THE SIGNIFICANCE OF TRANSFER-REACTIONS IN PULSED-LASER POLYMERIZATIONEXPERIMENTS

In this work simulation calculations are presented, which carefully an alyze pulse initiated polymerization experiments of butyl acrylate in bulk in an extended temperature range published in the recent literatu re. Taking into account entire data sets of experimental results, a mo del has been developed which describes the experiments using a single parameter set. Especially the inadequacies in experiments are also cap tured by the model, that occur evaluating propagation rate coefficient s using the pulsed laser polymerization technique at low laser repetit ion rates and elevated temperatures. Enhanced chain transfer to small species is identified to be responsible for these effects and transfer rate constants are derived from the simulations. The model is then us ed to test experimental strategies in order to expand the k(p) determi nation towards temperatures higher than 35 degrees C, the maximum temp erature for which k(p) values of butyl acrylate are available so far. Performing pulsed laser experiments at high laser repetition rates (20 0 Hz) and initial radical concentrations (1.10(-4) mol/L) should preve nt the formation of the characteristic structure in the molecular weig ht distribution to be suppressed by this competing process.