Analysis of the molecular weight distribution of polystyrene

In this paper are reported molecular weight distributions (MWD) of polystyrenes obtained by bulk free-radical polymerization of styrene under isothermal conditions. MWD of polystyrenes were determined by gel-permeation chromatography. From analysis of the results it is apparent that samples synthesized at 80 degreesC and 90 degreesC have a bimodal MWD whereas those obtained at 100 degreesC and 110 degreesC have unimodal MWD. By two-peak deconvolution of experimental curves (at 80 degreesC and 90 degreesC) it is possible to separate the contribution of polystyrene obtained before and after onset of the gel effect.