0000000000443091
AUTHOR
G Storti
Modeling Heterogeneous copolymerization of fluorinated monomers in scCO2
In recent years the use of supercritical carbon dioxide (scCO2) in polymer processing and reaction has emerged as a “green” alternative to replace both environmentally hazardous organic solvents and water, whose utilization involves the production of large amount of waste streams. Moreover, scCO2 is non-toxic, inexpensive, and often exhibits intense plasticizing effect on polymers. In this work, the copolymerization of fluorinated monomers in scCO2 is explored. Batch free-radical copolymerization reactions of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) have been carried out at temperature of 50 C and pressure of 400 bar using DEPDC as initiator and different amounts of stabilize…
ScCO2 as polymerization medium for high value polymers: two recent cases
In recent years the use of supercritical carbon dioxide (scCO2) in polymer processing and polymerization reactions has merged as a “green” alternative to replace both organic solvents, environmentally hazardous (VOCs), and water, which use involves the production of large amount of waste streams. ScCO2 is non-toxic, inexpensive, and often exhibits high solubility in polymer matrixes. Moreover, it causes polymer plasticization, thus favoring the diffusion of low MW species (monomers, initiators or additives) in the polymer phase. In this work, the use of scCO2 as polymerization medium for two different special polymers is discussed. Fluorinated copolymers mainly find application in environme…
Copolymerization of VDF and HFP in Supercritical Carbon Dioxide: A Robust Approach for Modeling Precipitation and Dispersion Kinetics
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…