Effect of Degree of Polymerization and of Temperatute on the Reactivity of Poly (Vinyl Alcohol) by Applying T-for-H Exchange Reaction

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  • IMAIZUMI Hiroshi
    Department of Chemistry and Chemical Engineering, Faculty of Engineering, Niigata University
  • IMAI Kazunari
    Graduate School of Science and Technology, Niigata University

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Other Title
  • ポリ (ビニルアルコール) の反応性に及ぼす重合度および温度の影響 (T-for-H交換反応の利用)
  • ポリ ビニルアルコール ノ ハンノウセイ ニ オヨボス ジュウゴウド オヨビ オンド ノ エイキョウ T-for-H コウカン ハンノウ ノ リヨウ

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Abstract

In order to reveal the effect of the degree of polymerization and of temperature on the reactivity of functional polymers, the hydrogen-isotope exchange reaction between poly (vinyl alcohol) (PVA) having each degree of polymerization and tritiated water vapor (HTOvapor) was dynamically observed at 35-80°C in a gas-solid system. The reason of the observation at 35°C is to clarify the possibility of theT-for-H exchange reaction at a temperature near the environment. The degree of polymerization of PVA used in this work was 500, 1000, 2000, 2800, or 3500. Applying the A″-McKay plot method to the data obtained in each observation, the rate constant (k) for each PVA in the reaction was calculated. Moreover, the Arrhenius plot for each PVA was made by using the k values. Comparing the k values and the results obtained previously, the following six matters have been clarified. (1) In the temperature range of 35-80°C, the T-for-Hexchange reaction betweenHTOvapor and each PVA occurred, and in this case, the atoms participating in the reaction are theHatoms in theOHgroups in PVA andTatoms inHTOvapor. (2) The reactivity of each PVA increases with rising temperature, and decreases with increasing the degree of polymerization. (3) The rate of the decreasing of k with increasing the degree of polymerization changes at near the degree of polymerization of 1000, and the rate is fairly large under the degree of 1000. (4) Under the degree of polymerization of 1000, the reactivity of PVA is more affected by the effect of the degree of polymerization than by the effect of temperature, and the reactivity is large when the degree of polymerization is small. (5) Over the degree of polymerization of 1000, the reactivity of PVA is affected by both the degree of polymerization and temperature, and the reactivity is large when temperature is high. (6) For theT-for-Hexchange reaction in a gas-solid system, the reaction form is unchanged in the range of 35-80°C, and the reactivity at 35°C cannot be neglected.

Journal

  • RADIOISOTOPES

    RADIOISOTOPES 48 (12), 713-719, 1999

    Japan Radioisotope Association

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