Polymerization polystyrene

Vinyl polymers cross-linked with divinyl monomers, for example, polystyrene polymerized in the presence of divinyl benzene. 

The first living polymer studied in detail was polystyrene polymerized with sodium naphthalenide in tetrahydrofuran at low temperatures ... 

Say that at c = 1 mM the propagation rate is not affected by the addition of TMEDA, a reasonable assumption based on the data of Helary and Fontanille. This leads to ktKigs = 0.84 10-2 M1/2 sec-1 as derived from the equation c = k2Kdiss/8k, whereas its value determined from the kinetics of lithium polystyrene polymerization in cyclohexane is 0.7 102 M1/2 sec-1. The agreement is fair. Note, the results are independent of the value of Kso). 

The kinetics of lithium polystyrene polymerization obeys a first order law at constant concentration of TMTCT. The first order constant increases linearly with the concentration of this complexing agent149) and becomes constant for [TMTCT] [lithium polystyrene] as shown in Fig. 23. 

Polymerization is the formation of large molecules (polymers) by the bonding together of many smaller molecules. For example, styrene polymerizes to form polystyrene. Polymerization can enhance the tendency of a substance to be adsorbed on mineral surfaces by increasing the molecular weight, but is not likely to result in detoxification of hazardous wastes. 

G. F. D Alelio invention of sulfonated polystyrene polymerization cation exchangers. 1942... 

C. H. McBurney Invention of aminated polystyrene polymerization anion exchangers. 1947... 

Ethylbenzene is commonly used as a solvent diluent during the polystyrene polymerization process. It can be found in the finished material and can be a source of taints as well. As seen in Table 14-2 the sensory taste threshold concentrations for ethylbenzene are 2 to 3 times higher than those for styrene. 

Figure 1. Linear dependence of the observed propagation constant, kD, of living polystyrene polymerization on [living polymers] 11 for Li+y Na+, K+, Rb+, and Cs+ salts in THF at 25°C.

Derive an expression for the polydispersity found in a linear polycondensation of equimolar amounts of A-A- and B-B-type monomers. What is the limiting value How does this limiting compare to that calculated for a free radical polymerization Explain why the polydispersity of a sample of (say) polystyrene polymerized to a high degree of conversion differs from this. 

Bulk polymerization is the main process for making high-impact polystyrene (HIPS). Polybutadiene is dissolved in styrene at 3-10% (w/w) concentration and the styrene is polymerized with careful agitation. Phase separation occurs with polybutadiene-g-polystyrene separating out. The final product is a dispersion of polybutadiene particles, which themselves contain occluded polystyrene. Polymerization conditions are adjusted to control the size and volume of these particles, which range respectively from 0.1 to 6.0 pm and 0.1 to 0.4 volume fraction of the material. 

Another mechanism for polystyrene polymerization (Mayo ) involves a regio-selective (4 + 2) Diels Alder adduct which rapidly undergoes hydrogen abstraction (molecular assisted homolysis) by another... 

Dialkyl peroxides Polyethylene cross-Unking Initiator for polystyrene polymerization Polypropylene rheology modification... 

Diacyl peroxides Initiator for polystyrene polymerization Unsaturated polyester curing... 

Industrially manufactured polystyrene, polymerized with radical initiators, exists mainly as the atactic polymer. The IR spectrum of this form of polystyrene features bands consistent of a mono-substituted aromatic compound. In addition to the normal aromatic absorptions, such as the C—H stretching between 3110 and 3000 cm , and the characteristic ring vibrations at approximately 1600 and 1500 cm (1601 and 1493 cm for polystyrene), the spectrum also contains the combination bands characteristic of monosubstitution (at 1942, 1868, 1802, and 1741 cm ), and the out-of-plane C —H ring deformations for monosubstitution (757, 699, and 541 cm ). Note that the C—H stretching reflects the alternating methylene... 

The polystyrene polymerization process uses styrene as a monomer. As such, the diffusivity of styrene in polystyrene is an important property. Find a value of such a diffusivity at 200°C. 

A -Hydroxyco(polystyrene Polymeric active ester for Rogozhin et al., 1973... 

Apicella, A., lannelli, P., Nicodemo, L., Nicolais, L., Roviello, A., and Sirigu, A., Dimensional stability of polystyrene/polymeric liquid crystal blends, Poiym. Eng. Sci. 26 600 (1986). 

An examination of the theory reveals this to be a minimum value, since it assumes that the polystyrene was fully crosslinked at the time of phase separation. Separate studies (7) reveal that polystyrene polymerized linearly under similar conditions has an M =... 

Newman, T. H., Malanga, M. T. Syndiotactic polystyrene polymerization results using a titanium(III) complex, CpTi(OMe)2 and imphcations to the mechanism of polymerization./. Macromol. ScL-PureAppl. Chem.A, M, 1921 (1997). 

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