The rheological characterization of the solutions of poly(2-cyano-p-phenylene terephthalamide) in N,N-dimethylacetamide/lithium chloride
Jung Dae Eon (1), Kim Chaejin (1), Jang Han Beol (1), Chung Dabin (1), Eom Youngho (1), Lee Eun Jeoung (1), Rho Kyeong-Hwan (2), Chae Dong Wook (3), Kim Byoung Chul (1)*
(1) Department of Organic and Nano Engineering, Hanyang University - Seoul - SouthKorea, (2) Heracron Institute, Kolon Central Research Park, Kolon Industries, Inc. - Gumi - SouthKorea, (3) Department of Textile Engineering, Kyungpook National University - Gyeongsangbuk-do - SouthKorea
The cyano-introduced p-aramid, poly(2-cyano-p-phenylene terephthalamide) (CY-PPTA), is dissolved in the mixture of N,N-dimethylacetamide with lithium chloride, whose solution can be used in the in-situ dry jet-wet spinning of the polymer. The rheological properties of CY-PPTA solution were investigated with respect to concentration and temperature. The solution exhibited a lyotropic liquid crystalline behavior but showed different temperature dependence compared with PPTA solution in fuming H2SO4. The critical concentration (C*) of CY-PPTA solution was decreased as temperature was increased. The optical observation of liquid crystalline texture further supported this. The viscosity curve following the Asada-Onogi model was more noticeable at lower concentration with increasing temperature. The concentration giving a maximum yield stress got closer to the C* at higher temperature. All these experimental results indicated that the CY-PPTA solution was an LCST system. On the whole, the yield stress gave a minimum at the B-point over the concentration range observed. In addition, the B-point of the solution shifted to higher concentration at higher temperature, whose reason is not clearly understood at this time.