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Showing 1 to 20 of 54 for “"Crystalline polymers."”.
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Fiber spinning and rheology of liquid-crystalline polymers
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1994.
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Multiscale Modeling of the Deformation of Semi-Crystalline Polymers
The mechanical and physical properties of polymers are determined primarily by the underlying nano-scale structures and characteristics such as entanglements, crystallites, and molecular orientation. These structures evolve in complex manners during the processing of polymers into useful articles. …
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A Least Squares Closure Approximation for Liquid Crystalline Polymers
… for the Doi-Hess kinetic theory of liquid crystalline polymers is provided. A new closure scheme is devised based on a least squares fit of a linear combination of the Doi, Tsuji-Rey, Hinch-Leal I, and Hinch-Leal II closure schemes. The orientation tensor and rate-of-strain tensor are fit …
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A model treating tensile deformation of semi-crystalline polymers
Semi-crystalline polymeric solids are usually in a state being built up of crystallites and an amorphous phase. A complex structure changing occurs in the polymer materials during the extension process. Uniaxial stretching of a semi-crystalline polymer sample causes the initial spherulitic …
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Thermoelectric and Charge Transport in Doped Semi-Crystalline Polymers
… and charge transport in highly conducting polymers. An unprecedented doping regime can be achieved via ion-exchange doping method, which is already approaching the metal-insulator (M-I) transition. The enhanced charge delocalization has been evidenced by the systematic spectroscopic as well …
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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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Studies on the rheology and morphology of thermotropic liquid crystalline polymers
… the physical properties of as-processed liquid crystalline polymers are highly dependent on the thermal and deformation histories of the materials experienced. The purpose of this study has been to examine the effect of thermal history on the rheology and morphological texture for several …
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The rheology and structure of thermotropic liquid crystalline polymers in extensional flow
… 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 isotropic systems of rodlike polymers. In order to accomplish this a rotary clamp extensional rheometer was …
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Process/Structure/Property Relationships of Semi-Crystalline Polymers in Material Extrusion Additive Manufacturing
… in most typical MEX processes, only amorphous polymers are being used as feedstock material owing to their smaller dimensional shrinkage during cooling and well-stablished process/structure/property (P/S/P) relationship. Semi-crystalline polymers, with their crystalline nature, possess unique …
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The synthesis, characterization and optical properties of novel diacetylene-containing aromatic liquid crystalline polymers
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1993.
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The Effects of Processing Conditions on Thermoplastic Prototypes Reinforced with Thermotropic Liquid Crystalline Polymers
… 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. Prototypes …
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A study of processing methods for producing biaxial orientation in thermotropic liquid crystalline polymers
Four methods of biaxial deformation were considered in an attempt to 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 …
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Processing and properties of composites based on high density polyethylene and thermotropic liquid crystalline polymers
… 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. Post-processing of the …
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Studies of blends containing liquid crystalline polymers with PET and related investigations of hydroquinone/biphenol polysulfone systems
… prepared from blends of thermotropic liquid crystalline copolyesters with polyethylene terephthalate (PET). Data were obtained which showed not only the temperature dependence of the moduli and stress-strain behavior but also the orientation effects that must be prevalent in order to explain …
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Multiscale simulation of viscoelastic flows : applications to kinetic theory models of polymer melts and liquid crystalline polymers
… flows of a modified Doi model for liquid crystalline polymer and a number of reptation models for polymer melts in different flow geometries.
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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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Determining the constants for an analyzing the predictive capabilities of a gas sorption model for semi-crystalline polymers
Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1992.
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The development of a dual extrusion blending process and composites based on thermotropic liquid crystalline polymers and polypropylene
… (DEP) which is used to blend thermotropic liquid crystalline polymers (TLCPs) with thermoplastics, determine the mechanism by which TLCP morphology is developed in the DEP and to determine the optimal properties possible in composite materials generated from the blends. The DEP consists of two …
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