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

Abstract

Termination rate coefficients, kt, for the terpolymerization of mixtures containing the three acrylates: methyl, butyl, and dodecyl acrylate or the corresponding 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 region of almost constant kt is seen which extends at least up to 15% and, for dodecyl acrylate and dodecyl methacrylate, even up to about 50% monomer conversion. Terpolymerization kt in this region of low and moderate conversion is remarkably well described by a rather simple correlation which exclusively contains homopolymerization kt and the composition of the monomer mixture. This correlation turns out to be very useful for the modeling of kt in mixtures of monomers that exhibit such an initial plateau region of kt. For the systems under investigation, terpolymerization kt, may be estimated within ±30%. This finding is very remarkable in view of the enormous differences in homopolymerization kt, within each monomer family, e.g., kt, of methyl acrylate exceeds the corresponding dodecyl acrylate value by a factor of 50 (or 5000%). The entire set of experiments has been carried out at 40 °C and 1000 bar where the signal to noise ratio of the laser-induced single pulse experiments is very satisfactory. No reason is seen why the conclusions about modeling of terpolymerization kt should not be valid at other reaction conditions including ambient pressure. © WILEY-VCH Verlag GmbH, D-69451 Weinheim 1999.