High temperature bulk copolymerization of butyl acrylate methyl methacrylate: Reactivity ratio estimation

In order to extend the validity of existing mechanistic polymerization mode ls, it is necessary to conduct experiments beyond typical temperature range s. Bulk copolymerizations of butyl acrylate/methyl methacrylate were perfor med over an expanded temperature range (60 to 140 degrees C) compared to mo st studies published to date which have focused on a more limited temperatu re range (60 to 80 degrees C). From the large amount of collected data, rea ctivity ratios were estimated at five different temperatures. The reactivit y ratios were estimated from low conversion copolymer composition data usin g the error-in-variables model method (EVM). The low conversion data were s ubsequently coupled with high conversion data and the reactivity ratios wer e reestimated using non-linear parameter estimation based on the integrated copolymer composition equation. Using all of the available data, temperatu re-dependent expressions were developed for the reactivity ratios. The copo lymer composition data conformed to the Mayo-Lewis kinetic model over the e ntire temperature range and departures from this model due to depropagation reactions, a concern at elevated temperatures, were not observed.