POLYMERIZATION OF /cap alpha/-METHYLSTYRENE BY ELECTRON IRRADIATION (in German)
Ampoules of alpha -methylstyrene sealed under vacuum were irradiated with 1-Mev electrons in a type JS Van de Graaff generator; comparative experiments with gamma rays were carried out with a /sup 60/Co source of 3000 deg C. High doses of electrons (ca. 10/sup 8/ rad) are necessary for polymerization. The conversion is graphed as a function of dose at 0 deg C; it reaches a maximum plateau of 65% at 4 x 10/sup 8/ rad; this may point to radiolysis of the polymer at doses above this. Polymerization conversion increases with decreasing dose rate, when dose and temperature are held constant; and conversion increases with decreasing temperature (22% at --22 deg C; 10% at 15 deg C; <1% at 60 deg C), as has been found with gamma rays. In the solid state between --40 deg C and --80 deg C the maximum yield is only about 5%. The molecular weights of all poly- alpha -methylstyrenes thus formed lie between 3000 and 12,000, independently of dose rate and temperature. All polymethylstyrenes formed in the liquid state have approximately the same tacticity independent of temperature (isotactic about 20%; syndiotactic about 80%). This corresponds to the tacticity of polymers formed cationically with Lewis acids. In the solid state the tacticity is: isotactic 38%, syndiotactic, 62%, comparable with the tacticity of anionic polymerization. In the liquid state the tacticity and the sensitivity towards water indicate a cationic mechanism for the reaction. NMR studies also indicate a cationic mechanism. (BBB)
- Research Organization:
- Deutsches Kunststoff-Institut, Darmstadt, Ger.
- NSA Number:
- NSA-18-020070
- OSTI ID:
- 4019016
- Journal Information:
- Kolloid-Zeitschrift (West Germany), Vol. Vol: 194; Other Information: Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- Country unknown/Code not available
- Language:
- German
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Related Subjects
CATIONS
COBALT 60
ELECTRON BEAMS
ENERGY RANGE
GAMMA RADIATION
IRRADIATION
LOW TEMPERATURE
METHYL RADICALS
MEV RANGE
MOLECULES
NUCLEAR MAGNETIC RESONANCE
POLYMERIZATION
POLYSTYRENE
RADIATION CHEMISTRY
RADIATION DOSES
REACTION KINETICS
SOLIDS
STYRENE
TEMPERATURE
VAN DE GRAAFF ACCELERATORS
WEIGHT