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Full-Text Articles in Physical Sciences and Mathematics
Gas Permeation Measurements On Small Polymer Specimens, Karen S. Burns
Gas Permeation Measurements On Small Polymer Specimens, Karen S. Burns
Chemistry & Biochemistry Theses & Dissertations
Mass spectrometry was used to measure oxygen and nitrogen permeabilities while polarography was used to measure oxygen permeabilities for several contact lens materials. Applicable sample holders were designed and fabricated to accommodate curved and flat specimens with surface areas of 0.5 cm2 and 1.0 cm2 and thicknesses between 0.025 mm and 0.500 mm. A prepared standard was used to calibrate the mass spectrometric analyses.
The oxygen permeability values determined by mass spectrometry were significantly greater than those determined by polarography. This was attributed to the phase boundary phenomena and the limiting oxygen permeance of water inherent in the …
The Synthesis Of New Maleimide Addition Polymer Precursors, Richard B. Brown
The Synthesis Of New Maleimide Addition Polymer Precursors, Richard B. Brown
Chemistry & Biochemistry Theses & Dissertations
1H-2,3-dimethylpyrrolo(1,2-a) benzimidazol-l-one (27) and 1H,9H- 2,3,7,8-tetramethyl-bispyrrolo(1,2-a:6,7-a')benzodiimidazo1-1,9-dione (32) have been synthesized from dimethylmaleic anhydride and o-phenylenediamine and 1,2,4,5-tetraaminobenzene, respectively. The presence of reactive olefinic double bonds in the synthesized compounds was of interest as a site for possible addition polymerization.
The synthetic route involved, in both cases, a simple nucleophilic substitution reaction between the diamine(or tetraamine) and the anhydride to form an intermediate amide-acid-amine which rapidly cyclized to the imide amine. The final ring closure required more rigorous conditions and occurred at melt reaction temperatures.