Eom, Youngho Jung, Dae Eon Hwang, Seung Sang Kim, Byoung Chul 2024-01-20T03:34:06Z 2024-01-20T03:34:06Z 2021-09-05 2016-08 0032-3896 https://pubs.kist.re.kr/handle/201004/123820 The liquid crystalline (LC) behavior of two lyotropic systems, poly(p-phenylene terephthalamide) (PPTA) solutions in sulfuric acid and hydroxypropyl cellulose (HPC) solutions in water, was compared on a dynamic rheological basis. The critical concentration (C*) curves showed much sharper transitions in PPTA solutions than in HPC solutions. The C* and saturation point (B-point) were observed at 7 and 10.5 wt% for nematic PPTA solutions and at 40 and 53 wt% for cholesteric HPC solutions. Both lyotropic systems gave low yield stress (tau(y)) below 1 Pa at the B-point. With further increases in concentration, the ty values of nematic PPTA and cholesteric HPC solutions were 461.48 and 6.03, respectively. In the loss tangent (tan delta) curves versus frequency, the tand of PPTA was monotonically decreased, but that of HPC was increased in the early stage of frequency, and this trend was more noticeable at higher concentrations. Two systems showed similar behaviors in molecular stress relaxation but different orientation relaxation time behaviors. With increased strain, the orientation relaxation time (lambda(e)) of the PPTA solutions was slightly increased, but that of the HPC solutions was decreased, and their lambda(e) values converged at 100% strain. English NATURE PUBLISHING GROUP SULFURIC-ACID MOLECULAR-ORIENTATION PHYSICAL-PROPERTIES POLY(1,4-PHENYLENE TEREPHTHALAMIDE) NANOCOMPOSITES BEHAVIOR FIBERS WATER NANOPARTICLES COPOLYAMIDES Characteristic dynamic rheological responses of nematic poly(p-phenylene terephthalamide) and cholesteric hydroxypropyl cellulose phases Article 10.1038/pj.2016.46 1 POLYMER JOURNAL, v.48, no.8, pp.869 - 874 POLYMER JOURNAL 48 8 869 874 scie scopus 000382031000005 2-s2.0-84982958152 Polymer Science Polymer Science Article SULFURIC-ACID MOLECULAR-ORIENTATION PHYSICAL-PROPERTIES POLY(1,4-PHENYLENE TEREPHTHALAMIDE) NANOCOMPOSITES BEHAVIOR FIBERS WATER NANOPARTICLES COPOLYAMIDES dynamic rheological responses liquid crystalline polymer poly(p-phenylene terephthalamide) hydroxypropyl cellulose