Author
Abstract
Methoxy – oxo - bis [N - (4-bromophenyl ) Salicylidene – iminato ] Vanadium (V) : [VO (Br C6 H4 N : C H O C6 H4 )2 OCH3 can initiate methylmethacrylate thermally at 80°C . Under the experimental conditions employed, no retardation or inhibition is observed. The order with respect to the initiator concentration is (0.5), while the order with respect to monomer concentration is (1.8) which gives an indication that the rate of initiation is dependent on monomer concentration.
Spectroscopic studies suggest that during the thermal polymerization a reduction in the oxidation state of vanadium occurs with heterolytic scission of the V- OCH3 bond and this might be induced by MMA molecule which forms intermediate complex between VOL2 OCH3 and methyl methacrylate monomer before the formation of the primary radical responsible for the initiation process.
Activation energies of polymerization as well as initiation processes in the present system were also determined . The tacticity of polymer produced is examined.
According to the experimental results obtained a mechanism of thermal initiation reaction is proposed.
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