title: Dynamic rheological studies of poly(p-phenyleneterephthalamide) and carbon nanotube blends in sulfuric acid.
abstract: We have studied the dynamic scanning of liquid-crystalline (LC) poly(p-phenyleneterephthalamide) sulfuric acid (PPTA-H(2)SO(4)) solution, and its blend with single-walled carbon nanotubes (SWNTs), by using a flat plate rotational rheometer. The effects of weight concentration and molecular weight of PPTA, as well as operating temperature, on dynamic viscoelasticity of the PPTA-H(2)SO(4) LC solution system are discussed. The transition from a biphasic system to a single-phase LC occurs in the weight concentration range of SWNTs from 0.1% to 0.2%, in which complex viscosity reaches the maximum at 0.2 wt% and the minimum at 0.1 wt%, respectively, of SWNTs. With increasing SWNT weight concentration, the endothermic peak temperature increases from 73.6 to 79.9 degrees C. The PPTA/SWNT/H(2)SO(4) solution is in its plateau zone and storage modulus (G') is a dominant factor within the frequency (omega) range of 0.1-10 rad/s. As omega increases, the G' rises slightly, in direct proportion to the omega. The loss modulus (G'') does not rise as a function of omega when omega < 1 s(-1), then when omega > 1 s(-1) G'' increases faster than G', yet not in any proportion to the omega.
authors.affiliation: Donghua University, Shanghai, China. caoyt@hotmail.com <caoyt@hotmail.com>
authors.forename: Yutong
authors.initials: Y
authors.lastname: Cao
authors.forename: Zhaofeng
authors.initials: Z
authors.lastname: Liu
authors.forename: Xianghua
authors.initials: X
authors.lastname: Gao
authors.forename: Junrong
authors.initials: J
authors.lastname: Yu
authors.forename: Zuming
authors.initials: Z
authors.lastname: Hu
authors.forename: Ziqi
authors.initials: Z
authors.lastname: Liang
mesh_terms: D004548:Elasticity; D050866:Liquid Crystals / Q000737:chemistry; D008970:Molecular Weight; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010795:Phthalic Acids / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D012212:Rheology; D013464:Sulfuric Acids / Q000737:chemistry*; D013696:Temperature; D014783:Viscosity
chemical_list: D037742:Nanotubes, Carbon; D010795:Phthalic Acids; D011108:Polymers; D013464:Sulfuric Acids; C073843:poly(4-phenylene terephthalamide); C033158:sulfuric acid