. Similar effects are probable in the IPN s, as compared with the corresponding blends. 

Various problems may be encountered in thermodynamic investigations of living polymers. An instructive example is provided by the studies of the styrene-living polystyrene system as reported recently by... 

Although there is dispute about the exact oxidation state of titanium in the active species [Ti(III) or Ti(IV)], it was suggested, from the results of ESR measurements, that Ti(III) species form highly active sites for producing syndiotactic polystyrene in styrene polymerisation systems with the TiBz4—[Al(Me)0]x catalyst [50]. The moderately low catalyst activity is attributable to the stability of the benzyl transition metal derivatives towards reduction. 

The system with which we have begun our investigations is the styrene-dimethylsiloxane system. The dimethylsiloxane blocks should be considerably less compatible with polystyrene blocks than either polybutadiene or polyisoprene since the solubility parameter of dimethylsiloxane is much farther from that of polystyrene than are the solubility parameters of polybutadienes or of polyisoprenes (17), no matter what their microstructure. Furthermore, even hexamers of polystyrene and of polydimethylsiloxane are immiscible at room temperature and have an upper critical-solution temperature above 35°C (18). In addition, the microphases in this system can be observed without staining and with no ambiguity about the identity of the phases in the transmission electron microscope (TEM) silicon has a much higher atomic number than carbon or oxygen, making the polydimethylsiloxane microphases the dark phases in TEM (19,20). 

Saeki, S. Narita, Y. Tsubokawa, M. Yamaguchi, T., "Phase Separation Temperatures in the Polystyrene-Poly(alpha-methyl styrene)- Methylcyclohexane System," Polymer, 24, 1631 (1983). 

As shown In Figure 4, the rate of polymerization of styrene was retarded by good nonvlscous solvents such as benzene, cyclohexane, and octane whose solubility parameters (6) were within 1.5H of that of polystyrene at styrene to additive ratios of 3 to 1. The absolute rates were slightly Increased In poorer nonvlscous solvents such as heptane and hexane and were fastest In viscous nonsolvents such as dllsoctyl phthalate and Nujol. Rate studies Indicated a Rp dependency on [E] substantially greater than unity for the styrene emulsion systems modified with viscous poor solvents. 

Figure 3.4 Ternary phase diagram for the system styrene-polystyrene-polybutadiene rubber. Reproduced with permission from Encyclopedia of Polymer Science and Engineering, Mark (Ed.), John Wiley Sons, NY. Copyright John Wiley Sons...

If the addition of pentane occurs at 60-70% conversion, two influences result an increase in pressure due to the arranged loss of soluble styrene with increasing conversion, and a decrease in pressure because of increasing diffusion of pentane into the beads. The equilibrium pressure for the quaternary system styrene-polystyrene-isopentane-n-pentane has been calculated by Wolfahrt [27] for different conversions, temperatures and //-/isopentane ratios using a thermodynamic sorption model based on chain-of-rotators equation-of-state. 

The grafting is accomplished in the commercial mass polymerization process by polymerizing styrene in the presence of a dissolved rubber. Dissolving the elastomer in the styrene monomer before polymerization produces HIPS grades. Since the two polymer solutions are incompatible, the styrene-rubber system phase separates very early in conversion. Polystyrene forms the continuous phase, with the rubber phase existing as discrete particles having occlusions of polystyrene. Different production techniques and formulations allow the rubber phase to be tailored to a wide range of properties. Typically ... 

The morphology of the rubber-modified polystyrenes system involves some complex aspects, such as particle size, size distribution, occlusions of polystyrene inside the rubber phase, interfacial bonding between the rubbery particles and the brittle matrix, etc. Many authors have observed that some of the most important factors in controlling the mechanical properties of HIPS and ABS are rubber particle size [49], volume fraction of the rubbery phase (rubber + occluded polystyrene) [50,51] and the degree of graft [52]. Grafting occurs during the polymerization of styrene when some of the free radicals react with the rubber... 

Table I. Phase Data for the Styrene/Polystyrene/Polybutadiene System...

Figure 1. Triangular phase diagram for the system styrene / polystyrene / polybutadiene...

Plastics. Plastics denotes the matrix thermoplastic or thermoset materials in which additives are used to improve the performance of the total system. There are many different types of plastics that use large volumes of chemical additives including (in order of total additive consumption) polyvinyl chloride (PVC), the polyolefins [polyethylene (PE) and polypropylene (PP)], the styrenics —[polystyrene (PS) and acrylonitrile butadiene styrene (ABS)], and engineering resins such as polycarbonate and nylon. 

This means that these domains could be at their gel effect condition. However, this may not be entirely true because the end of the rise in conversiontime data may not coincide with the glass effect of the reactor system. In the polystyrene/styrene/ether system, the polymer-rich phase can be conservatively taken to contain about 28 wt% polystyrene, 7 wt% S, with the rest as ether (Fig. 2.3.1). This corresponds to a glass transition temperature of -80°C, which is well below that of the operating temperature of 80" C. In the calculations, Tg or Tin values are 100 C for polystyrene (Fried, 1995), -3PC for styrene (Fried, 1995), and -116 C for ether (Dean, 1985). 

In this section, effects of the current nonreactive version coil-globule transition in the FRRPP process was introduced using thermodynamic, transport phenomena, and kinetic concepts. Mathematical modeling efforts were applied to the polystyrene/styrene/ether system. This involved a probe into the model predictions... 

Thermodynamics of Ternary Polystyrene/Styrene/Ether System... 

Parameters used for the calculations of temperature profiles of large particles for the polystyrene/styrene/ether system are shown in Table 2.4.4. 

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