Termination kinetics in free-radical bulk terpolymerization - the systems methyl acrylate - butyl acrylate - dodecyl acrylate and methyl methacrylate- butyl methacrylate - dodecyl methacrylate

Termination rate coefficients, k(t) for the terpolymerization of mixtures c ontaining the three acrylates: methyl, butyl, and dodecyl acrylate or the c orresponding members of the methacrylate family: methyl, butyl, and dodecyl methacrylate, have been measured via the single pulse (SP)-PLP technique. In the homopolymerization of each of the six monomers an initial plateau re gion of almost constant k(t) is seen which extends at least up to 15% and, for dodecyl acrylate and dodecyl methacrylate, even up to about 50% monomer conversion. Terpolymerization k(t) in this region of low and moderate conv ersion is remarkably well described by a rather simple correlation which ex clusively contains homopolymerization k(t) and the composition of the monom er mixture. This correlation turns out to be very useful for the modeling o f k(t) in mixtures of monomers that exhibit such an initial plateau region of k(t). For the systems under investigation, terpolymerization k(t) may be estimated within +/-30%. This finding is very remarkable in view of the en ormous differences in homopolymerization k(t) within each monomer family, e .g., k(t) of methyl acrylate exceeds the corresponding dodecyl acrylate val ue by a factor of 50 (or 5000%). The entire set of experiments has been car ried out at 40 degrees C and 1000 bar where the signal to noise ratio of th e laser-induced single pulse experiments is very satisfactory. No reason is seen why the conclusions about modeling of terpolymerization k(t) should n ot be valid at other reaction conditions including ambient pressure.