Thermal polymerization of styrene

Hazer [20,25] reported on the reaction of a po]y(eth-ylene g]ycol)-based azoester with methacryloyl chloride in the presence of (CH3CH2)3N. In this reaction double bonds were attached to the chain ends of the poly(ester) thus obtaining a macroinimer. Being used for the thermal polymerization of styrene, the material formed an insoluble gel [20]. Probably, both the C=C double bonds and the azo bonds reacted in the course of the thermal treatment. The macroninimer in a later work [25] was used for thermally polymerizing poly(butadiene) thus leading to poly(ethylene glycol-/ -butadiene) block copolymers. 

The presence of stable free radicals in the resin was further suggested by the strong inhibiting effect of traces of this product on the thermal polymerization of styrene. 

Yu (13) simulated a periodically operated CSTR for the thermal polymerization of styrene and found the MWD to increase at low frequencies but all effects were damped out at higher frequencies because of the limited heat transfer which occurs relative to the thermal capacity of industrial scale reactors. 

Initial rates for the thermal polymerization of styrene in various... 

Table XII.—Thermal Polymerization of Styrene in Toluene at 100°C (Schulz, Dinglinger, and Husemann o)...

F. R. Mayo (private communication) has found evidence that thermal polymerization of styrene may actually be of a higher order than second, i.e., about five-halves order. This would suggest a termolecular initiation step. Generation of a pair of monoradicals in this manner, i.e., from three monomer molecules, would be acceptable from the standpoint of energy considerations. 

Fig. 21.—A comparison of the effects of 0.1 percent of benzo-quinone (curve II), 0.5 percent of nitrobenzene (curve III), and 0.2 percent of nitrosobenzene (curve IV) on the thermal polymerization of styrene at 100°C. Curve I represents the polymerization of pure styrene. (Results of Schulz. )...

The inhibitors more commonly used are molecules which in one way or another react with active chain radicals to yield product radicals of low reactivity. The classic example is benzoquinone. As little as 0.01 percent causes virtual total suppression of polymerization of styrene or other monomers. This is true of both thermal and initiated polymerizations. Results of Foord for the inhibition of thermal polymerization of styrene by benzoquinone are shown in Fig. 22. The... 

Fig. 22.—Inhibition of the thermal polymerization of styrene at 90°C by benzoquinone. The log of the viscosity relative to that of pure monomer is here used as a measure of polymerization. The small induction period in the absence of quinone presumably was caused by spurious inhibitors present in the monomer. (Results of Foord. )...

The effect of the nitrone stmcture on the kinetics of the styrene polymerization has been reported. Of all the nitrones tested, those of the C-PBN type (Fig. 2.29, family 4) are the most efficient regarding polymerization rate, control of molecular weight, and polydispersity. Electrophilic substitution of the phenyl group of PBN by either an electrodonor or an electroacceptor group has only a minor effect on the polymerization kinetics. The polymerization rate is not governed by the thermal polymerization of styrene but by the alkoxyamine formed in situ during the pre-reaction step. The initiation efficiency is, however, very low, consistent with a limited conversion of the nitrone into nitroxide or alkoxyamine. 

Some examples, such as thermal polymerization of styrene and decomposition of di-f-butyl peroxide, are given in [194], both treated as first-order reactions. The activation energy found for the decomposition of di-f-butyl peroxide agrees well with the literature value. From the pressure data, it appears that the initial pressure rise is caused by the evaporation of toluene, present as a solvent. At higher temperatures, the gases generated by decomposition are the main contributors to the pressure rise. 

Thermal Polymerization of Styrene in Bulk (Effect of Temperature)... 

A novel procedure [5] is exemplified in the preparation of polystyryl aluminium derivatives by thermal polymerization of styrene in the presence of AlEt3 acting as chain transfer agent. 

A number of other dimers are also formed in thermal polymerization of styrene. Two of these (35, 36) can be found as impurities of the highest concentration (up to 1%) in commercial polystyrene.226,227... 

As long as the concentration of the small molecule is low (<5%), the scattered intensity due to concentration fluctuations will be negligible relative to the density or anisotropy fluctuations. In polystyrene, the HV spectrum will not have any contribution due to concentration fluctuations, but in principle there could be a contribution due to the diluent anisotropy. The average relaxation time will be determined by the longest time processes and thus should reflect only the polymer fluctuations. The data were collected near the end of the thermal polymerization of styrene. Average relaxation times were determined as a function of elapsed time during the final stages of the reaction... 

Fig. 9. Average relaxation time for polystyrene plotted logarithmically against the elapsed time daring the final stages of the thermal polymerization of styrene...

Figure 10. Thermal polymerization of styrene-p-divinyl benzene at 70°C optimum for popcorn polymer formation...

Dinaburg, V. A., and A. A. Vansheidt Meicaptans and disulfides as chain transfer agents in thermal polymerization of styrene. Zhur. Obschei Khim. 24, 840 (1954). 

Variation with Temperature of the Number of Latex Particles formed in the Thermal Polymerization of Styrene emulsified with 4.6 x lQ-d mol dm Sodium dodecyl benzene sulfonate in 1.7 x 10 " mol dnT So dium sulfate"... 

Figure 1. Arrhenius plots of dependence of number of particles formed per cm3 water on temperature in the thermal polymerization of styrene emulsified with (I) potassium octadecanoate and (II) sodium dodecyl benzene sulfonate...

Figure 2. Particle size distribution for latex particles formed by thermal polymerization of styrene emulsified with potassium octadecanoate at 65°C...

For example, in table III, the temperature regimes of thermal polymerization of styrene are given, they allow to obtain polymer with Mn approximately at 1,5 10 and with various values of the ratio of... 

Stein, D. J., Mosthaf, H., Oligomer formation in the thermal polymerization of styrene, Angew. Makromol. Chem. 2 (1968) 39. 

S6). It depended on the variation of the number of latex particles formed iV with temperature. Unfortunately, they have overlooked the fact that the particle growth rate fi which appears to the power —f in the Smith-Ewart expression for the number of latex particles formed coitains the propa gation rate constant which is temperature dependent. It has also recently been realized that another factor on which JV depends, the area occupied by a surfactant molecule at the polymer-water interface Og, is also temperature dependent- Dunn et al. (1981) observed that the temperature dependence of N in the thermal polymerization of styrene differed from different emulsifiers. It seems unlikely that the differences ran be wholly explained by differing enthalpies of adsorption of the emulsifiers and, if not, this observation implies that the energy of activation for thermal initiation of styrene in emulsion depends on the emulsifier used. Participation of emulsifiers in thermal initiation (and probsbly also in initiation by oil-soluble initiators) is most probably attributable to transfer to emulsifier and desorption of the emulsifier radical frcan the micelle x>r latex particle into the aqueous phase the rates of these processes are likely to differ with the emulsifier. 

Continuous Bulk Thermal Polymerization of Styrene-Comparison of Computer Prediction With Experimental Data... 

The thermal polymerization of styrene (5), the alkali catalyzed polymerization of lactams (6) and (as some would have it)... 

The simplest examples of CB-A antioxidant are quinones, and benzoquinone has widely been used to inhibit alkyl-radical reactions (such as the thermal polymerization of styrene on storage). They react with polymer alkyl radicals (R-) formed on chain scission or through attack on the backbone to give the reduced form of the radical as shown in Scheme 1.65. 

Simon in 1839 named the distillate of Storax officinalis a styrol. By 1845, the thermal polymerization of styrene as well as the thermal depolymerization of PS were known. In 1915 I. G. Farbenindustrie started commercial production of PS, Trolitul . Until the 1950 s, PS was produced in small quantities — the resin was brittle, thermally unstable, with poor solvent and scratch resistance. The main use of styrene was in the manufacture of styrenics, viz. Buna-S, SBR, or ABS. 

Styrene is soluble in CH3OH but not in H2O. Precipitation with HjO will consequently bring down both the imreacted styrene monomer and polystyrene. No, attempting to distill off the monomer would probably initiate thermal polymerization of styrene. 

The average life time of the growing chain is short, bnt a chain of over 1000 iniits can be produced in 10 to 10 s. Bamford and Dewar have estimated that the thermal polymerization of styrene at 373 K leads to chains of x = 1650 in approximately 1.24 s, i.e., a monomer adds on once in every 0.75 ms. 

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