自由体積概念に基づく高分子混合系物性の記述

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In a system of polymer blends, which is composed of n kinds of component polymers, free volume fraction of i component (f_i) is assumed to be by Eq. (1). f_i=f_<i,0>+Σ^^n__<j=1> a_i^j V_j+Σ^^n__<j=1> Σ^^n__<k=1> b_i^<jk> V_j V_k+…… (1) where suffixes i,j and k mean components i,j and k respectively, and the suffix 0 means the value before blend. V is a volume fraction of component and a_i^j is a coefficient, which becomes zero when i equals j and b_i^<jk> a coefficient which become zero when i equals j or when i equals k. The relationships between the glass transition temperature T_g and the composition for various types of polymer blend were derived from Eq. (1) for the two component system. The relationships for perfectly miscible system, random copolymer system and microheterogeneous system are expressed as follows; T_g=(V_1 Δα_<1,0> T_<g1,0>+V_2Δα_<2,0> T_<g2,0>)/Δα+V_1V_2(B+CV_1)/Δα } Δα=V_1Δα_<1,0>+V_2Δα_<2,0>-V_1V_2(B'+C'V_1) (2) where Δα is the expansion coefficient of free volume fraction and B, C, B' and C' are constants including α_i^j and b_i^<jk> of Eq. (1). The values of a_i^j for various kinds of polymer blend were obtained from T_g values observed as a function of composition and the physical meanings of a_i^j were discussed. Assuming that the blend system is composed of many cells with different value of free volume, we newly defined a distribution function of free volume fraction F(f), to explain the behavior of actual polymer blend. The function F(f) could be obtained from the specific volume-temperature curve. By using it, we could express the mixing state of polymer blends and explain their viscoelastic behavior near glass transition temperature. These results can be applied to the various types of copolymers.
社団法人日本材料学会の論文
1968-04-15

自由体積概念に基づく高分子混合系物性の記述

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