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  • 1
    Electronic Resource
    Electronic Resource
    Granular magnetic composites employing cobalt based amorphous alloys in a polymeric host : 37th Annual conference on magnetism and magnetic materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 5598-5600 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Cobalt based soft ferromagnetic amorphous alloys have unique properties which make these materials good candidates to be employed in magnetic composites prepared by dispersing granules of the alloy in a polymeric host. These alloys have excellent soft magnetic properties which are minimally affected by external stresses induced during the processing operations involved in the preparation of such a composite. Continuous ribbons of a cobalt based amorphous alloy, Metglas 2705M, were cut into large aspect ratio flakes and blended into a polyethylene host in volume fractions ranging from 0.001 to 0.15. The relative magnetic permeability values of the composites increased with increasing volume fraction of the amorphous alloy, reaching a value of 26 at the volume fraction 0.15. The magnetic properties of the composites exhibited two distinguishing features: The permeability values of these composite samples were found to vary only slightly, about 10%, as a function of frequency in the range 10 Hz–100 kHz; the samples remained unsaturated up to magnetic fields of 5800 A/m. These features are believed to be a result of the magnetic properties of the composite being heavily influenced by the polymeric gaps between the magnetic filler particles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353663
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  • 2
    Electronic Resource
    Electronic Resource
    Thermal behavior and curing kinetics of poly(carbosilane) (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 1087-1095 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: This study focuses on the thermal behavior and curing kinetics of a commercially available poly(carbosilane). Poly(carbosilane) is used for the production of silicon carbide (SiC) fibers by high-temperature pyrolysis. Thermal characterization studies were carried out by employing a differential scanning calorimeter and thermogravimetric analyzer. The change in the chemical structure during curing with oxygen was studied with an infrared spectrometer. It was found that the uncured poly(carbosilane) would froth under a nitrogen environment around 450°C. Curing with oxygen, which results in crosslinking at the surface, enables the sample to retain its shape during high-temperature pyrolysis. Curing was carried out at various temperatures, and the kinetics of the curing reactions were characterized.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420422
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  • 3
    Electronic Resource
    Electronic Resource
    Simulation of intensity of segregation distributions using three-dimensional fem analysis: Application to corotating twin screw extrusion processing (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 1501-1507 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: The corotating twin screw extrusion flow is simulated to generate the distributions of intensity of segregation and integral measures of mixing and forwarding. The simulation focused on the lenticular kneading disk elements that necessitated the application of a three-dimensional finite element method to solve the conservation equations. The intensity of segregation distributions were determined by introducing a tracer blob numerically and tracking the concentration of the tracer particles as a function of location and time. In spite of the chaotic nature of the dynamics of this flow, the analyses provided the broad features of twin extrusion flow and its ability to mix. The processing characteristics of kneading disks were found to depend on the stagger angle and complemented earlier numerical and experimental results on residence time distributions and color incorporated tracer analyses. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070580912
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of surface roughness and the chemical structure of materials of construction on wall slip behavior of linear low density polyethylene in capillary flowBased on a presentation at SPE ANTEC, Detroit (1992). (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 50 (1993), S. 1169-1177 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: The presence of wall slip during the flow of polymeric melts has significant ramifications on the melts' processability. In this study, the effects of materials of construction and surface roughness on the wall slip behavior of a linear low density polyethylene were investigated, using capillary flow. Capillaries, constructed from copper, stainless steel, aluminum, and glass, were used. The inner surface roughness of the capillaries were characterized by the employment of a profilometer and scanning electron microscopy. The roughness profiles of copper capillaries were also altered by the employment of chemical etching. Using Mooney's analysis, the wall slip velocity values were determined to be in the range of 0.09 to 1.34 mm/s. The wall slip velocity values were the highest for stainless steel and were negligible for aluminum. The relative work of adhesion values of polyethylene were the smallest for stainless steel and copper and the highest for glass. Overall, the wall slip velocity values increased with decreasing surface roughness of the capillaries and with decreasing work of adhesion. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070500707
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  • 5
    Electronic Resource
    Electronic Resource
    Measurement and calculation of parison dimensions and bottle thickness distribution during blow molding (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 331-338 
    Details
    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: Experimental data are reported regarding the dynamics of the blow molding process, including parison formation, growth, and inflation. These data have been obtained with the aid of high speed cinematography and pinch mold experiments, in conjunction with two commercial blow molding polyethylene resins. It is shown that pinch mold experiments alone do not yield accurate data regarding thickness and diameter swell. Furthermore, the inflation process involves decreasing rates of inflation with time, as a result of the rise in viscosity due to the cooling of the parison during inflation. Mathematical procedures are proposed for a first-order estimation of parison length and swell as a function of time and the inflation behavior after clamping. In the absence of more dependable basic procedures, the proposed treatment is employed to estimate the effective transient swell functions for the parison using experimental data obtained under the specified conditions. The mathematical treatment is extended to determine the thickness distribution of the bottle. Good agreement is obtained between experimental and calculated results.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760210604
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  • 6
    Electronic Resource
    Electronic Resource
    Simulation of microstructure development in injection molding of engineering plastics (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 477-489 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Mathematical models were developed to predict the various microstructural properties, including birefringece, residual stress, and density distributions, in the freely quenched compression molded samples as well as in the injection molded samples. To model the birefringence distribution in the injection molded samples, the BKZ type integral constitutive equation was employed to account for the nonisothermal stress relaxation, which takes place during the cooling stage of the molding cycle. The predicted birefringence agreed well with the experimental data near the mold walls. The residual stress distribution was modeled by the existing thermoelastic theory. The residual thermal stress distribution in the freely quenched samples was predicted very well by the model. However, the predicted residual thermal stresses in the injection molded samples were much larger than the measured ones. A phenomenological model to predict the density distribution in injection molded sample is proposed by including the effects of both cooling rate and the pressure on the density development. The predicted results agreed well with the experimental data.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070440313
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  • 7
    Electronic Resource
    Electronic Resource
    Heat transfer and microstructure in extrusion blowmolding (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 503-509 
    Details
    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: Experimental measurements were made to determine the contact temperature and the rate of heat transfer between the mold and the polymer during the cooling stage of the extrusion blowmolding process. The experimental data were compared to the results of a finite difference computer simulation of the heat transfer problem, allowing for the variation of the properties of the polymer in the solid and molten states. Good agreement was obtained between experimental and calculated results. Heat transfer results were subsequently employed to explain observed differences in the microstructure of the blowmolded articles, particularly in relation to the distributions of crystallinity and birefringence. Finally, it was demonstrated that much faster cooling rates and more uniform molded articles can be obtained by employing rapid internal cooling, as in the case of water injection into subzero air inside the inflated parison.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760230905
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of air entrainment on the rheology of concentrated suspensions during continuous processing (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 1386-1392 
    Details
    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: Samples of a concentrated suspension were systematically collected from the mixing volume of a continuous processor. The large amplitude oscillatory shear behavior of the samples was found to be significantly affected by the screw configuration employed and the location. Microstructural analyses employing nuclear magnetic resonance imaging, wide-angle X-ray diffraction and X-ray radioscopy revealed substantial entrainment of air into the suspension during continuous processing. The volume fraction of the entrained air increased with geometries and operating conditions leading to partially full channels. Overall, air entrainment is identified as a dominant factor in the development of the microstructure and the rheology of concentrated suspensions and should be considered in their optimum processing.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760311904
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  • 9
    Electronic Resource
    Electronic Resource
    Development of cracks in injection moldings of poly (2,6-dimethyl-1, 4 phenylene ether) (1991)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 1393-1399 
    Details
    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: Cracks in injection molded articles adversely affect their appearance as well as their ultimate properties. In this study, we have investigated the spontaneous development of cracks in samples molded from an engineering plastic in the absence of external loading. The specimens of a well characterized poly(2,6-dimethyl-1,4 phenylene ether), PPE, were injection molded employing a 40t Van Dorn injection molding machine and industrial practices. The initiation and development of cracks in the molded articles were monitored for a period of eighty weeks. The presence and the frequency of the cracks were found to depend on the operating conditions employed during the molding, the shape of the cavity, the presence of Irregularities at the mold surface, and the particular location observed. The results were elucidated under the light of the results of microstructural analyses including residual stress and birefringence distributions on both compression and injection molded specimens of the engineering plastic.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760311905
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  • 10
    Electronic Resource
    Electronic Resource
    Mechanisms of mixing in single and co-rotating twin screw extruders (1995)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 1325-1338 
    Details
    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: Previous experimental studies have revealed that the mixing efficiencies of widely used continuous processors such as the single and twin screw extruders depend on the types of screw elements, which are utilized. It is generally recognized that the basic single screw extruder and the fully-fighted sections of the fully-intermeshing co-rotating twin screw extruders are not efficient mixers, in contrast to the specialized mixing elements such as the kneading discs used in co-rotating twin screw extruders. However, no simulation techniques were available to characterize quantitatively and rigorously the mixing efficiencies of continuous processors. In this study, we have solved the three-dimensional equations of conservation of mass and momentum, and utilized various tools of dynamics to analyze the mixing occurring in single and co-rotating twin screw extruders. It is shown that simulation methods can indeed capture the relative differences in the mixing mechanisms of continuous processors like the single and twin screw extruders. The ability to distinguish quantitatively between the distributive mixing capabilities of various continuous processors should facilitate numerical testing of new continuous mixer designs, optimization of operating conditions and geometries of existing mixers and the material-specific design of new mixers.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760351702
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