Kinetics of styrene polymerization

A number of the mechanistic features proposed by Williams and Hayes were incorporated into a theoretical model developed by Denaro et al. to explain the kinetics of styrene polymerization in a 2 MHz discharge. Initiation was proposed to proceed through the collision of electrons with the polymer film... 

Investigation of kinetics of styrene polymerization was conducted the temperature interval of... 

The NIR-Raman spectroscopy was used by Wang et al. [163] to study the kinetics of styrene polymerizations in glass reaction flasks. Wang et al. [164], Ozpozan et al. [165], Al-Khanbashi et al. [166], Urlaub et al. [122], Bauer et al. [167], Van Den Brink et al. [168], McCaffery and Durant [169], and Elizalde et al. [170] performed similar studies forVA, styrene/butyl acrylate, MMA, cyanacrylate, styrene/ butadiene, styrene and butyl acrylate/MMA polymerizations in emulsion and miniemulsion reactions. These studies showed that NIR-Raman spectral data obtained in-line during emulsion polymerizations could be used for kinetic model building and kinetic analysis. 

Mechanisms. Because of its considerable industrial importance as well as its intrinsic interest, emulsion polymerization of vinyl acetate in the presence of surfactants has been extensively studied (75—77). The Smith-Ewart theory, which describes emulsion polymerization of monomers such as styrene, does not apply to vinyl acetate. Reasons for this are the substantial water solubiUty of vinyl acetate monomer, and the different reactivities of the vinyl acetate and styrene radicals the chain transfer to monomer is much higher for vinyl acetate. The kinetics of the polymerization of vinyl acetate has been studied and mechanisms have been proposed (78—82). 

Scanty though our information is, it indicates that most aromatic monomers show very similar kinetic behaviour under similar conditions. Moreover, it has recently been shown that the very simple kinetics of the polymerization of styrene by perchloric acid [27, 82] also apply to polymerization of p-chlorostyrene [83] by that catalyst. From concurrent studies of co-polymerization Brown and Pepper deduced that styrene gives a more reactive active species than p-chlorostyrene, and that styrene is the more reactive monomer. The former conclusion is not easily compatible with an ion being the chain-carrier. 

Fractional kinetic orders of homogenous reactions in solution may point to association of a particular reagent. The kinetics of the initiation step of styrene polymerization in the presence of n-BuLi (equation 33) is in accordance with the assumption that this organolithium compound in a nonbonding solvent forms aggregates of six molecules on the average" . 

Model 4. As a result Lam et al. concluded that Model 3 best describes the plasma polymerization kinetics of styrene. 

Kinetics of the propagation of styrene polymerization initiated by SrS2 in THF without added SrB2... 

Combining the kinetics of the polymerization and the electric conductivity measurements during the irradiation of bulk styrene (6), the... 

H. Hopff and N. Balint developed a copolymerization process for tetrachloroethylene with ethylene. Radiation-induced chlorination of polyisobutylene is the subject of the chapter of C. Schneider and P. Lopour. M. Litt, V. T. Stannett, and E. Vanzo show that the polymerization of vinyl caproate follows the kinetics of styrene. 

I. Kende and M. Azori Kinetics of inhibition of styrene polymerization by nitro compounds. IUPAC Symposium on Macromolecular Chemistry, Moscow 1960, Section II 31. 

Nomura (25) investigated the effect of carbon tetrabromide, carbon tetrachloride and long chain mercaptans on the kinetics of emulsion polymerization of styrene. In the case of CBr and CCl the effect on the polymerization was attributed to desorption of the small chain transferred radicals. Similar results were obtained by Napper et al (26). Nomura also observed that the long chain mercaptan (n- dodecyl mercaptan) did not affect the number of particles and the rate, presumably due to the water-insolubility of the chain transferred radicals. 

Table I. Kinetic Behavior of Styrene Polymerization Initiated by Radiation Under Wet (Radical) and Dry (Ionic) Conditions...

About thirty years ago, all cases of polymerization kinetics used to be solved as statinary reactions. Hayes and Pepper [27] were the first to call attention to the non-stationary character of ionic polymerizations. They noticed the premature decay of styrene polymerization initiated by H2S04 (see Fig. 8). This was a simple case of non-stationarity caused by the slow decay of rapidly generated active centres [27, 28]. They assumed that the polymerization proceeds according to a rather conventional scheme represented in simplified form (without transfer) by the reactions... 

The assumption of the significance of emulsifier adsorption capability to the kinetics of emulsion polymerization was suggested in our paper (6), for polar monomers, and by Roe (7) and Robb (8 for styrene. Paxton (2) demonstrated that the adsorption area occupied by a molecule of a given emulsifier (Ha-dodecyl benzyl sulphooate) on the surface of polymethylmethac-rylate latex particles, is 1.31 (nm), and so exceeds by a factor of 2.3 a similar area on the surface of polystyrene latex, equal to 0.33(n>n). ... 

Ballard and Van Lienden 16) showed that irradiation of Zr(CH2Ph)4 solutions in the presence of vinyl monomer increased the rate of thermal polymerization by a factor of four. Kinetic rate data suggested that the mechanism of styrene polymerization was wavelength dependent. For... 

In order to develop a sound optimization policy, a good understanding of styrene polymerization kinetics is necessary. In the following section the general kinetic scheme of styrene homopolymerization is introduced. 

A distinctive characteristic of styrene polymerization is its thermal selfinitiation at high temperatures (without the presence of a chemical initiator). The mechanism of styrene thermal initiation was first described by Mayo [12]. The kinetics of thermal initiation were described by Weickert and Thiele [13] as a second-order reaction, while Hui and Hamielec [14], Husain and Hamielec... 

In this review the polymerization of formaldehyde, h her aliphatic aldehydes and haloaldehydes will be discussed with particular emphasis on the kinetics of the polymerization. As will be apparent the kinetics of aldehyde polymerization have not been studied as extensively as the kinetics of more conventional polymerizations, for example, the free radical bond opening polymerizations of styrene, vinyl chloride or methylmethacrylate or the ring opening polymerizations of tetrahydro-furan or ethylene oxide. One reason is that polyoxymethylene is the only polyaldehyde produced commercially and much of our knowledge on formaldehyde polymerization is proprietary information. Another is that the polymerization systems are very complex and the polymers precipitate during polymerization. 

CUTTER and DREXLER Simulation of Styrene Polymerization Kinetics... 

Styrene is capable of forming moderately stable Co-C bonds.370 The formation and decomposition of adducts between the CCT catalysts and the propagating radicals results in reversible inhibition .123-271 In this case, an induction period is observed at the beginning of polymerization. This induction period is characterized by the steady growth of the rate of polymerization similar to the classic kinetics of a polymerization inhibited by a weak inhibitor. Depending upon conditions, the time required to reach steady-state polymerization kinetics (eq 42) may require tens of minutes. 

Higashimura and his co-workers have examined trifluoroacetic acid as an initiator of styrene polymerizations, and using n.m.r. spectra clearly identified a polystyryl or styryl ester (4). Equally clear from the kinetic data was that this species is not capable of propagating. 

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