Propagation rate coefficients in free-radical homopolymerizations of butyl methacrylate and dodecyl methacrylate

Propagation rate coefficients (k(p)) for the homopolymerizations of butyl methacrylate (BMA) and dodecyl methacrylate (DMA) were determined by the pulsed laser polymerization (PLP)/size-exclusion chromatography (SEC) technique. At ambient pressure, the polymerizations of BMA and DMA were studied between -20 and 50 degrees C and between 9 and 60 degrees C, respectively. For DMA the pressure dependence of propagation rate has been measured up to 1500 bar. The propagation rate coefficients of three major methacrylates (MMA, BMA, DMA) are available over an extended pressure and temperature range. The k(p) data at identical pressure p and temperature T are close to each other and exhibit a very pronounced family-type behaviour with respect to both pressure and temperature dependence. The uncertainty of experimental data is estimated to be +/- 10 per cent. The imperfect knowledge of the Mark-Houwink coefficients may give rise to an increased error for the BMA and DMA data which should, however, stay below +/- 20 per cent.