Variation of the propagation rate coefficient with pressure and temperature in the free‐radical bulk polymerization of styrene

The propagation rate coefficient K p of the free‐radical bulk polymerization of styrene is determined between 30 and 90°C up to a maximum pressure of 2800 bar. The data from pulsedlaser polymerizations and product analyses by gel‐permeation chromatography (PLP‐GPC) are adequately represented by the expression: The conseaquences of deducing activation volumes and activation energies from k p /(L · mol −1 · s −1 ) or from k * p /(kg · mol ‐1 ·. S −1 ) are outlined.