혼합용매계에서 묽은 PET용액의 점도거동 : 2, 용매(1)-비용매(2)-고분자(3) 3성분계

박태경; 이장우

Polymer(Korea), Vol.15, No.4, 411-416, August, 1991

Viscosity Behavior of Dilute Solutions of PET in Mixed Solvents : 2. Solvent(1) - Nonsolvent(2) - Polymer(3) Ternary System

박태경, 이장우

초록

용매(1)-비용매(2)-고분자(3)의 3성분계를 대상으로 2종류의 혼합용매계에서의 점도거동에 관하여 조사하였다. 그리고 용매로서는 hexafluoroisopropanol(HFIP)과 trifluoroacetic acid(TFA)를, 그리고 비용매로서는 chloroform을 사용하였다. 혼합용매의 조성, 온도, 분자량 등에 따라 고유점도에 영향을 미치는 용해능의 변화에 관하여 살펴보았고. 혼합용매속에서 고분자의 점도 거동은 그 성분단 상호작용 파라미터(X_ij)에 의해 크게 영향을 받게 됨을 알 수 있었다. TFA-chloroform-PET 3성분계는 X₂₃-X₁₃ < X₁₂의 경우에 속하는 점도거동을 보였는데 특정조성에서 최대의 용해능을 나타내는 "cosolvency" 현상이 관측되었다. 그리고 이 계에서는 일반적으로 온도가 상승할수록 고유점도가 저하하였다. 반면 TFIP-chloroform-PET 3성분계는 X₂₃-X₁₃ > X₁₂의 경우에 속하는 점도거동을 보였는데 혼합용매의 조성변화에 따라 용해능은 단조변화하였다. 이 계에서는 HFIP-rich 영역에서는 온도의 상승에 따라 고유점도가 저하하는 경향을 보였으나, chloroform-rich영역에서는 정반대의 경향을 보였다.

The viscosity behavior of the PET polymer in mixed solvents has been investigated for two kinds of the solvent(1) -nonsolvent(2) -polymer(3) systems : hexafluoroisopropanol(HFIP) and trifluoroacetic acid (TFA) as solvents and chloroform as nonsolvent. Through the analysis of the effects of the composition of the mixed solvent, temperature (T), and molecular weight of PET on the solvent power affecting the intrinsic viscosity(Ⅳ), the viscosity behavior of polymer in mixed solvents has been found to largely depend on the binary interaction parameters(χ₂₃). The TFA/chloroform/PET ternary system exhibited the viscosity bahavior belonging to the case, χ₂₃-χ₁₃ < χ₁₂, and hence the "cosolvency" phenomenon, i.e. the occurrence of an optimum in the change of solvent power with composition of the mixed solvent. In addition, the IV generally decreased with the increasing T at a given composition of the mixed solvent. On the other hand the HFIP/chloroform/PET system showed the visicosity behavior of the case, χ₂₃-χ₁₃ > χ₁₂, i.e. a monotonic change of solvent power with the mixed solvent composition. As to the T dependence of Ⅳ for this system, the Ⅳ decreased with the increasing T at HFIP-rich regions, but the tendency was reversed at chloroform-rich regions.

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[14] Flory PJ, Fox TG, J. Polym. Sci., 5, 745 (1950)