SYNTHESIS OF GRAFTED COPOLYMERS BEGINNING WITH POLYMERS BEING EXPOSED TO IONIZING RADIATION. I. GENERAL CHARACTERISTICS OF THE GRAFTING REACTION ON THE PREIRRADIATED POLYETHYLENE

Journal Article · Sun Jun 01 04:00:00 EDT 1958 · J. Polymer Sci.

DOI:https://doi.org/10.1002/pol.1958.1202912001· OSTI ID:4324783

Chapiro, A

When polyethylene is irradiated in the presence of air, peroxydic crosslinks are formed besides the formation of polymeric networks. These peroxydic crosslinks were uscd for preparing graft copolymers. Previously irradiated polyethylene sheets were heated at different temperatures in a vinyl monomer (acrylonitrile, methyl methacrylate, vinylcarbazole). It was stated that in these conditions the sheets grow in the reaction medium at very high grafting yields (corresponding to a final weight exceeding by a hundred times the initial weight). During this growth, the external shape of the sheets was maintained. The kinetics of these reactions at temperatures between 25 and 192 d was studied. The activation energy varied with the grafting temperature. For grafting acrylonitrile E = 9.3 kcal was found above 109 d and 17.4 kcal below that temperature, while for methyl methacrylate ihe values were, respectively, equal to 8.6 and 16.2 kcal above and below 9 d . This phenomenon was interpretated by observing that below 100 to 110 d the polyethylene contains crystallines zones which oppose the free diffusion of the monomer; as a result, a temperature depending term must be considered, corresponding to the activation energy of diffusion. Above 110 d C the crystallites are entirely melted and the monomer diffuses freely in the amorphous polymer. At 25 d the grafting is extremely low. This permits stocking of the polymer during very long periods (about one year) without any appreciable decrease of activity toward grafting. (auth)

• Research Organization: Laboratoire de Chimie Physique, Paris
• NSA Number: NSA-12-013851
• OSTI ID: 4324783
• Journal Information: J. Polymer Sci., Journal Name: J. Polymer Sci. Vol. Vol: 29
• Country of Publication: Country unknown/Code not available
• Language: French

Related Subjects

ACRYLIC ACID
AIR
CARBAZOLES
CHEMICAL REACTIONS
CHEMISTRY
CONFIGURATION
CROSS-LINKING
CRYSTALS
CYANIDES
DIFFUSION
ENERGY
EXCITATION
GAMMA RADIATION
GRAFT POLYMERS
HEATING
IRRADIATION
MELTING
METHACRYLATES
METHYL RADICALS
MONOMERS
ORGANIC NITROGEN COMPOUNDS
OXIDES
PEROXIDES
POLYETHYLENES
POLYMERIZATION
POLYMERS
PREPARATION
RADIATION CHEMISTRY
REACTION KINETICS
SHEETS
TEMPERATURE
TESTING
VINYL RADICALS
X RADIATION