Use of a gas chromatograph for measurement of the rate of monomer desorption from poly (vinyl chloride) resins

Previous studies by a gravimetric technique have established that the sorption and desorption of small quantities of vinyl chloride monomer (VCM) by poly (vinyl chloride) (PVC) resin powders obeys Fickian diffusion kinetics. Consequently, the rate of sorption or desorption is very sensitive to the size and structure distribution of the resin particles and is a useful measure of these properties. To facilitate the measurement of desorption rates, an “inverse GC” technique has been developed, with the PVC powder taking the place of the usual gas Chromatograph column. The detector and electronics of the GC are used to follow the VCM content of a carrier gas stream passing through a PVC resin sample initially equilibrated to a uniform VCM content. This method yields results consistent with the gravimetric data and provides a convenient means of characterizing PVC particle structure.