By radical copolymerization, thermostable copolymers of N-(2-chlorophenyl)maleimide (ZCPMI), N-(3-chlorophenyl)maleimide (3CPMI) and N-(4-chlorophenyl)maleimide (4CPMI) with vinyl acetate were prepared. The values of reactivity ratios determined according to the Kelen-Tud6s method are: r2CPMI = 0,148 and rvA = 0,049; r3CpMI = 0,221 and rvA = 0,032; r&-pM, = 0,655 and rvA = 0,O. The position of the C1 atom in the phenyl ring of CPMI influences the copolymerization kinetics. 2CPMI exhibits the strongest tendency for cross propagation, 4CPMI has the highest ability for homopolymerization. Vinyl acetate in all the three systems forms inactive radicals. The thermostability of all three copolymers is higher than that of the vinyl acetate homopolymer and decreases in the order poly(3CPMI-co-VA) > poly(4-CPMI-co-VA) > poly(2CPMI-co-VA).CCC 0025-1 16)3/92/$05.00

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