Determination of Molecular Weight and Its Distribution of Phenolic Resins by Gel Permeation Chromatography

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Other Title
  • ゲルパーミエーションクロマトグラフィーによるフェノール樹脂の分子量および分子量分布測定法

Description

A few factors which affect the accuracy of the determination of molecular weight and its distribution of phenolic resins were discussed. For the purpose of improving the accuracy, a new calculation method for molecular weight is proposed. The method can be applied to discontinuous GPC curves of phenolic resins, epoxy resins and other thermosetting uncured oligomers. The net peak area which corresponded to the dimer fraction was obtained by integrating the peak area from the middle point between the monomer peake and the dimer peak to the middle point between the dimer peak and the trimer peak. Similarly, the net peak areas of a trimer, a tetramer, a pentamer and so forth can be obtained in the same way as above.<BR>The other successive calculation procedures for molecular weight determination were the same as taken for GPC curves of such polymer as polyethylene. Pore sizes of polystyrene gels were 5000-45000A, 700-2000A, 350-700A and 50-80A. Tetrahydrofuran was used as carrier solvent at room temperature. The flow rate was 1 ml/min.<BR>Mw was found more available than Mn as the cure index of phenolic resins because of its high sensitivity to high molecular weight fractions. The range of polydispersity (Mw/Mn) of phenolic, p-terbutylphenolic and p-phenylphenolic novolac resins was between 1-2, and Mw/Mn of fractions by the solvent fractionation method was between 1.12 and 1.36 to 1.44 of the original resin.<BR>Furthermore, it was found that a small amount of molecular weight fraction above 5000 exists in uncured phenolic novolac and resole resins.

Journal

  • NIPPON KAGAKU KAISHI

    NIPPON KAGAKU KAISHI 1972 (4), 800-806, 1972-04-10

    The Chemical Society of Japan

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