Kinetics and mechanism of bulk polymerization of vinyl chloride

Investigation of the effect of delayed reflux on PVC grain properties produced by suspension polymerization

“…Several investigators have shown that molecular weight of the final PVC product slightly decreases with increasing initiator concentration 25, 27, 28. Molecular weight significantly depends on polymerization temperature and dominance of chain transfer to monomer reactions.…”

“…Several investigators have shown that molecular weight of the final PVC product slightly decreases with increasing initiator concentration. 25,27,28 Molecular weight significantly depends on polymerization temperature and dominance of chain transfer to monomer reactions. Xie et al 25 indicated that chain transfer to monomer reaction rate constant to propagation rate constant ratio (C M ) for conversions less than X f was constant, but C M in polymer rich phase was greater than that in the monomer rich phase.…”

Dynamic simulation of a PVC suspension reactor

“…In particular the parameter for precipitation seems to be out of bounds, requiring a critical chain length of about 3800 units. The following modifications of the Xie model have been made: l Simplification of the free volume theory for the termination and the propagation rate constant l Precipitation and desorption according Kuchanov [6] l Explicit initiator balances in both phases incorporating a finite mass transfer rate l Balance on primary polymer radicals incorporating the initiation step l A detailed reaction network and differential balance for polymer radicals This approach enables to examine directly the contribution of each elementary step and to modify it if necessary. The integration of approximately 250 differential equations plus the corresponding algebraic equations can be done with reasonable time in SPEEDUPm.…”

Enhancement of poly(vinyl chloride) productivity by continuous initiator injection

“…In the present study, a programmed initiator injection during the course of the polymerization is sought to attain a predefined K value for the product in shorter polymerization time relative to the commercial case where all the initiator is introduced into the reactor at the beginning of the polymerization. From 1968 through 1990, several mathematical models have been provided for polymerization of VCM . In these models, the diffusion‐controlled phenomena, which affect reaction rate and efficiency of initiators at high conversions, have not been accounted for.…”