Search results for "Heterogeneous polymerization"
showing 2 items of 2 documents
Copolymerization of VDF and HFP in Supercritical Carbon Dioxide: A Robust Approach for Modeling Precipitation and Dispersion Kinetics
2012
A kinetic model is developed for the heterogeneous free-radical copolymerization of vinylidene fluoride and hexafluoropropylene in supercritical CO 2. The model accounts for polymerization in both the dispersed (polymer-rich) phase and in the continuous (polymer-free) supercritical phase, for radical interphase transport, diffusion limitations, and chain-length-dependent termination in the polymer-rich phase. A parameter evaluation strategy is developed and detailed to estimate most of the kinetic parameters a priori while minimizing their evaluation by direct fitting. The resulting model predictions compare favorably with the experimental results of conversion and MWD at varying monomer fe…
The rate of polymerization in two loci reaction systems: VDF-HFP precipitation copolymerization in supercritical carbon dioxide
2011
When the copolymerization of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) is carried out in supercritical carbon dioxide (scCO 2) under heterogeneous conditions, the reaction occurs both in the continuous CO 2-rich phase and in the dispersed polymer-rich phase. The two phases being characterized by different values of reactant concentrations and kinetic parameters, one would expect that the reaction kinetics is affected by the polymer phase holdup in the reactor. However, the reaction rate is almost insensitive to the amount of produced polymer, at least at specific reaction conditions. This apparent contradiction is discussed and clarified in this paper by a series of comparativ…