GRAFT COPOLYMERIZATION BY A PREIRRADIATION METHOD
Free radioals as well as peroxides are formed when irradiation of polyethylene is accomplished with the use of cobalt-60 or a Van de Graaff electron accelerator, as radiation sources, even in the presence of air. The free radicals are able to induce graft copolymerization under low temperatures, in which peroxide grafting cannot occur. When the irradiated polymer is stored in air, the trapped free radicals disappear monomolecularly, probably combining with oxygen. The activation energy for this reaction is 20 kcal/mole. In graft copolymerization by free radicals, the per cent grafting is proportional to the square root of the free radical cortent, and the higher the grafting temperature, the faster the initial rate of graft copolymerization. There occurs a saturation phenomenon of the per cent grafting with a grafting time, especially in high temperatures, and the higher the grafting temperature, the smaller the saturation value. It is believed that the kinetic theory of vinyl polymerization in a homogeneous system is applicable for graft reaction in spite of its apparent heterogeneous character. (auth)
- Research Organization:
- Toyo Rayon Co. Ltd., Otsu, Japan
- NSA Number:
- NSA-14-017055
- OSTI ID:
- 4151839
- Journal Information:
- J. Polymer Sci., Journal Name: J. Polymer Sci. Vol. Vol: 44
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
AIR
COBALT 60
DECOMPOSITION
DISTRIBUTION
EFFICIENCY
ENERGY
FREE RADICALS
IRRADIATION
LOW TEMPERATURE
METALS, CERAMICS, AND OTHER MATERIALS
OXIDES
OXYGEN
POLYETHYLENES
POLYMERIZATION
POLYMERS
RADIATION SOURCES
REACTION KINETICS
SATURATION
STORAGE
TRAPS
VAN DE GRAAFF ACCELERATORS
VELOCITY
VINYL RADICALS