Lyotropic Liquid Crystalline Behavior of Aromatic Polyamides(II) -Influence of Chain Rigidity on Rheological Properties-

방향족폴리아미드 용액의 액정특성(II) -고분자쇄의 경직성이 유성학적 특성에 미치는 영향-

Three kinds of polyamides with different chain rigidity, such as poly(4,4'-phenyleneterephthalamide) (PPD-T), poly(4,4'-terephthanilideadipamide) (PTAd) and poly(hexamethyleneadipamide) (PHAd), were prepared and dissolved in 100% sulfuric acid. The effect of chain rigidity on the liquid crystallinity was discussed in terms of rheological properties. In the vicinity of critical concentration loss tangent (tanδ) and ratio of dynamic visc osity to storage modulus (n'/G') gave a minimum value, but the ratio of storage modulus to twice loss modulus (G'/2G") and viscosity (n' and n*) showed a maximum value. Investigation of rheological properties reveals that the anisotropic solution system are similar to the suspension systems including deformable paritcles. The clear tendencies of yield behavior were observed for the lyotropic system of PPD-T in which no flexible units are incorporated in the main chain.