František Hrabák

Thermal decomposition of copolymers of styrene and halogenated monomers

Abstract Copolymers of 1,2,2,2-tetrachloroethyl esters of unsaturated acids and halogenated N-phenyl maleimides with styrene were pyrolyzed; volatile products were analyzed with a mass spectrometer combined with a gas chromatograph. Hydrogen halide and carbon dioxide in the volatile products were determined during the thermal decomposition of copolymers in glass ampoules; the acyl chloride groups were determined in the residues. The thermal decomposition of copolymers of tetrachloroethyl esters with styrene sets in at ca. 230° by the release of chloral from the copolymer and splitting of some of the CCl bonds in the copolymer. The decomposition of copolymers of styrene with halogenated N-phenyl maleimides starts above 300° by depolymerization of the polystyrene chain sections and by splitting of some of the carbon-halogen bonds. At 310 and 500° for copolymers of tetrachloroethyl esters and at 500° for halogenated N-phenyl maleimides, there is radical dehydrohalogenation of the copolymers, with depolymerization of polystyrene blocks and splitting of carbon-carbon bonds in the main chain.

Transfer to monomer in the polymerization of N-(3-dimethylaminophenyl) maleimide and N-(3-dimethylamino-6-methylphenyl) maleimide

Abstract The kinetics of the homopolymerizations of styrene, N -(3-dimethylaminophenyl) maleimide ( I ) and N -(3-dimethylamino-6-methylphenyl) maleimide ( II ) in benzene and dimethylformamide, and the molecular weights of the polymers were studied. N -(3-Dimethylaminophenyl) succinimide, regarded as a model for polymer I, did not affect the polymerization of styrene. The data indicate degradative transfer of polymer radicals to dimethylformamide and pronounced transfer to monomers I and II ( C M ≈ 0.06–0.07). The value of k p /k t 1 2 for II is 0.09 dm 3 2 mole − 1 2 s − 1 2 .

Thermogravimetric analysis and the flash-ignition and self-ignition temperatures of copolymers of styrene with halogenated monomers

Abstract The TGA method was used in studies of the thermal decomposition of copolymers of styrene with 1,2,2,2-tetrachloroethyl esters of acrylic and fumaric acids and with halogenated N-phenyl maleimides, and of homopolymers of halogenated monomers and mixtures of polystyrene with poly[N-2,4,6-trichlorophenyl)maleimide]. The flash-ignition and self-ignition temperatures of these polymers were determined using the Setchkin apparatus. The data thus obtained are used to discuss the effect of the structure of halogenated comonomers on the thermal stability of their copolymers with styrene and on the character of the thermogravimetric curves. The flash-ignition and self-ignition temperatures are compared with results for the thermal decomposition of copolymers and with their chemical composition.

Mass spectra of the β-diketone chelates of 1,6-dichloro-1,5-cyclooctadienerhodium

The mass spectra of a number of complexes of general formula XRhIL, where X is 1,3-propanedione substituted at positions 1 and 3 with CH3, C6H5, p-C6H4CH3, p-C6H4OCH3, p-C6H4Cl and p-C6H4NO2 groups respectively and L is 1,6-dichloro-1,5-cyclooctadiene, have been measured. The spectra were used to characterize the fragmentation patterns of the molecular ions of the complexes under investigation and to explain the character of the RhL bond in the molecular ion-radicals [XRhL] + and in the fragments [RhL]+. The molecular ion-radicals of all complexes decompose to yield the fragments X+ and [RhL]+, but not [RhX]+. The appearance potential values (AP) of the fragment [RhL]+ obtained from various [XRhL]+ ions appear to depend on the character of the 1,3-substituents in the ligand X. The difference in the AP values of [RhL]+ for the nth and first complex is identical with the difference in dissociation energies of the XRh bond in the complex [XRhL] and may be related to the rates of polymerization of chloroprene initiated with the complexes studied here.

Copolymerizations of N-arylmaleamic acids with styrene and butadiene

Abstract N-(3-Dimethylamino-6-methylphenyl)maleamic (I) and N-(2,4,6-trimethylphenyl)maleamic (II) acids were prepared; their radical copolymerizations with styrene and butadiene were investigated. The monomer reactivity ratios were determined and the Alfrey-Price copolymerization constants (e, Q) were calculated. The ratio of the average kinetic chain length to the number-average degree of polymerization indicates pronounced chain transfer to I and II. Inhibitors of radical polymerization stopped the copolymerizations of I and II with styrene but not those with butadiene.

The polymerizations of N-methyl-N-phenyl-2-aminoethyl methacrylate and 4-dimethylaminostyrene initiated with carboxylic acids

Abstract By using the copolymerizations of N -methyl-N-phenyl-2-aminoethyl methacrylate (I) and 4-dimethylaminostyrene (II) with styrene initiated with 2,2′-azoisobutyronitrile (AIBN) and with CCl 3 COOH, the copolymerization parameters and Alfrey-Price copolymerization constants e and Q were determined for I and II. The only product of polymerizations initiated with CCl 3 COOH and CH 3 COOH in mixtures of II with vinyl monomers was a homopolymer of II. The order of homopolymerization of II in benzene initiated with CCl 3 COOH at 50° was 0.99 with respect to [II] and 1.10 with respect to [CCl 3 COOH]; the temperature dependence of homopolymerization in the range 25–40° was 63 ± 5 kJ mol −1 . The rate of homopolymerization of II in solution in C 6 H 6 at 50° was virtually unaffected by inhibitors. In the polymerization initiated with carboxylic acids, the radical character of propagation centres was proved for I, but not for II.

Termination and transfer of the polymer chain to a maleimide derivative containing the azo group

Abstract The copolymerizations of N-(3-dimethylaminophenyl) maleimide (I) and 4-(2-chlorophenyl)azo-3-maleimido-N,N-dimethylaniline (II) with styrene were investigated; the copolymerization parameters of the pairs ( I + styrene ) and ( II + styrene ) and k p /k t 1 2 hr I at 50° were determined; chain transfer to the maleimide ring of I was proved. The homopolymerization of styrene in the presence of 4-(2-chlorophenyl)azo-succinimide-N,N-dimethylaniline (III) was used to determine the ratio of the rate constant for addition of the polystyrene radical to the azo group in III to kp for styrene.

The effect of solvents on the homopolymerization of 4-dimethylaminostyrene initiated with CCl3COOH

Abstract In the polymerization of 4-dimethylaminostyrene (DMAS) initiated with CCl3COOH in solvents possessing different electron-donor and electron-acceptor properties and relative permittivity (cr), the cr value of the solvent correlates well with the polymerization rate. The greatest increase of rate of polymerization in the homogeneous system was observed in nitrobenzene. In this solvent, characteristics of the polymerization of DMAS initiated with CCl3COOH were determined; differences between these characteristics and the rate equation for a similarly initiated polymerization of DMAS in benzene have been elucidated.

Binding of polymer molecules with tertiary amine groups by halogen-containing compounds

Abstract Soluble polymers and copolymers with bound tertiary amine groups react at room temperature with halogens and halogen compounds to give crosslinked systems. Crosslinking occurs in solution, emulsion and in polymer mixtures, in ultra-violet and visible light and in the dark.

Anomalies in the polymerization kinetics of 4-dimethylaminostyrene initiated with trichloracetic acid in nitrobenzene

Abstract The relative permittivities ( ϵ r 20 ) of 4-dimethylaminostyrene (I) and of 0.5–3.0 M solutions of N , N -dimethyl-4-toluidine (DMT) were measured in nitrobenzene (NB) and in a mixture of NB with diisopropyl ether (NB + E), the DMT solutions modelled those of I. An increase in [DMT] from 0.5 to 3.0 M caused a decrease in ϵ r 20 from 32.3 to 18.3 in NB, while only from 20.8 to 18.3 in (NB + E) at fixed [NB]. The great difference between the ϵ r 20 of 0.5 and 3.0 M DMT solutions in NB explains the previously observed drop in the percentage rate of polymerization ( R P ) of I, in NB initiated with CCl 3 COOH, with increasing [I] o . In (NB + E) mixture with fixed [NB], the percentage R P and the limiting viscosity number [ν] of polyl increase with increasing [I] o . The observed dependences of both R P (in Msec −1 ) and [ν] on [I] 0 confirm the validity of the suggested polymerization scheme for I initiated with CCl 3 COOH, and make possible determination of the characteristics of the elementary polymerization reactions.