Supercritical fluid extraction and determination of plastics additives.
Item
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Title
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Supercritical fluid extraction and determination of plastics additives.
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Identifier
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AAI9207140
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identifier
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9207140
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Creator
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Wolfe, Evelyn A.
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Contributor
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Adviser: David Locke
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Date
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1991
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Analytical | Chemistry, Polymer
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Abstract
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Supercritical Fluid Extraction (SFE) has been evaluated as an efficient technique for the quantitative extraction of plastics additives such as antioxidants and UV absorbers from polypropylene. The method is successful in providing a rapid, clean and quantitative extraction that takes no longer than 30 min. and suffers no problems of prolonged sample exposure to light, air, elevated temperature or reactive solvents. Gram samples of polypropylene containing Irganox 1010, Irgafos 168 and Irganox 3114 are extracted with supercritical carbon dioxide in a closed system for 15-30 min. at pressures between 8000-9000 psi and temperatures in the 60-90{dollar}\sp\circ{dollar}C range. Depressurization of the extract-laden CO{dollar}\sb2{dollar} across a trap packed with either silica or Chromosorb W causes deposition of the additive. It is then eluted from the trap with a small volume of methylene chloride and analyzed by HPLC with UV detection. No further cleanup was necessary. Recovery is studied as a function of pressure (density), temperature, time and plastic particle size. Recovery generally increases with density, time, temperature and decreased particle size, asymptotically approaching 100%. Irganox 245, Irganox 1076, Tinuvin P and Tinuvin 327 spiked onto pure polypropylene give recoveries between 70-96%. The solubility of these additives are measured at various pressures and temperatures. Irganox 1010 is the most soluble and Irgafos 168 and Irganox 245 are least soluble in supercritical CO{dollar}\sb2{dollar}. The solubility was successfully correlated with CO{dollar}\sb2{dollar} density. Soxhlet extraction and conventional polymer dissolution procedures give similar results but require at least 24 hours in the case of the former and eight hours for the latter.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
