Analysis of the molecular weight distribution in free radical polymerization: Modelling of the MWD from the analysis of experimental GPC curves

In this paper different techniques for the deconvolution of experimental ge l permeation chromatography (GPC) curves of polymers obtained from batch re actors are examined with the aim of improving the modelling of the polymeri zation process. The deconvolution of the GPC curves gives insight into the effects of diffusive phenomena on the values of the average molecular weigh ts ((M) over bar(n) and (M) over bar(w)) and the molecular weight distribut ion (MWD) of the polymer. Two methods, one based on a two-peak deconvolutio n and the other one based on a multi-peak deconvolution, are compared. The different characteristics and relative merits of the two methods are illust rated using several sets of experimental data. In conclusion, the first met hod is less accurate but allows a separation of the two contributions given by the chemical and diffusive control of the MWD; the second method has a sound theoretical background (confirms the prediction of the free volume th eory) and is potentially much superior but the results prove to be more sen sitive to the quality of the experimental part.