Critical temperatures and critical pressures of four thermally unstable substances，including butyl acrylate

methyl methacrylate

allyl acetone and allyl alcohol，were measured for the first time via the quick-flow method. In the process，a small amount of sample was heated up to critical state in a very short time as it was passing through a capillary glass tube.The variation relationships of apparent critical properties with residence time were determined and the critical properties data were subsequently obtained by means of extrapolation. Polymerization reaction and other side reactions during the heating up process were minimized thanks to the short residence time less than 12 seconds.Therefore

this method is fit for measuring critical temperature and critical pressure of thermally unstable substance. The reliability of experimental apparatus was verified with 1-heptene as the standard substance whose accurate critical properties can be referred to in literatures.