Browsing by Author "Young, Philip Ross"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Effluent analysis of model pyrrone compounds by gas chromatography
    Young, Philip Ross (Virginia Polytechnic Institute and State University, 1971)
    A gas chromatographic study was made to quantitatively analyze the effluents produced during the thermal cyclization of several polyimidazopyrrolone (pyrrone) model compounds. The study yielded information on analogous polymeric reactions. The model compounds were programed at 5° C/min from 25° to 400° C and volatile species were purged into a gas chromatograph at 25° intervals. An analysis of the effluents revealed that the cyclization reactions are concerted and generally occur below 250°C. The percent of conversion of the model compounds is readily determined by quantitating those reaction products amenable to gas chromatographic analysis. Only the amide-acid-amine and meta-benzimidazole-acid model compounds exhibited complete conversion to the pyrrone structure. Evidence that decarbo:xylation has occurred in the other compounds is presented.
  • Thumbnail Image
    The liquid chromatography of aromatic diamines: analytical and preparative
    Young, Philip Ross (Virginia Polytechnic Institute and State University, 1975)
    Liquid chromatographic methods were developed for determining the purity, reactivity, and preparative separation of aromatic diamine isomers used in the synthesis of aromatic polyimides. Approximately 50 diamine isomers were separated on various silica gels using chloroform and/or cyclohexane mobile phases. A linear relationship between pKb, and log of the capacity factor was discovered for four series of simple aromatic amines. This suggested that the relative basicities of more complex diamine isomers might be established from chromatographic retention data. A chromatographic basicity index for two series of isomers was then proposed and correlated with polymer viscosity measurements. Several parameters which can affect the efficiency of preparative separations of diamine monomers were also evaluated. These parameters included the effect of the column packing technique, flow rate, column diameter and length, adsorbent surface area and particle size, and column capacity. The results of this evaluation indicate that preparative liquid chromatography can be used to prepare highly purified milligram quantities of monomers for polymer synthesis.