Thermal Bulk Polymerization Research Articles

BULK POLYMERIZATION OF STYRENE IN A STATIC MIXER

An experimental investigation of thermal bulk polymerization of styrene in a pilot plant will be reported. The plant is composed of a recycle tubular reactor followed by a tubular reactor. The conversion of the pre-polymerization part is in the range of 0 to 60% and at the outlet of the pilot plant up to 96%. Studies on the residence time distribution show plug-flow behaviour for a variety of different conditions with respect to viscosity and density gradient. The polymers obtained are characterized by gel permeation chromatography and compared to commercial products.

Le poly(α‐acétoxystyrène) et les copolymères de l'α‐acétoxystyrène avec le styrène et styrènes substitués obtenus par polymérisation thermique. Etude de la microstructure et de la stabilité thermique des polymères

AbstractThe microstructure of poly(α‐acetoxystyrene), prepared from α‐acetoxystyrene by bulk thermal polymerization, was studied by 1H and 13C NMR spectroscopy. Anomalies observed in the NMR spectra could be ascribed to fragmentations with formation of benzoxy and acetoxy radicals followed by re‐initiation. The thermal degradation of the polymer, resulting in the formation of polyphenylacetylene, rules out certain types of transfer. α‐Acetoxystyrene was copolymerized with styrene or substituted styrenes and the NMR study (1H and 13C) was limited to α‐acetoxystyrene. The composition of the copolymer could be ascertained by means of the resonances of the quaternary carbons of the aromatic cycle. The copolymers were characterized by viscometry, GPC, and thermal degradation. Their compositions, except that of poly(α‐acetoxystyrene‐co‐styrene) were determined by elemental analysis.

Polymerization of hexachlorocyclotriphosphazene by sulphur and selenium

The thermal bulk polymerization of hexachlorocyclotriphosphazine is described. The possibility of obtaining soluble polymer using sulphur and selenium as catalysts was investigated. It was found that the catalytic activity of selenium was much lower than that of sulphur. Monomeric sulphur may be acting as a chlorine-attractive agent for hexachlorocyclotriphosphazine.

Unsaturated oligoimides of cardic diamines and polymers based on them

The reaction between the dianhydride of 3,3′,4,4′-benzophenonetetracarboxylic or 3,3′,4,4′-diphenyloxidetetracarboxylic acid with an appropriate excess of a cardic diamine (9,9-bis-(4′-aminophenyl) fluorene, 9,9-bis-(4′-aminophenyl) anthrone-10, 3,3-bis-(4′-aminophenyl) phthalide or 3,3-bis-(4′-aminophenyl)phthalimide) has been used to synthesize oligoimides of cardic diamines with end acryl- or methacrylamide groups; the oligoimides are readily soluble in DMF, DMAA and tetrachlorethane and have various molecular masses and softening points of 210–310°C. It has been shown that the thermal stability of the unsaturated oligoimides increases as their degree of polymerization is increased. Crosslinked polyimides, characterized by high heat resistance and thermal stability, have been obtained by the thermal polymerization in bulk at 250–310°C of the oligoimides that have been synthesized.

Kinetics and Mechanism of the Bulk Thermal Polymerization of (3-Phenoxyphenyl)acetylene

Kinetics and Mechanism of the Bulk Thermal Polymerization of (3-Phenoxyphenyl)acetylene

Thermal polymerization of styrene

An experimental investigation of the kinetics of bulk thermal polymerization of styrene in the temperature range of 200°–230°C is reported. Conversions and molecular weight averages were measured by gel permeation chromatography. At elevated temperatures, oxygen in the polymerization mixture appears to have negligible effect on the rate of polymerization and the molecular weights of the polymer. Experimental evidence suggests that the molecular weight development of the polymer is strongly influenced by transfer reactions.

Differential method of treating chromatographic curves when analysing polymerization kinetics

A study was made of the treatment of chromatographic curves when analysing polymerization kinetics using PS samples obtained by thermal polymerization in bulk by different methods. The relative error of the method was evaluated. Possibilities offered by the method and advantages were shown when analysing MWD of polymers, in order to study kinetics and the reaction mechanism of polymerization at advanced stages of monomer conversion.

The kinetics of the trimethoxyboroxine‐induced thermal polymerization of phenyl glycidyl ether

AbstractThe kinetics of the bulk thermal polymerization of phenyl glycidyl ether induced by trimethoxyboroxine were investigated. Infrared absorption spectroscopy and gel permeation chromatography were used to follow the course of polymerization, while proton and boron‐11 NMR spectroscopy were used to support the kinetic model developed. The postulated mechanism involves a fast‐initiated, nonstationary cationic polymerization with five elementary steps, including spontaneous and monomer transfer as well as a termination reaction. The trimethoxyboroxine was found to be incorporated into the structure of the cured polymer. The polymerization was followed at several temperatures and with several ratios of initial concentrations of trimethoxyboroxine to phenyl glycidyl ether.

Direct detection of free radicals by EPR method during the polymerization of compounds of the acetylenic series

When the thermal bulk polymerizat ion of phenylacetylene, diphenylacetylene, p-iodophenylacetylene, phenoxyacetylene and diphenylbutadiyne (DPBD) is ca r r i edou t directly in an EPR spec t romete r at 150 o an intense EPR signal is observed immediately. In all cases , with the exception of DPBD, the EPR signal represen ts a single absorption line with a g factor that is close to the g factor of a free electron. In the polymerizat ion of DPBD the EPR signal has a hyperfine s t ruc ture (HFS) that consists of at least four lines, with a splitting of 35 Oe between the ext reme components. The two middle HFS lines are masked by an intense central signal, which has the same nature as the single absorption line in polyphenylacetylene, polydiphenylbutadiyne, and other polymers containing a conjugation system. Since the EPR signal disappears when the mater ia l is cooled to a t empera ture where the polymerizat ion of the corresponding monomer fails to occur , and the process is inhibited by N,N-diphenylpicrylhydrazyl , it may be assumed that we were the f i rs t to use the EPR method to direct ly detect the free radicals that take part in the polymerizat ion of c o m pounds of the acetylenic se r i es .

Thermal bulk polymerization of cholesteryl acrylate

AbstractThe thermal bulk polymerization of cholesteryl acrylate was carried out in the solid phase, the mesomorphic phase, and the liquid phase to study the effect of monomer ordering on polymerization rate and polymer properties. The rate increased with decreasing ordering (or enhanced mobility) of the monomer. Formation of inhibitive by‐products during the polymerization limited conversions to 35%. The sedimentation constant S0 = 6.2 S was the same for the polymers obtained in the three phases. The weight‐average molecular weight (M̄w) was 480,000 as determined by ultracentrifugation. Poly‐(cholesteryl acrylate) formed in bulk is randomly coiled when dissolved in tetrahydrofuran. The thermal properties of the monomer are given.

The properties of nuclear brominated styrenes I—The synthesis and polymerization of dibromostyrene and tribromostyrene

Mixtures of 2,4- and 3,4-dibromostyrene have been prepared by two synthetic routes. The rate of polymerization observed in the absence of solvents and chain transfer agents showed a marked acceleration from very low conversion, and insoluble polymer was obtained. The acceleration in rate of the bulk polymerization has been attributed to a Trommsdorf effect, and the formation of insoluble polymer to crosslinking by chain transfer to monomer and polymer. The new monomer 2,4,5-tribromostyrene has also been prepared and characterized. The following order of rates of thermal polymerization has been established in solution:2,4,5-tribromostyrene > 2,4- and 3,4-dibromostyrene ⪢ styreneAn insoluble polymer was also obtained from the bulk thermal polymerization of 2,4,5-tribomostyrene.

Polymerization of Chloroprene II. Role of Dimers in Thermal Polymerization

Abstract The results in this paper indicate that the bulk thermal polymerization of chloroprene at 35° is in fact a polymerization of chloroprene dimers, and the rate measurements indicate that little or no monomer adds during the propagation process. Since DPPH does not inhibit the dimerization process but inhibits polymerization, it is tempting to conclude that the polymerization is a free-radical addition process, and this idea is to some extent supported by the retarding influence of some other free-radical inhibitors. On the other hand certain features of the polymerization of bulk dimers are difficult to reconcile with a simple free-radical chain mechanism, and it is considered that it would be premature to postulate such a process. It seems likely that monomer participates in the initiation of chains, but there is no unambiguous evidence to suggest how this process might occur. In view of these problems a detailed discussion of possible reactions is hardly relevant at the present stage, and this must await the results of future experimental work.

A comparative study of the kinetics of thermal bulk polymerization of styrene by the viscometric and dilatometric methods

In studies of the effect of colloidal platinum and gold on the kinetics of the early stages of the bulk polymerization of styrene [1, 2] the viscometric method of Bamford and Dewar [3] was used for estimating the rate of polymerization. On the assumption that in the initial stages of retarded polymerization the intrinsic viscosity [η] of the polymer is approximately constant we used dη sp/ dt = [ η] dc/ dt, as a measure of the rate, because at low values of c the equation η sp = [ η] c is applicable. Meanwhile direct measurement of the rate of thermal polymerization of styrene in bulk by the dilatometric method shows that in the initial stages the rate is constant and the reaction corresponds to zero-order kinetics. By comparison of this result with the equation of Bamford and Dewar it is not difficult to reach the conclusion that under normal polymerization conditions dη sp/ dt and [η] must be time dependent and that their time relationships should be independent. This leads to the need for a more detailed study of the limits of applicability of the viscometric method, and particularly elucidation of the problem of whether the quantity dη sp/ dt can serve as a measure of the rate (i.e. whether it is proportional to the rate) under the conditions of unretarded polymerization.

The Microstructure of Diene Polymers. I. Polyisoprenes and Polybutadienes Prepared at High Temperatures

Abstract In a previous paper a method has been described by which the microstructure of synthetic polyisoprenes can be deduced from intensity measurements in the infrared spectrum of these polymers. Similar analyses have been made in the case of polybutadienes by Hart and Meyer and by Hampton. It is the purpose of the present paper to present the results of structural determinations on polyisoprenes and polybutadienes prepared by bulk thermal polymerization in the temperature range 100 to 250° C.

The microstructure of diene polymers. I. Polyisoprenes and polybutadienes prepared at high temperatures

AbstractPolybutadienes and polyisoprenes prepared by bulk thermal polymerization at temperatures between 100 and 250°C. have been analyzed for the percentages of the various types of addition present. It is found that polybutadiene tends toward a mixture of about 40% each of cis‐1,4‐ and trans‐1,4‐ and 20% 1,2‐addition as the polymerization temperature is increased. Polyisoprenes show a decrease of 1,2‐addition and cis‐1,4‐addition and a corresponding increase in trans‐1,4‐ and 3,4‐addition at preparation temperatures above about 100°C. Differences in energy and entropy of activation for the formation of the various structures in polybutadiene are given.