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Thermodynamic and Kinetic Study for Production of Micro and Nano Poly(Ethylene Terephthalate) Particles With Supercritical System

Oghazian, Farhad | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40656 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Goodarznia, Iraj
  7. Abstract:
  8. It is well known that poly(ethylene terephthalate) (PET) is a high melting compound which has exceptional value as a fiber and film-making material, and which currently dominates the whole field of linear polyester substances. However, the high viscosity and limited solubility in liquid solvents restrict its processing to powders and hence the range of applications of such a polymer. Traditionally, crushing, mechanical grinding, ball milling and precipitation from solution are methods for producing powders. The first three ones inevitably change the property of materials. The last one is carried out on the basis of the application of an anti-solvent to decrease the solubility of a material that is dissolved in solution, in which we must separate the product and the solution of solvent/anti-solvent that is always very difficult and expensive. The GAS process is based on the observation that the dissolution of a supercritical fluid in a liquid solvent is frequently accompanied by large expansion of the liquid phase. This causes the solution power of the solvent to reduce significantly and dissolved solute to precipitate. Therefore a major advantage of GAS over those based on conventional liquid anti-solvent is that, by a suitable choice of supercritical fluid and operating conditions, the solvent can be extracted by anti-solvent and removed completely leaving behind a dry precipitate. Moreover, the GAS process uses common organic solvents in which a variety of polymers can be dissolved at ambient temperature. This technique opens a bright future for producing new types of polymer materials because the powder shape, size distribution, morphology and the rate of precipitation can be controlled by temperature, pressure and the concentration of polymer in solvent. Both PET and CO2 are soluble in 2-chlorophenol, and the dissolved CO2 affects the solubility of PET in 2-chlorophenol. Thus it is expected that CO2 can be used as an anti-solvent to produce PET powder by GAS process. Our goals are, first, to understand the thermodynamic of the system and, second, study the kinetic of precipitated crystals and relating their morphology to operating conditions. The morphology of the precipitated PET was examined using scanning electron microscopy
  9. Keywords:
  10. Superfluid System ; Nanoparticles ; Gas Antisolvent Process ; Polyethylene Terephthalate ; Thermodynamic Study ; Kinetics Study

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