CORRELATION BETWEEN POSITRON-ANNIHILATION AND SORPTION OF CO2 IN GLASSY-POLYMERS

The lifetime and the intensity of ortho-positronium (o-Ps), tau3 and I3 respectively, were measured for polyimides and non-imide polymers in glassy state. Average size of free space holes probed by o-Ps, v(h,Ps) is calculated from tau3 using an empirical equation. Correlations between sorption of CO2 and the positron annihilation (PA) properties are discussed. The Langmuir capacity constant C(H)' of the dual-mode sorption model is well correlated with v(h.ps), suggesting that the larger v(h,Ps), reflects the higher volume fraction of holes large enough to be available for the Langmuir type sorption. The Henry's law solubility constant k(D) is also correlated with v(h,Ps), indicating that the polymers packed less-efficiently tend to have larger k(D). As a result, there is a tendency that solubility coefficient of CO2 at 10 atm, S(CO2), increases with v(h,Ps). The C(H)', k(D), and S(CO2), are also correlated with v(h,Ps)I3 for only the polyimides, and the correlations are a little worse than those with v(h,Ps).