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Showing 1 to 20 of 59 for “"Thermotropic"”.
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Effects of solvents on thermotropic liquid crystalline copolyesters
Morphological studies were carried our on thermotropic liquid crystalline copolyesters based on poly(ethyleneterephthalate) (PET) and para hydroxybenzoate (PHB), where PHB content varied from 0 mole percent up to 80 mole percent. The technique of chemical etching coupled with SEM and WAXS was …
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Thermotropic and lyotropic mesophases formed by some lithium soaps.
… of each system was critically dependent upon the thermotropic polymorphism of the solvent-free soap itself. At high temperatures two distinct mesophases were formed in the LiPS-l-phenylheptane system; a solvent-swollen reversed hexagonal mesophase at low solvent concentrations and a novel reversed …
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Selection of Thermotropic Liquid Crystalline Polymers for Rotational Molding
Thermotropic liquid crystalline polymers (TLCPs) possess a number of physical and mechanical properties such as: excellent chemical resistance, low permeability, low coefficient of thermal expansion, high tensile strength and modulus, and good impact resistance, which make them desirable for use in …
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A Numerical Evaluation of Thermotropic Materials for Polymer Solar Thermal Collectors
A series of numerical studies of thermotropic materials are conducted to develop a theoretical basis for the selection and design of phase change thermotropic materials for polymer collectors. The optical requirements for a thermotropic material to provide overheat protection are identified. In the …
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Synthesis of a renewable sourced thermotropic polyester with 2,5-furandicarboxylic acid
… properties of a totally renewable sourced thermotropic polyester based on FDCA. Fructose was converted to 5-hydroxymethylfurfural, which was then used to synthesize the FDCA monomer. A polycondensation reaction involving 4-hydroxybenzoic acid, hydroquinone, and FDCA was subsequently carried …
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Studies on the rheology and morphology of thermotropic liquid crystalline polymers
… rheology and morphological texture for several thermotropic liquid crystalline polymers. These include two copolyesters of para-hydroxybenzoic acid and polyethylene terephthalate and a copolymer of para-hydroxy benzoic acid and 6-hydroxy-2-naphthoic acid. For all three systems, it was found that …
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The rheology and structure of thermotropic liquid crystalline polymers in extensional flow
The transient shear and elongational flow behavior of HPC EF, G, and HBA/HNA (Vectra A900) have been measured in order to determine the behavior of liquid crystalline polymer systems and to establish whether this behavior is different from that for isotropic flexible-chain polymer melts and …
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Morphology, Crystal Structure, Phase Transitions and Blend Compatibility of Thermotropic Liquid Crystal Terpolyesters
Compatibility of P7 and P7-X in binary blends with polyethylene (PE), polyethylene terephthalate (PET), and nylon 6 (Ny6), was examined to evaluate the effect of the aliphatic segment in promoting good adhesion at the interphase. Partial compatibility was observed for PE blends, while miscibility …
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Processing of composite fibers based on polypropylene and a thermotropic liquid crystalline polymer
… (PP) was reinforced with Vectra B950 (VB), a thermotropic liquid crystalline polymer (TLCP), in two novel fiber spinning processes. In one process, a single VB melt stream was surrounded by a sheath of PP in a manner comparable to a wire coating process just prior to melt spinning to generate …
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Structure and Dynamics of Thermotropic Liquid Crystalline and Solid Phases of Sodium Alkanoates (Nmr)
The neat (smectic A) phase of anhydrous sodium alkanoates is studied by means of NMR, polarization microscopy, and X-ray diffraction. The domain sizes, ('23)Na spin-lattice relaxation times T(,1), and the ('23)Na quadrupolar coupling constants (QCC) in neat phase sodium 3- and 4-methylpentanoates …
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Morphology and crystal structure of random, main chain, semi-flexible, thermotropic liquid crystal polymers
… structure and morphology of random, main chain, thermotropic liquid crystal polymers (LCP's) of equimolar amounts of the following structural units (with n equal to 4, 5, 6 and 7 in ""A"") have been examined by electron microscopy and diffraction:(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE …
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The Effects of Processing Conditions on Thermoplastic Prototypes Reinforced with Thermotropic Liquid Crystalline Polymers
… (PP) strands reinforced with continuous thermotropic liquid crystalline polymer (TLCP) fibrils were generated in a novel dual extruder process. Strands were then re-extruded to form short fiber composite monofilaments that were used as feed stock in the FDM 1600 rapid prototyping system. …
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A study of processing methods for producing biaxial orientation in thermotropic liquid crystalline polymers
… obtain biaxial orientation and properties in two thermotropic copolyesters: hydroxybenzoic acid-co-polyethylene terephthalate (HBA/PET) and hydroxybenzoic acid/2, 6 hydroxynaphthoic acid (HBA/HNA). They consisted of solid phase forming, extrusion blow molding, biaxial stretching, and film blowing. …
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Phase Transitions and the Effect of External Fields in Thermotropic Main Chain Liquid Crystal Systems
… was to investigate the unique behavior of thermotropic main chain liquid crystal polymers with regard to phase transitions and their response to surfaces and external fields. Three different aromatic polymers were utilized in this study, including two constitutional isomers with periodic …
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Processing and properties of composites based on high density polyethylene and thermotropic liquid crystalline polymers
… of high density polyethylene (HDPE) and thermotropic liquid crystalline polymers (TLCPs). Strands of HDPE reinforced with TLCPs were generated using a novel dual extruder mixing technique. It was shown that the strength and modulus of the strands improved with increased strand drawing. …
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FABRICATION OF FUNCTIONAL NANOSTRUCTURED POLYMERS BASED ON THERMOTROPIC AND LYOTROPIC LIQUID CRYSTALS DERIVED FROM SUSTAINABLE RESOURCES
… functional materials can be realized from thermotropic and lyotropic liquid crystals derived from unsaturated fatty acids, and on the properties of the materials thus produced. While prior use of the so-called “molecular templating” approach has produced well-defined nanostructured …
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A biaxial nematic phase in a thermotropic liquid crystalline side-chain polymer : a deuterium NMR study
The goal of this thesis was the investigation of the phase symmetry of liquid crystalline side-chain polymers by means of deuterium NMR spectrodcopy. The lateral attachment of a book-shaped mesogen should - in the case of the system investigated in the beginning - prevent the rotation about the …
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Linking the Rheological Behavior to the Processing of Thermotropic Liquid Crystalline Polymers in the Super-cooled State
Thermotropic liquid crystalline polymers (TLCPs) have attracted great interest because of the combination of their promising properties, which includes high stiffness and strength, excellent processability, and outstanding chemical resistance. TLCPs exhibit inherently low viscosity relative to many …
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Reclamation and Reprocessing of Thermotropic Liquid Crystalline Polymer from Composites of Polypropylene Reinforced with Liquid Crystalline Polymer
… has been considerable interest in the use of thermotropic liquid crystalline polymers (TLCPs) to reinforce thermoplastic materials. In a novel process developed by Baird and coworkers, wholly thermoplastic composites are produced via a patented, dual extrusion process. This unique process …
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