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정대언,엄영호,윤후영,이재영,김병철 한국고분자학회 2016 Macromolecular Research Vol.24 No.2
The lyotropic liquid crystalline behavior of poly(2-cyano-p-phenylene terephthalamide) (CY-PPTA) solution in the mixture of N-methyl-2-pyrrolidone and calcium chloride was investigated in terms of concentration and temperature. The intrinsic viscosity was decreased with increasing temperature, indicating the contraction of CY-PPTA chain at higher temperature. In dynamic viscosity measurement, the critical concentration (C*) where phase transition to the liquid crystalline phase takes place was decreased with increasing temperature. Above the C*, the dynamic viscosity was decreased and Bingham behavior got more noticeable with increasing concentration due to the development of the liquid crystalline structures. However, Bingham behavior was more notable at higher temperature at a given concentration. The viscosity curves showed the three distinct flow regions suggested by Asada and Onogi and negative first normal stress difference was observed in the range of intermediate shear rates.