RADIOCHEMICAL POLYMERIZATION OF SOME VINYL MONOMERS AT LOW TEMPERATURES (in French)
The radiochemical polymerization of acrylonitrile styrene and of methyl methacrylate was studied in solution in a polar solvent at low temperature and in the solid state. The kinetics of the polymerization of the styrene dissolved in ethyl bromide at low temperatures is analogous to that which has been observed previously in different chlorated solvents but it is different in several respects. This reaction is inhibited by oxygen and benzoquinone; the contribution of a radical mechanism to the total reaction seems more important in the case of the bromated solvent. The polymerization of the acrylonitrile in dimethylformamide geems to proceed by a radical mechanism even at - 78 deg . The irradiation of the methyl methacrylate in this same solvent at -78 deg gives practically no polymer. The radiochennical polymerization of solid acrylonitrile at - 196 deg is followed by a very marked post-polymerization. This re action is shown in particular when the irradiated mixture is reheated before the polymer is separated. A technique for following this post-polymerization during the reheating is given; this technique consists in a rapid melting of the reaction mixture at different periods after the end of the irradiation and a determination of the quantity of the polymer formed. The post-polymerization was also studied in the solid phase at constant temperature. The Arrhenius diagram of the initial velocity has a break near -140 deg . The total activation energy is 0.8 kcal/ mole between --83 and -- 140 deg . The effect of numerous additives is examined; all decrease the polymerization rate. The radiochemical polymerization of solid styrene follows kinetics analogous to that of acrylonitrile. There is a sharp acceleration during the passage from the liquid to the solid state. In the solid state the activation energy of the total reaction is 11.6 kcal/mole. Some additive s, such as nitrobenzene, o-dichlorobenzene, and hydroquinone, increase the reaction rate. Methyl methacrylate shows practically no polymerization when it is irradiated in the solid state. However, if some compounds with high viscosity, such as paraffin oil or castor oil, are added to the monomer, abundant polymerization is observed. The reaction was examined in detail in the case of mixtures of methyl methacrylate with paraffin oil. This system has a kinetic behavior analogous to that of acrylonitrile and of solid styrene. However, the conversion curves are accelerated with time. Iodine, benzoquinone, and oxygen inhibit the reaction. Beginning with the results of the present work and with literature data, the radiochemical yield of the initiation of polymerization in the solid phase was calculated. It was found that the G values (initiation centers) are found between 0.1 and 0.5 for the different systems examined, that is, they are of the same order of magnitude as the corresponding G values for ionic polymerizations and the G values (trapped radicals) in the solid monomers. (tr-auth)
- Research Organization:
- Centre National de la Recherche Scientifique, Bellevue
- NSA Number:
- NSA-16-029012
- OSTI ID:
- 4794098
- Journal Information:
- Journal de Chimie Physique (France) Merged with Rev. Gen. Colloides to form J. Chim. Phys. Rev. Gen. Colloides, Vol. Vol: 59; Other Information: Orig. Receipt Date: 31-DEC-62
- Country of Publication:
- Country unknown/Code not available
- Language:
- French
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Related Subjects
ACRYLIC ACID
AMIDES
BROMINATED HYDROCARBONS
CATALYSIS
CHLORINATED HYDROCARBONS
CYANIDES
DIAGRAMS
ETHYL RADICALS
EXCITATION
HEATING
IODINE
IRRADIATION
LATTICES
LOW TEMPERATURE
MELTING
METHACRYLATES
METHYL RADICALS
MIXING
OILS
ORGANIC NITROGEN COMPOUNDS
OXYGEN
PARAFFIN
PHASE DIAGRAMS
POLYMERIZATION
POLYMERS
QUANTITATIVE ANALYSIS
QUINONES
RADIOCHEMISTRY
REACTION KINETICS
SOLUTIONS
SOLVENTS
STYRENE
VELOCITY
VINYL RADICALS
VISCOSITY