Pal Application To the Study of Sorption Mechanism in Polymers - Capillary Effects

Y. Itoa, A. Shimadzub and K. Ikedab a Research Center for Nuclear Science and Technology, The University of Tokyo, Tokai, Ibaraki 319-11, Japan b Nitto Denko Corporation, 1-1-2, Shimohozumi, Ibaraki, Osaka 567-8680, Japan

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The positron annihilation lifetime technique can be applied to the study of the sorption mechanism in polymers in a quite unique way. In our previous experiments it had been shown that τ3 and I3 of polymers show a V-shaped dependence as a function of the contact with vapors. The decreasing part of the V-shaped dependence had been attributed to the Langmuir-type sorption, and the increasing part to delayed occurrence of the Henry-type sorption. But since there was some doubt that a capillary effect, i.e. the vapor to be sorbed is deposited in between the polymer membranes, might be involved in the increasing part, we performed a careful experiment to avoid the capillary effect. We have performed further experiments in a careful condition to avoid the capillary effect, and have observed the same V-shape as before. Thus our interpretation of the V-shaped dependence has been established. Furthermore, in another example it is shown a case where the capillary effect is observed. This latter case is an example how positron annihilation lifetime can distinguish the real sorption and false sorption (capillary effect).

DOI: 10.12693/APhysPolA.95.546 PACS numbers: 78.70.Bj