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  • 1
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 1759-1765 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Fluorescence spectroscopy has been employed to monitor the mixing of polymer melts with filler material. The polymer melts were low molecular weight polybutadiene and PBAN, a terpolymer consisting of 85% butadiene, 11% acrylonitrile, 4% acrylic acid, and the filler material was aluminum oxide. To carry out the fluorescence observations, a dopant chromophore was mixed into the polymer melt at very low concentrations, 10-4 to 10-6 molar or 11 to 0.11 ppm by weight. The mixing experiments were carried out using a small laboratory mixer which had glass walls for viewing the fluorescence spectra from the dopant chromophore. Fluctuations in fluorescence intensity were observed to decrease as a function of mixing time indicating that the spatial distribution of the fluorescent chromophores was becoming more uniform. Concerning the mixing of polymer melt and filler, we hypothesize that uniform mixing of ingredients is achieved when fluorescence intensity as a function of time is constant. In order to obtain quantitative support for this hypothesis, we used a fluorescence microscope to measure fluorescence intensity and optical transmittance from microscopic regions of well-mixed and poorly mixed specimens.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 505-508 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 24 (1978), S. 204-212 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An analysis is presented for the flow separation process in hydrodynamic chromatography along with comparisons to experimental data. The flow separation model is based on calculations for the convected Brownian motion of colloidal particles in a capillary tube in the presence of a force field. The results indicate the role of the relevant experimental parameters in the separation process.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 671-679 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An optical sensor, consisting of optical fibers to transmit light to and from the mold cavity, was constructed for the purpose of measuring the onset of polymer solidification during injection molding. The sensor was used to detect characteristic fluorescence radiation from a dye which had been doped into the resin at very low concentration. By measuring changes in fluorescence intensity it was possible to detect whether the state of the resin was liquid or solid. We observed that, as the resin cooled in the mold, the onset of solidification was indicated by highly characteristic and distinct changes in the fluorescence intensity/time profile. Application of the method involved the use of a calibration relationship between the fluorescence intensity and temperature of the doped polymer in order to determine the distict features which characterize the onset of solidification. Injection molding of a glass forming polymer (polystyrene) and a crystallizable polymer (polyethylene) was monitored by this technique.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 573-581 
    ISSN: 0887-6266
    Keywords: polyether polyol ; polyurethane foam ; block-segmented copolymers ; microphase separation ; optical microscopy ; transmission electron microscopy ; small-angle X-ray scattering ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of flexible polyurethane slabstock foam samples were prepared with varying water content and studied using transmission electron microscopy (TEM), video-enhanced optical microscopy (VEM), and small-angle X-ray scattering (SAXS). A new TEM sample preparation technique was developed in which the foam is impregnated with water, frozen, and microtomed, and the polyether soft segment is selectively degraded in the electron beam. Structures of two size scales were detected. A texture with grains (“urea aggregates”) 50-200 nm in size was imaged using both VEM and low-magnification TEM for foams with formulations containing more than 2 pphp water. For the first time, images of urea hard segment microdomains in polyurethane foam (approximately 5 nm in size) were obtained using high-magnification TEM. A microdomain spacing of approximately 6-8 nm was estimated from the SAXS scattering profiles. Glycerol was added to one of the formulations in order to modify the urea microphase separation and to give insight into morphology development in molded polyurethane foam systems. No structure was observed in low-magnification TEM images of the glycerol-modified foam, although smaller structures (hard segments) were detected at high magnification and by SAXS. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 573-581, 1998
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 2629-2643 
    ISSN: 0887-6266
    Keywords: microphase-separated diblock copolymer ; conformational asymmetry ; epsilon parameter ; TEM ; SAXS ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The equilibrium morphological behavior of a series of conformationally asymmetric linear diblock copolymers is characterized via small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The linear diblock molecules of polyisoprene and poly(t-butylmethacrylate) (PtBMA) are prepared anionically over a range of PtBMA volume fractions 0.17 to 0.85. Solution light-scattering experiments are performed on PtBMA homopolymer at theta conditions, and the results were compared with PI data in the literature in order to characterize the degree of conformational asymmetry between the respective blocks. This conformational asymmetry is quantified by an ε of 0.75. The experimental results are compared with morphological behavior calculated utilizing self-consistent mean field theory for a diblock system with ε = 0.75. At middle to high PtBMA volume fractions, φPtBMA 〉 0.30, the experimental morphological behavior agrees well with the calculated behavior; the microphase boundaries are slightly shifted to higher volume fractions of the PtBMA block due to its larger Kuhn length. At φPtBMA 〈 0.30, however, discrepancies are found in the volume fraction dependence of experimentally determined morphological behavior and that calculated theoretically. Interestingly, extremely well-ordered cylindrical microstructures were observed for PI cylinder domains embedded in PtBMA matrices; these samples were prepared by solvent casting with no treatment, such as shearing, to enhance long-range order. These well-ordered cylinder structures contrast with PtBMA cylinders in a PI matrix on the opposite side of the phase diagram that have very poor long-range order. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2629-2643, 1997
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 1365-1371 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An optical fiber probe has been constructed in order to obtain real-time measurements of fluorescence radiation during twin screw mixing and extrusion of plasticized polybutadiene and calcium carbonate particulate. The probe consists of an optical fiber bundle which was inserted along the axis of a half-inch sensor bolt, and it was used to transmit optical excitation energy to the processed material and to detect the subsequent fluorescence. The source of fluorescence radiation was a fluorescent dye which was doped into the processed ingredients at very low concentrations. Although most of our measurements were taken with the probe positioned close to the exit die, the sensor bolt can be placed in any instrumentation port along the extruder line. Experiments were carried out to measure residence time distribution, quality-of-mix, and mix concentrations as a function of processing conditions. Product mix changes in response to variations in material feed rates and screw RPM were also observed. Values of residence time were obtained by measuring the transit times for the dye to travel from an upstream injection port to the measurement probe, a distance of 63 cm. Flow instabilities, such as mat formation of the solids, were observed by noting the abrupt changes and discontinuities in the fluorescence signal.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A capillary rheometer has been designed and built which is capable of making measurements in the shear rate range: 100 s-1 〈 \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm \dot \gamma } $\end{document} 〈 3 × 106 s-1. The rheometer uses the injection unit of an injection molding machine. A modification of this rheometer has been built which consists of two dies in series. Both dies may be used for rheometric purposes, but the second die is intended primarily to act as a valve to allow the mean pressure to be varied in the first die, while keeping the pressure drop constant. In this way the pressure dependence of viscosity may be measured in the injection molding shear rate range. Measurements have been made on unfilled and short glass fiberreinforced polypropylene melts and flow curves covering seven decades of shear rate are presented for the unfilled material. The temperature of the extrudate may be as much as 70°C higher than the barrel temperature. Two effects, shear heating and compression heating, contribute towards this temperature rise, and calculations of the extrudate temperature are in good agreement with measured values. At high shear rates the viscosity is affected by the pressure needed to drive the flow. The effect of pressure on the viscosity outweighs the effect of temperature on the viscosity at high shear rates. A value for the pressure coefficient of viscosity of unfilled polypropylene β = 0.0058 m2 MN-1 has been obtained.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 23 (1985), S. 1057-1061 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of poly(vinylidene fluoride) with several different bases in dimethylformamide solution yields dehydrofluorinated products with conjugated polyene structures. The extent of elimination can be controlled by varying the amount of added base. The structural properties of dehydrofluorinated materials depend on the base used. Polymer films cast from DMF solution exhibit electronic conductivity upon iodine doping; the conductivity is also a function of the base used.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Plant/Operations Progress 7 (1988), S. 87-94 
    ISSN: 0278-4513
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: When handling and processing developmental chemicals for the first time in laboratory, bench scale or pilot plant scale setting, it is important to ascertain the thermal and physical properties of that material early on. Several screening methods for property evaluation are surveyed and the results discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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