Supercritical carbon dioxide polymers

The displacing fluid may be steam, supercritical carbon dioxide, hydrocarbon miscible gases, nitrogen or solutions of surfactants or polymers instead of water. The VSE increases with lower mobility ratio values (253). A mobility ratio of 1.0 is considered optimum. The mobility of water is usually high relative to that of oil. Steam and oil-miscible gases such as supercritical carbon dioxide also exhibit even higher mobility ratios and consequent low volumetric sweep efficiencies. 

Wignall, G.D. (1999) Neutron scattering studies of polymers in supercritical carbon dioxide. Journal of Physics Condensed Matter, 11 (15), R157-R177. 

Cooper, A.I. (2000) Polymer synthesis and processing using supercritical carbon dioxide. Journal of Materials Chemistry,... 

Although numerous advantages are associated with the use of supercritical carbon dioxide (scC02) as an ecologically benign and user friendly reaction medium, systematic applications to metal-catalyzed processes are still rare. A notable exception is a recent report on the use of scC02 for the formation of industrially relevant polymers by ROMP and the eyelization of various dienes or enynes via RCM [7]. Both Schrock s molybdenum alkylidene complex 24 and the ruthe-... 

Takamoto T, Uyama H, Kobayashi S (2001) Lipase-catalyzed synthesis of aliphatic polyesters in supercritical carbon dioxide. e-Polymers no.004... 

Supercritical carbon dioxide has been used as a dispersing medium for the manufacture and processing of polymeric materials. The process allows for the synthesis of high molar mass acrylic polymers in the form of micrometer-sized particles with a narrow size distribution. This procedure represents an environmentally responsible alternative to aqueous and organic dispersing media for heterogeneous dispersion polymerizations (Fox, 1994). 

The high-pressure phase behavior of polymer-solvent-supercritical carbon dioxide systems was investigated experimentally The polymers used were poly(methyl methacrylate), polystyrene, polybutadiene, and poly(vinyl ethyl ether) at concentrations ranging from 5 to 10% in mixtures with toluene or tetrahydrofuran. The experiments were conducted for temperatures from 25 to 70°C and pressures up to 2200 psi in a high-pressure cell (Kiamos and Donohue, 1994). 

High-Pressure NMR of Polymers Dissolved in Supercritical Carbon Dioxide (Dardin et al., 1997)... 

Agricultural processing will still incorporate solvents. As an example, soybean flakes were extracted with supercritical carbon dioxide to produce a solvent-free, good-quality soybean oil. During the SFE process, volatile compounds were trapped on a porous polymer trap attached at the exhaust port of the SFE apparatus. The volatile profile obtained from the sorbent trap was found to be similar to the headspace profile from the SFE/soybean oil removed during the same extraction. In addition, crude soybean oil was heated in a stirred reactor and the volatiles, which were stripped by supercritical carbon dioxide in an attempt to improve oil properties, were collected on sorbent traps and analyzed by the above method for comparison. The described methodology permits the characterization of volatiles and semivolatUes in SEE soybean oil and can be used to monitor the extraction and quality of the resultant oil (Snyder and King, 1994). 

Suitable gases in the form of supercritical fluids represent clean solvents/ carriers, which neither leave residues nor impose an environmental load. A number of factors determine the solubility of polymers in supercritical carbon dioxides (SCCO2) and these are given in Table 3.1. 

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