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The radical graft polymerization of vinyl monomers from carbon black initiated by azo groups introduced onto the surface was investigated. The introduction of azo groups onto the carbon black surface was achieved by three methods: (1) the reaction of 2,2'-azobis(2-cyanon-propanol) with acyl chloride groups on the surface, which were introduced by the reaction of carboxyl groups on the surface with thionyl chloride, (2) ihe reaction of 4,4'-azobis(4-cyanovaleric acid) with isocyanate groups on the surface, which were introduced by the treatment of carbon black with tolylene 2,4-diisocyanate, and (3) the reaction of hydroxyl groups on the surface with 4,4'-azobis(4-cyanovaleryl chloride). It was found that the polymerization of vinyl monomers such as methyl methacrylate and styrene was initiated by azo groups introduced onto the carbon black surface. During the polymerization, the corresponding polymer was effectively grafted onto the carbon black surface based on the propagation of the polymer from the radical produced on the surface by the decomposition of the azo groups. The percentage of grafting of poly(methyl methacrylate) and polystyrene using azo groups introduced by the method 2 increased to 40.0% and 28.5%, respectively. Furthermore, the effects of temperature and e-value of vinyl monomers on the graft polymerization were discussed. KEY WORDS Carbon Black / Graft Polymerization / Polymer-Grafted Carbon Black / Azo Groups / e-Value / 4,4'-Azobis(4-cyanovaleric acid) / Vinyl Monomer/ 2,2'-Azobis(2-cyano-n-propanol) /

Carbon blacks having tert-butyl peroxyester groups (1, 2, and 3) were prepared by the reaction of acyl chloride CB-COO -t-Bu II 0 CB-O-C(CH2) 4 ~-OO-t-Bu 0 2 yH3 CB-y-(CH2)i-~-OO-t-Bu CN 0 3 groups on carbon black with tert-butyl hydroperoxide. The introduction of acyl chloride groups onto carbon black was achieved by three methods: (I) reaction of a carboxyl group with thionyl chloride, (2) reaction of a phenolic hydroxyl group with adipoyl chloride, and (3) reaction of thionyl chloride with a carboxyl group introduced by the treatment of aromatic ring of carbon black with 4,4'-azobis(4-cyanovaleric acid). Carbon black 1 has no ability to initiate the graft polymerization of methyl methacrylate (MMA) because phenyl radical formed on the carbon black by decomposition of the peroxyester groups inhibited the polymerization. On the contrary, carbon blacks 2 and 3 were able to initiate the graft polymerization of MMA at 70-90°C and PMMA was effectively grafted onto the surface based on the propagation of the polymer from the alkyl radicals formed on the surface. The percentage of grafting of PMMA at 70°C by use of 3 as initiator increased to about 80% with progress of polymerization. Furthermore, the graft polymerization of several vinyl monomers initiated by 3 was investigated. KEY WORDS Carbon Black / Graft Polymerization / Polymer-Grafted Carbon Black / Peroxyester Groups / 4,4'-Azobis(4-cyanovaleric acid) / Methyl Methacrylate / tert-Butyl Hydroperoxide / 214 CB-R-fCH 2-CH1 CH 2-CH I n-I

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