Styrene Polymer Solutions

Poly(ot-mcthyl styrene) Poly(2,4-dimethyl styrene) Poly(isopropyl a-methyl styrene) 

Vinyl Polymer Solutions Poly(vinyl acetate) 

Poly(2-vinyl pyridine) Poly(vinyl pyrrolidone) 

PolyCy-benzyl-L-glutamate) Poly(ethylene terephthalate) 

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Resin and Polymer Solvent. Dimethylacetamide is an exceUent solvent for synthetic and natural resins. It readily dissolves vinyl polymers, acrylates, ceUulose derivatives, styrene polymers, and linear polyesters. Because of its high polarity, DMAC has been found particularly useful as a solvent for polyacrylonitrile, its copolymers, and interpolymers. Copolymers containing at least 85% acrylonitrile dissolve ia DMAC to form solutions suitable for the production of films and yams (9). DMAC is reportedly an exceUent solvent for the copolymers of acrylonitrile and vinyl formate (10), vinylpyridine (11), or aUyl glycidyl ether (12). 

Phthahc resins are usually processed to an acid number of 25—35, yielding a polymer with an average of 1800—2000. The solution viscosity of the polymer is usually followed to ascertain the polymer end point. The resin is cooled to 150°C and hydroquinone stabilizer (150 ppm) is added to prevent premature gelation during the subsequent blending process with styrene at 80°C. The final polymer solution is cooled to 25°C before a final quaUty check and dmmming out for shipment. 

Depending on the concentration, the solvent, and the shear rate of measurement, concentrated polymer solutions may give wide ranges of viscosity and appear to be Newtonian or non-Newtonian. This is illustrated in Eigure 10, where solutions of a styrene—butadiene—styrene block copolymer are Newtonian and viscous at low shear rates, but become shear thinning at high shear rates, dropping to relatively low viscosities beyond 10 (42). The... 

Styrene is a colorless Hquid with an aromatic odor. Important physical properties of styrene are shown in Table 1 (1). Styrene is infinitely soluble in acetone, carbon tetrachloride, benzene, ether, / -heptane, and ethanol. Nearly all of the commercial styrene is consumed in polymerization and copolymerization processes. Common methods in plastics technology such as mass, suspension, solution, and emulsion polymerization can be used to manufacture polystyrene and styrene copolymers with different physical characteristics, but processes relating to the first two methods account for most of the styrene polymers currendy (ca 1996) being manufactured (2—8). Polymerization generally takes place by free-radical reactions initiated thermally or catalyticaHy. Polymerization occurs slowly even at ambient temperatures. It can be retarded by inhibitors. 

Low Conversion Reactors. The major problem in temperature control in low conversion reactors is the orders cf magnitude increase in viscosity as the conversion increases. Fig.8 shows the viscosity of a polystyrene solution as the function of percent PS. The data are for polystyrene with a Staudinger molecular weight of 60,000 at 100 C and 150 C in a cumene solution, a satisfactory analog for styrene monomer solutions. As the polymer concentration increases from 0 to 60%, viscosity increases from about 1 cp to 10 cp. 

HS-GC methods have equally been used for chromatographic analysis of residual volatile substances in PS [219]. In particular, various methods have been described for the determination of styrene monomer in PS by solution headspace analysis [204,220]. Residual styrene monomer in PS granules can be determined in about 100 min in DMF solution using n-butylbenzene as an internal standard for this monomer solid headspace sampling is considerably less suitable as over 20 h are required to reach equilibrium [204]. Shanks [221] has determined residual styrene and butadiene in polymers with an analytical sensitivity of 0.05 to 5 ppm by SHS analysis of polymer solutions. The method development for determination of residual styrene monomer in PS samples and of residual solvent (toluene) in a printed laminated plastic film by HS-GC was illustrated [207], Less volatile monomers such as styrene (b.p. 145 °C) and 2-ethylhexyl acrylate (b.p. 214 °C) may not be determined using headspace techniques with the same sensitivities realised for more volatile monomers. Steichen [216] has reported a 600-fold increase in headspace sensitivity for the analysis of residual 2-ethylhexyl acrylate by adding water to the solution in dimethylacetamide. 

Figure 11(A) shows a principle sketch of a SEC set-up. The eluent (solvent) is pumped at a constant flow rate through the system. A small amount of polymer solution (typically 200 pL) is injected manually or with an autosampler. The main part comprises a set of columns (typically 3-4 columns+pre-column) typically packed with microporous styrene-divinylbenzene, porous glass, or silica. In the routine analytical laboratory it is especially useful to have a pre-column in order to collect impurities that might be present in the samples. If many different samples are to be analyzed, it is necessary to check the reliability of the columns frequently to avoid artefacts due to residues from previous samples still held on the column. In order to avoid problems, samples should be purified before they...

Precipitation of the catalyst can be effected by treating the polymer solution with acid/base and/or oxidants. Poloso and Murray [95] proposed a method to recycle the nickel octanoate ((CH3(CH2)6C02)2Ni)/triethylaluminum((C2H5)3Al) catalyst from a styrene-butadiene polymer solution. The polymer solution containing the catalysts was refluxed with 4 wt.% glacial acetic acid (relative to polymer) for 4 h, followed by treatment with 1.4 wt.% anhydrous ammonia. The solution was then filtered through a diatomaceous earth. The nickel content in the polymer was decreased from 310 ppm to 5.6 ppm. 

Bulk and suspension polymerisation are the most commonly used techniques. In bulk polymerisation styrene is heated to 80°C for about 2 days to get a viscous solution of polymer in styrene. The solution is then fed to a tower wherein polymerisation is completed at 100°C, 150C° and 180C° stagewise. In suspension process, styrene is suspended in dimineralised water in presence of suspending agent and initiator like benzoyl peroxide and heated to 20°C. The product is washed with acid, water and dried. 

Preparation of Polymer VII. A solution of 8.0g (36 moles) 4-(l-phenylethoxy)-styrene and 0.080g AIBN in 16g toluene was heated in an oil bath at 75°C under inert atmosphere. After 48 hours the thick polymer solution was diluted with a minimum amount of toluene to allow its precipitation in 3L of petroleum ether. The recovered polymer (7.1g, 88% yield) had spectral properties in agreement with the proposed structure. 

V, is the molar volume of polymer or solvent, as appropriate, and the concentration is in mass per unit volume. It can be seen from Equation (2.42) that the interaction term changes with the square of the polymer concentration but more importantly for our discussion is the implications of the value of x- When x = 0.5 we are left with the van t Hoff expression which describes the osmotic pressure of an ideal polymer solution. A sol vent/temperature condition that yields this result is known as the 0-condition. For example, the 0-temperature for poly(styrene) in cyclohexane is 311.5 K. At this temperature, the poly(styrene) molecule is at its closest to a random coil configuration because its conformation is unperturbed by specific solvent effects. If x is greater than 0.5 we have a poor solvent for our polymer and the coil will collapse. At x values less than 0.5 we have the polymer in a good solvent and the conformation will be expanded in order to pack as many solvent molecules around each chain segment as possible. A 0-condition is often used when determining the molecular weight of a polymer by measurement of the concentration dependence of viscosity, for example, but solution polymers are invariably used in better than 0-conditions. 

Miyata and Nakashio [77] studied the effect of frequency and intensity on the thermally initiated (AIBN) bulk polymerisation of styrene and found that whilst the mechanism of polymerisation was not affected by the presence of ultrasound, the overall rate constant, k, decreased linearly with increase in the intensity whilst the average R.M.M. increased slightly. The decrease in the overall value of k they interpreted as being caused by either an increase in the termination reaction, specifically the termination rate constant, k, or a decrease in the initiator efficiency. The increase in kj(= kj /ri is the more reasonable in that ultrasound is known to reduce the viscosity of polymer solutions. This reduction in viscosity and consequent increase in Iq could account for our observed reductions [78] in initial rate of polymerisation of N-vinyl-pyrrolidone in water. However this explanation does not account for the large rate increase observed for the pure monomer system. 

Prepare ahead of time the polymer solutions poly(styrene) at 1 g in 100 ml (see Note 1). 

Prepare the polymer solutions in volumetric flasks ahead of time with concentrations for the poly(styrene) narrow distribution standards at 0.8g/liter and the polydisperse poly (styrene) at 1.2g/liter. 

Rubber-toughened polystyrene composites were obtained similarly by polymerising the dispersed phase of a styrene/SBS solution o/w HIPE [171], or a styrene/MMA/(SBS or butyl methacrylate) o/w HIPE [172], The latter materials were found to be tougher, however, all polymer composites had mechanical properties comparable to bulk materials. Other rubber composite materials have been prepared from PVC and poly(butyl methacrylate) (PBMA) [173], via three routes a) blending partially polymerised o/w HIPEs of vi-nylidene chloride (VDC) and BMA, followed by complete polymerisation b) employing a solution of PBMA in VDC as the dispersed phase, with subsequent polymerisation and c) blending partially polymerised VDC HIPE with BMA monomer, then polymerisation. All materials obtained possessed mixtures of both homopolymers plus some copolymer, and had better mechanical properties than the linear copolymers. The third method was found to produce the best material. 

Osaki, K., SchragJ.L. Viscoelastic properties of polymer solutions in high-viscosity solvents and limiting high-frequency behavior. I. Polystyrene and poly(a-methyl-styrene). Polymer J. (Japan) 2,541-549 (1971). 

Ferry,J.D, Grandine,L.D.,Jr., Udy.D.C. Viscosities of concentrated polymer solutions. III. Polystyrene and styrene-maleic acid copolymer. J. Colloid Sci. 8, 529-539 (1953). 

Regarding the improvement of overall economy of ABS and HIPS-production the polymerization of BD in the presence of styrene monomer is particularly worth mentioning (Sect. 3.3) [581-590]. By the implementation of this technology the total number of process steps and overall process complexity would be considerably reduced. In particular, the isolation of BR from the polymer solution and the drying and baling of BR at the end of the finishing process could be avoided. In addition, the preparation of BR solu-... 

Through polymerization of a styrene rubber solution, one obtains SB mass (styrene-butadiene). SB forms a twophase system in which the styrene is the continuous phase and the rubber, usually a butadiene base, is the discontinuous phase. The rubber phase also contains pockets of styrene. The SB polymer, because of its properties, is also known as impact resistant or high impact PS (HIPS). 

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