Three segmented mainchain thermotropic liquid crystalline polymers tlcps functionalized with nitrogencontaining heterocyclic groups were synthesized. The subject of liquid crystalline polymers lcps transcends classical polymer chemistry and physics, and it extends tile conventional boundaries of theology and processing. Schematic drawing of the conformations of liquid crystalline polymers in nematic solvents. Optical microscopy, xray scattering, and differential scanning calorimetry are employed for the structure investigation and rheology for the dynamics. Modeling directionality of liquid crystalline polymers on. The threeregion logarithmic viscosity curve of thermotropic liquid crystalline polymers scheme based on the by onogi and asada theory. Processing rheology of liquid crystalline polymers. In turn, to form a dilute polymer network it is necessary to use very long polymers that are soluble in the small molecule lc.
These two parts of the simulation are performed independently. We report on the structure and the viscoelastic properties of two sidechain liquid crystalline polymers with different spacer length in the melt and fiber states and of their copolymers with a semicrystalline block. Chapters 5 and 6 summarize the properties and applications of liquid crystalline polymers. Wormlike micelles and lamellar liquid crystalline phase o.
The effect of flexible spacer length on the rheology of sidechain liquid crystalline polymers sclcps was investigated. Liquid crystalline mainchain polymers with a polypphenylene terephthalate backbone. Rheological properties of some thermotropic liquid. Rheology and processing of liquid crystal polymers domenico. Puig encyclopedia of life support systems eolss amended the energy expression to consider cylinders. Liquid crystal polymers lcps have many strange properties that may be utilized to advantage in the processing of products made from them and their blends with isotropic polymers.
Liquid crystalline polymer an overview sciencedirect. This classification is based on the place in the polymer where the mesogen is inserted, i. Rheology and rheooptics of polymer liquid crystals. To form a liquid crystalline lc gel that retains the ability to respond rapidly to applied fields, it is necessary to work with low polymer concentrations. Rheology of a liquid crystalline polymer dispersed in a flexible polymer. This article summarizes recent experiments relating measurements of molecular orientation to bulk rheological behavior in liquid crystalline polymers lcps under shear. The simulations present a first attempt to describe the rheological properties of thermotropic liquid crystalline polymers lcps, using recently developed thermodynamic theory of weakly. The total polymer concentration in the solvent is held constant 40% as the ratio of the two polymers. If you have a user account, you will need to reset your password the next time you login.
Walters, department of mathematics, university college of wales, aberystwyth, u. Liquid crystal polymer an overview sciencedirect topics. The rheological and optical properties are most important properties to characterize the liquid crystalline state, and therefore studies on the viscosity have been performed before 1900. Synthesis, characterization, and rheology of functional.
Quantitative measurements of molecular orientation and rheology are reported for various transient shear flows of a nematic semiflexible copolyether. Conclusion glossary bibliography biographical sketches summary liquid polymeric systems have a characteristic rheological. Rheology of polypropyleneliquid crystalline polymer. At the present stage little is known about the second normal stress difference of tlcps and we found it. Optical rheology of new liquid crystalline thermosets. At solution concentrations just beyond that of the isotropic. A liquid crystal polymer has a particular kind of structural orientation at one or two dimensional level. Rheology of liquid crystalline polymers sciencedirect. Effect of shear rate on the orientation and relaxation of a. Rheology of liquid crystalline polymers semantic scholar. The tgb a is a liquid crystalline analog of the abrikosov phase exhibited by typeii superconductors 5. Rheology and dynamics of solutions of side group liquid.
Molecular composites from liquid crystalline polymers and liquid crystalline thermosets b. Rheology of heavy crude oil and asphaltene polymer composite blends 10. Optical rheology of new liquid crystalline thermosets lcts. Liquidcrystalline polymers gas permeability of liquidcrystalline polymers is derived from low oxygen diffusivity and low oxygen solubility. Rheological properties of polymeric liquid crystals. Kl tse, ad shinetwodimensional modeling of the electrorheological behavior of liquid crystalline polymer solutions. This structural orientation makes the rheological properties of liquid crystal polymers. Studies on the transient shear flow behavior of liquid. Although there has been progress on the theory of diffusion and rheology of rigidrod polymers in dilute and semidilute solutions, very little is known about these properties in liquid crystalline solutions and bulk polymers. Rheological properties of some thermotropic liquid crystalline polymers koreaaustralia rheology journal september 2003 vol.
The rheological behavior of a mixture of two liquid. Connecting the rheological behavior to the processing of. Rheology of liquid crystalline polymers springerlink. Rheology and dynamics of sidegroup liquid crystalline. Influence of shear on disclination texture haihu qin and patrick t. This volume volume 2 in the series polymer liquid crystals deals with their strange flow behaviour and the models put forward to explain the phenomena that. Sidechain liquidcrystalline homopolymers and copolymers. Liquid crystalline polymers can be classified into main chain, side chain and combined figure 3. Thermotropic liquid crystal polymers tlcps, which contain a special monomer chemical structure, are already widely used as highperformance commercial engineering polymers owing to their good thermal properties, high strength, high modulus, low viscosity, and other excellent mechanical properties 1,2. Connecting the rheological behavior to the processing of thermotropic liquid crystalline polymers in the supercooled state chen qian.
Electric field effect on the rheology of mwcnt dispersions. Rheology of thermotropic liquid crystal polymers for injection moulding a thesis submitted in fulfilment of the requirements for the degree of doctor of philosophy. Abstract the flow of the nematic phase of liquid crystalline polymers exhibits a much more complex phenomenology than that shown by either an ordinary polymer or a low molecular weight nematic. Optical microscopy, xray scattering, and differential scanning calorimetry are employed for the structure investigation and rheology. Typical conventional thermoplastic polymers, such as polypropylene and polystyrene, are based on long, linear chain, molecules. Effect of flexible spacer length on the rheology of side. Transient molecular orientation and rheology in flow.
Mathera,b polymer graduate programa and chemical engineering departmentb university of connecticut, storrs, ct 06269 abstract liquid crystalline. Rheology, phase equilibria and processing of lyotropic. Chapter 5 deals mainly with mechanical performance in fiber and composites. Liquid crystalline phases solid particles acid can also be applied as emulsi. Rheology of polymer blends and nanocomposites 1st edition. For example, the normal stress effect in a shear flow, which in ordinary polymers. Molecular crystals and liquid crystals incorporating nonlinear optics. Properties of these new materials are, on the one hand, reminiscent of amorphous metals, while simultaneously exhibiting attributes of organic single crystals. Crystalline polymeric systems article pdf available in journal of engineering physics and thermophysics 761. Rheology of polymeric liquid crystals sciencedirect. Many studies have correlated the structures of tlcps with their characteristics 3,4,5. More complex polymer architectures are also possible.
Studies on the transient shear flow behavior ofliquid crystalline polymers g. As a result, four different cal culations need to be done for the flow to be fully simu lated. Rheology and processing of liquid crystal polymer melts springerlink. The transient extensional viscosity of the nematic melt of thermotropic liquid crystalline lcp copolyester vectra a950 was measured in uniaxial extensional flow in a commercial constant. This research focuses on the synthesis of ultralong sidegroup liquid crystalline polymers. Rheology, phase equilibria and processing of lyotropic liquid crystalline polymers. Mixtures of polymers and surfactants are ideal in achieving ease of emulsi. Pdf simulations of shearing rheology of thermotropic. Pdf rheometry testing and the dsc measurement of five thermotropic liquid crystalline polymers tlcp have been carried out.
Rheology of thermotropic liquid crystalline polymers tlcps are a class of highperformance engineering thermoplastic polymers with lmw. And then rheooptical properties of these liquid crystalline polymers. Electric field effect on the rheology of mwcnt dispersions in liquid crystalline polymers ana r. Molecular orientation and rheology in sheared lyotropic. Vapor liquid equilibrium data of the liquid crystalline system with co 2 was recorded up to a co 2 partial pressure of 6 bar, where a loading of 38. Rheology of liquid crystalline polymers iopscience. After a brief introduction to liquid crystals in general and their rheological properties, the rheology of liquid crystalline polymers is summarized by the threeregion flow curve. This volume volume 2 in the series polymer liquid crystals deals with their strange flow behaviour and the models put forward to explain the phenomena that occur in such polymers. Chapter 6 presents the elasticity, viscosity and rheology of liquid crystalline polymers. Baird polymer materials and interfaces laboratory anddepartment ofchemical engineering, virginia polytechnic institute and state university, blacksburg, va 240616496 synopsis an understanding of the flow behavior of liquid crystalline polymers. Rheology and processing of liquid crystal polymers. The d isti nctiv e fe atu r es of th e media in question in the case of shear flow have been described using this theory.839 881 1414 122 1271 1013 920 398 1080 619 21 1188 481 631 1360 414 452 369 1218 714 1592 1478 565 1000 261 862 1303 1467 372 505 1264 167 17 971 1322 912 637 832 1310 553 946 590