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Cross radiation-induced

Radiation-induced degradation reactions are in direct opposition to cross-linking or curing processes, in that the average molecular weight of the preformed polymer decreases because of chain scission and without any subsequent... [Pg.424]

Radiation-induced modification or processing of a polymer is a relatively sophisticated method than conventional thermal and chemical processes. The radiation-induced changes in polymer materials such as plastics or elastomers provide some desirable combinations of physical and chemical properties in the end product. Radiation can be applied to various industrial processes involving polymerization, cross-linking, graft copolymerization, curing of paints and coatings, etc. [Pg.861]

The rate of 7-radiation-induced cross-linking in the crystalline and amorphous regions of a crystallizable polychloroprene has been measured by Makhlis et al. [75] who have found a considerably lower cross-link density and less degradation in the crystalline portion of the rubber. The cross-links have been posmlated to be mainly intramolecular in crystalline regions and intermolecular in the amorphous phases. [Pg.863]

Radiation-induced cross-linking of chlorinated and chlorosulfonated high-density PE has been reported by Korolev et al. [262]. It has been observed that the extent of cross-linking is strongly dependent on the chlorine content in the sample, chlorosulfonated PE is cross-linked more readily than the chlorinated sample in air and inert atmosphere. [Pg.876]

Radiation synthesis has been reviewed by Wagner (1969), Vershchinskii (1972), Wilson (1972), and Chutny and Kucera (1974). A good summary is also available in Spinks and Woods (1990). On the theoretical side, radiation-induced reactions of importance to industry can be classified as addition reactions, sub-sitution reactions, and other reactions including polymerization, cross-linking,... [Pg.367]

Acceleration of Radiation-Induced Cross-Linking of Polyethylene by Chlorotrifluoroethylene... [Pg.307]

In the previous papers, we reported that the radiation-induced cross-linking of polyethylene was accelerated by acetylene (4) and by the mixtures of acetylene and some fluorine-containing monomers (5). [Pg.307]

Procedure. The radiation-induced cross-linking was carried out as follows. About 0.1 g of polyethylene film was placed in a glass ampoule of 30 mm diameter and 200 mm long. Gaseous CTFE and the mixture of CTFE/butadiene was introduced into the ampoule under the gas pressure of 1 atm. after evacuation of the ampoule. The ampoule was irradiated by Y-ray with a cobalt-60 at the dose rate of 0.05Mrad/hr at room temperature. [Pg.308]

Role of Unsaturated Group in the Cross-Linking in the Presence of CTFE. In order to make clear the role of unsaturated group contained in polyethylene, the radiation-induced cross-linkings of the polyethylenes containing various concentrations of the unsaturated groups were carried out in the presence of CTFE. [Pg.309]

Radiation-induced cross-linking of LDPE in the presence of various fluorine-containing monomers at a dose of 2.5 Mrad... [Pg.310]

Radiation-Induced Cross-Linking in the Presence of CTFE/Butadiene Mixture. On the basis of the results mentioned in the previous section, it is concluded that in the irradiation of polyethylenes in the presence of CTFE the polyethylenes are mainly cross-linked through the addition reaction of the unsaturated groups contained in the main and the side chains of the polymers to the propagating graft chain radical of CTFE. Therefore, the radiation-induced cross-linking of polyethylene is expected to be accelerated by the presence of the mixture of CTFE and a diene monomer effectively than the presence of pure CTFE. [Pg.316]

The radiation-induced cross-linking of polyethylenes in the presence of CTFE/butadiene mixture with various compositions are shown in Figure 6. The overall degree of co-grafting decreased gradually with the increase in the mole fraction of butadiene in the mixture, while the gel fraction of the polymer was increased rapidly by the addition of a small amount of butadiene to CTFE and then decreased with the increase in butadiene mole fraction in the mixture. The maximum of the gel fraction was found at about 0.1-0.2 of butadiene mole fraction in the mixture. [Pg.316]


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See also in sourсe #XX -- [ Pg.200 ]




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