Polymer Processing in Supercritical Carbon Dioxide

Furthermore, many thanks are due to our collaborators in the Process Development Group in Eindhoven and the Polymer Reaction Engineering Group in Lausanne for their creativeness and enthusiasm in the field of polymer science in supercritical carbon dioxide. Finally, we would like to thank Karin Sora and her team from Wiley-VGH for their great help in producing this book. 

Woods, H.M., et al.. Materials processing in supercritical carbon dioxide surfactants, polymers and biomaterials. Journal of Materials Chemistry, 2004.14(11) p. 1663-1678. 

Merz, L. and Muth, O. (1996) Solubility, extraction and modification of polymers and polymer additives in supercritical carbon dioxide. Process Technol Proc. 12,373-78. Rindfleisch, F., DiNoia, T. and McHugh, M. (1996) Solubility of Polymers and Copolymers in Supercritical C02, J. Phys. Chem. 38, 15581-87. 

Chang, Y. W., Lee, D., and Bae, S. Y, 2006. Preparation of polyethylene-octene elastomer/ clay nanocomposite and microcellular foam processed in supercritical carbon dioxide. Polymer International 55 184-9. 

Arora K A, Lesser A J and McCarthy T J, Compressive Behaviour of Microcellular Polystyrene Foams Processed in Supercritical Carbon Dioxide , Polym. Eng. Sci., 1998, 38, 2055). 

Enantio-controUed processes have been developed [177] polymer-supported [178] FARs and other related systems such as PhCF2—NMc2 have also been studied [179], and reactions in supercritical carbon dioxide have been reported [180]. 

In our laboratory, we have reported the direct conversion of soybean oils in supercritical carbon dioxide to polymers with lower molecular weights (28). The resulting polymers could be used as lubricants and hydraulic fluids. The advantages of these polymers are their availability from a renewable resource, their biodegradability and their green processing method. Here, we discuss the synthesis and characterization of the resulting polymers from soybean oils. 

In Table 1.1, the critical properties of some compounds which are commonly used as supercritical fluids are shown. Of these, carbon dioxide and water are the most frequently used in a wide range of applications. The production of polyethylene in supercritical propane is described in a loop reactor [13]. Supercritical ethylene and propylene are also apphed, where they usually act both as a solvent and as the reacting monomer. In the field of polymer processing, the Dow Chemical Company has developed a process in which carbon dioxide is used to replace chlorofluorocarbon as the blowing agent in the manufacture of polystyrene foam sheet [14, 15]. 

The interest in C02-based processes has strongly increased over the past decades. Fig. 1.3 shows the number of papers and patents that have been published over the years concerning polymerizations in supercritical carbon dioxide (SCCO2). In the last ten years, a substantial rise in publications can be observed, which illustrates the increasing interest in SCCO2 technology for polymer processes. 

Typically, this process allows forming particles from a great variety of substances that need not be soluble in supercritical carbon dioxide, especially from some polymers that absorb a large concentration (10-40 wt.%) of CO2 [8]. This process can also be performed with suspensions of active substrates in a polymer or other carrier substance leading to composite microspheres. 

Liu et al. reported improved process for synthesizing fluorinated polymers in supercritical carbon dioxide [177]. The improvement consisted of modifying the reaction system and designing and using sampling tubes. 

The present chapter covers information published by resin manufacturers about the commercially available grades of melt processible fluoropolymers. The first two polymers are perfiuorinated resins, followed by partially fluorinated polymers ethylene-tetrafiuoro-ethylene and ethylene chlorotrifiuoroethylene, andpoly-vinylidene fluoride and polyvinylfiuoride, and finally concluding with fluoroplastics polymerized in supercritical carbon dioxide. Commercially available resins have been classified by type, grade, and manufacturer. Properties of commercial grades have been presented in this chapter based on the literature published by the manufacturers. 

NGO, T. T. V., Duchet-Rumeau, J., Whittaker, A. K., and Gerard, J. F., 2010. Processing of nanocomposite foams in supercritical carbon dioxide. Part 1 Effect of surfactant. Polymer 51 3436-44. 

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