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Showing 1 to 20 of 35 for “"Intrinsic Viscosity"”.
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Characterization of industrial flocculants through intrinsic viscosity measurements
… flocculants was investigated by determining intrinsic viscosities on dilute flocculant solutions. The Fedors equation was found to be most suitable for all flocculants for determining the intrinsic viscosity. The results indicated that the flocculants are fully extended in distilled water at …
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Role of surface chemistry in sub-Einstein rheology of nano-composites
Sub-Einstein and negative intrinsic viscosities resulting from the addition of nano-fillers to polymer melts approximately 2-10 nm diameter have been reported. Here we explore the intrinsic viscosity of polyhedral oligomeric silisequioxane (POSS) particles of approximately 1.6-2.5 nm diameters as a …
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Structural Study of Natural and Synthetic Polymers
… as suggested from the increase of the intrinsic viscosity; the change of intrinsic viscosity was not sufficient to indicate coil-like conformation.
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Correlation of the distribution curve with the dispersion curve of cellulose nitrate
… curves. A relationship of the log frequency to intrinsic viscosity has been derived and appears to be acceptable with ±10% of the values obtained from fractional precipitation. Thus the distribution curve of cellulose nitrate may be determined from the dielectric dispersion curve.
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Thermodynamic and kinetic studies of purple membrane from halobacterium halobium
… photolysis to measure the effects of solvent viscosity on the kinetics of the purple membrane photocycle, and we analyzed the data in terms of a modified Kramers' theory. In the second experiment, we determined the purple membrane's apparent density, thermal expansivity, isothermal and …
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Study of the rheological properties of nomex fibrids
… contain (spherical) fumed silica particulates as viscosity enhancers. A similar viscosity enhancement can be achieved by using aramid fibrids. Aramid fibrids are believed to form microstructures in suspensions because of the "space-filling" nature of their shapes and thus provide a convenient …
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Synthesis and characterization of poly (butyl vinyl ether) homopolymers and copolymers utilizing the aluminum hydrogen sulfate catalyst system
… permeation chromatography characterization and intrinsic viscosity data of poly(butyl vinyl ether), and poly{butyl vinyl ether-2-chloroethyl vinyl ether) homopolymers and copolymers indicate fairly narrow polydispersities, and very high molecular weights. A study of this copolymerization by lH …
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Synthesis and characterization of poly-(p-phenylene pyromellitamic acid)
… is a poor solvent for the polymer. The intrinsic viscosity - weight average molecular weight relationship was found to be [η] = 25.22 x 10⁻⁴ M̄<sub>w</sub>⁰.⁵⁶³ The poly(p-phenylene pyromellitamic acid)s were also characterized by ultraviolet, visible, near infrared, and infrared …
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The thermal degradation of polystyrene.
… the assumptions of the theory used to relate intrinsic viscosity to degree of degradation are shown to be essentially correct. Finally some suggestions are made for further work.
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Characterization of Fluoropolymer Powders Made By Supercritical Assisted Mixing With Crystalline Additives
… additives were extracted from the powders and intrinsic viscosity measurements were done on the remnant fluoropolymer. Viscosity studies showed that the virgin and post-ball milled fluoropolymers had similar intrinsic viscosities, hence similar molecular weights within experimental error …
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Synthesis of novel heterocyclic polymers via the chemistry of Reissert compounds
… that had the highest molecular weights and intrinsic viscosities. A novel N-heterocyclic difluorodiketone was prepared in four steps using the enamine reaction of Minter and Re52 and Reissert compound chemistry. The diketone was polymerized via standard techniques 72 to afford several novel …
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Synthesis, characterization and application of polyacrylamide grafted bioflocculants (TMT-1-g-PAM 2 and TST-1-g-PAM 3)
… 2 and TST-1-g-PAM 3) were then characterized by intrinsic viscosity, elemental analysis, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometry (XRD) and thermogravimetric analysis (TGA). Furthermore, these optimum grades’ biosafety (on human …
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Dilute solution studies of molecular weight distributions of nitrocellulose, modified lignins and PMMA graft polymers
… permeation chromatography with a differential viscosity detector (GPC/DV) was employed to study the dilute solution properties of various polymers, specifically their absolute molecular weight distributions and hydrodynamic behavior. The study was divided into three parts. The first part …
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Study of the miscibility, morphology, crystallization, and melting behavior of blends of poly(3-hydroxybutyrate) and poly(vinylidene fluoride)
… been affected by either blending procedure, but intrinsic viscosity studies indicate a dramatic decrease in PHB's viscosity average molecular weight after melt blending and a smaller decrease after solution blending. FT-IR studies were conducted to determine if PHB did crystallize in the same …
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Solution History Effects and Crystal Phase Transformation in Polybutene-1 and Domain Morphology in Polyurethanes
… crystal form. Measurements of the solution's intrinsic viscosity show that the hydrodynamic volume of a PB-1 molecule in solution varies considerably with the solution's thermal history, lending support to the idea of retention of helices in solution. The tetragonal (--->) twinned hexagonal …
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Solution properties and molecular size of polyhydroxybutyrate from recombinant Escherichia coli
… produced pure PHB showing greatly different intrinsic viscosities in chloroform. Strain pAeT41 produced PHB molecules nearly an order of magnitude larger in intrinsic viscosity than those produced by strain pSP2. This led to the hypothesis that high synthase concentration led to the …
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Molecular necklaces: polyester rotaxanes
… including NMR, UV, VPO, GPC, DSC, TGA, and intrinsic viscosity measurements. Significant amounts, up to 51 mass %, of the macrocyclic components were incorporated. Because of incorporation of flexible and polar macrocycles, polyrotaxanes display special behavior in solution and in the solid …
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Grewia polysaccharide gum as a pharmaceutical excipient
… ability of the material to increase solution viscosity has generated a lot of interest and is the catalysing momentum for this research. Such materials have been used as stabilizers or suspending agents in cosmetics, foods and liquid medications, and as mucoadhesives and controlled release …
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Polysiloxane-polyarylester block copolymers: synthesis and characterization
… and block copolymers were successfully prepared. Intrinsic viscosity measurements, size exclusion chromatography, and the fact that tough transparent films could be solution cast and compression molded indicated that relatively high molecular weight materials were prepared. Due to the high degree …
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Kinetic and mechanistic investigations of polyimide formation and characterization of their blends with polybenzimidazoles
… were observed via combination of NMR and intrinsic viscosity measurements. However, complete "recombination" of the degraded polymer chains and their further cycloimidization could be achieved under proper imidization conditions. Potential side reactions involving intermolecular imide …
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