TY - JOUR
T1 - Surfactant Assisted Polymerization of Tetrafluoroethylene in Supercritical Carbon Dioxide with a Pilot Scale Batch Reactor.
AU - Galia, Alessandro
AU - Scialdone, Onofrio
AU - Filardo, Giuseppe
AU - Giaconia, Alberto
AU - Apostolo, Marco
PY - 2008
Y1 - 2008
N2 - Chain-free radical polymerization of tetrafluoroethylene (TFE) was carried out in supercritical carbon dioxide (scCO(2)), at 50 degrees C and 121-133 bar, with tertiary-amyl-per-pivalate as a free radical initiator, using a 5-L pilot scale batch reactor. Experiments were carried out both in the absence and in the presence of perfluoropolyether (PFPE) carboxylate surfactants. Stabilizers were employed under the free acid form and as sodium and calcium salts. An expanded fibrillated poly(TFE) was obtained in all experiments. In the case of surfactant-free polymerizations, the product was mainly constituted by irregular shape macroparticles having size in the range 200-500 pm. Quite interestingly, when the free acid surfactant was used, a clear acceleration of the polymerization rate was observed and smaller polymer particles with more regular quasi-spherical morphology were obtained. Melt fusion crystallinity of as-polymerized poly(TFE) seemed not substantially affected by the presence of the stabilizers and was rather high (80-86%) suggesting that polymerization mainly occurs at polymer particle surface. All these elements suggest that FLUOROLINK(R) 7004H PFPE carboxylic acid decreases coagulation of primary polymer particles leading to an increase in polymer surface area.
AB - Chain-free radical polymerization of tetrafluoroethylene (TFE) was carried out in supercritical carbon dioxide (scCO(2)), at 50 degrees C and 121-133 bar, with tertiary-amyl-per-pivalate as a free radical initiator, using a 5-L pilot scale batch reactor. Experiments were carried out both in the absence and in the presence of perfluoropolyether (PFPE) carboxylate surfactants. Stabilizers were employed under the free acid form and as sodium and calcium salts. An expanded fibrillated poly(TFE) was obtained in all experiments. In the case of surfactant-free polymerizations, the product was mainly constituted by irregular shape macroparticles having size in the range 200-500 pm. Quite interestingly, when the free acid surfactant was used, a clear acceleration of the polymerization rate was observed and smaller polymer particles with more regular quasi-spherical morphology were obtained. Melt fusion crystallinity of as-polymerized poly(TFE) seemed not substantially affected by the presence of the stabilizers and was rather high (80-86%) suggesting that polymerization mainly occurs at polymer particle surface. All these elements suggest that FLUOROLINK(R) 7004H PFPE carboxylic acid decreases coagulation of primary polymer particles leading to an increase in polymer surface area.
KW - membranes
KW - perfluoropolyether surfactant
KW - poly(tetrafluoroethylene)
KW - radical polymerization
KW - supercritical carbon dioxide
KW - surfactants
KW - membranes
KW - perfluoropolyether surfactant
KW - poly(tetrafluoroethylene)
KW - radical polymerization
KW - supercritical carbon dioxide
KW - surfactants
UR - http://hdl.handle.net/10447/13115
M3 - Article
VL - 46
SP - 257
EP - 266
JO - JOURNAL OF POLYMER SCIENCE. PART A, POLYMER CHEMISTRY
JF - JOURNAL OF POLYMER SCIENCE. PART A, POLYMER CHEMISTRY
SN - 0887-624X
ER -