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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 37 (1989), S. 2295-2312 
    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 effect of mixhead geometry on the impingement mixing in the reaction injection molding (RIM) process is largely unknown. In this study, high speed photographs are used to show the flow patterns produced by L shape mixheads. The mixing quality of the conventional I and various L shape mixheads is quantified by an emulsion test. The adiabatic temperature rise of a polyurethane/urea system is followed to further characterize the mixing produced by I and L shape mixheads. The results show that L shape mixheads give a better mixing quality than the I shape mixhead, especially at lower Reynolds numbers. In addition, the L shape mixheads can provide a more laminar flow from the mixhead, which is important for mold filling.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 37 (1989), S. 2313-2330 
    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: A high pressure differential scanning calorimeter (DSC) and a Fourier transform infrared (FTIR) spectrometer with a prism liquid cell (PLC) were used to monitor the reaction kinetics of styrene-unsaturated polyester resins at elevated curing temperatures and pressures. The thermal method is easy to perform but provides only an overall reaction exotherm. The spectroscopic method can detect the detailed reaction mechanism of copolymerizations. It is, however, less quantitative and the calculation is much more time-consuming compared to the thermal analysis. Reactions of two unsaturated polyester resins with different molecular structure were measured by these two methods. Results showed that applying cure pressure on unsaturated polyester resins reduced the reaction rate but increased the final conversion. The styrene reaction was enhanced more than the polyester reaction at high curing temperatures.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 33 (1987), S. 793-807 
    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: A series of polyurethane-polyester simultaneous interpenetrating network (SIN) samples were prepared by a laboratory-scale transfer mold. The effect of compound composition and molding conditions on the tensile properties and crystallinity of molded parts was examined by using an Instron tensile tester and a Perkin-Elmer differential scanning calorimeter (DSC). It was found that incomplete polymerization resulted in a poor tensile strength of 80°C-molded SIN. Postcure treatment and higher molding temperature increased the tensile strength of SIN by improving their limiting conversion and possibly the morphology. Results indicated that postcure was more efficient than molding at higher temperature for SIN samples with high polyurethane content. On the other hand, for SIN with higher polyester content, a high molding temperature resulted in better mechanical properties than postcuring the low-temperature molded samples. Both reaction sequence and cross-linking nature of the constituent polymers had a profound effect on the tensile properties of SIN.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 33 (1987), S. 431-453 
    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: An experimental study of temperature effect and composition effect on the rheological and extrusion properties of several dispersed multiphase polymer melts were investigated, using a cone-and-plate rheometer and a capillary rheometer. The polymeric systems studied included three homopolymers (two polystyrenes and one poly(methyl methacrylate) (PMMA)), a mechanically blended copolymer of polystyrene and PMMA, two graft copolymers (rubber-modified polystyrene and PMMA), and three particulate-filled polystyrene (CaCO3, milled glass fiber, and glass flake). It was found that the principal normal stress difference plotted against shear stress gives rise to a temperature independence for all dispersed multiphase polymeric systems. Composition independent correlations, however, do not exist for the principal normal stress difference. The extrudate swell plotted against shear stress becomes independent of temperature only for the homopolymers and graft copolymers. For the mechanically blended polymers and particulate-filled polymers, the temperature independent correlation does not exist. The reduction in viscosity of the glass fiber- and glass flake-filled polystyrenes is found due to the degradation of the base polymer during mixing.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 33 (1987), S. 1315-1341 
    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 paper is concerned with applications of a kinetic-diffusion model which accounts for the gel effect and glass effect for free radical polymerizations under nonisothermal conditions. Bulk polymerizations of styrene and unsaturated polyester in the batch casting process were investigated both experimentally and theoretically. A differential scanning calorimeter (DSC) and a Fourier transform infrared spectrometer (FTIR) were employed to elucidate incomplete reactions resulting from glass transition and dead-ending phenomena and to provide kinetic information for modelling. Temperature, conversion, and cumulative molecular weight profiles were simulated under several wall temperature programs. Predictions of ultimate cumulative molecular weights across the reactor, when compared with experimental results measured by gel permeation chromatography (GPC), affirmed that the molecular weight variation due to the radial temperature gradient could be alleviated by manipulating the wall temperature.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 16 (1990), S. 471-471 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 17
    ISSN: 0730-6679
    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
    Notes: Analysis of a plastic sheet extrusion line was carried out using a 2.5-in. extruder in conjunction with a three-roll stack system for processing of both poly(methyl methacrylate) (PMMA) and high-impact polystyrene (HIPS). Tests conducted include dynamic responses, sheet cooling behavior, velocity and thickness profiles, and frozen-in strain measurements. Experiments with PMMA were also performed on an extrusion-air cooling line to provide a basis for comparison with the extrusion-roll stack system. The results showed that the size and stability of the bank in the extrusion-roll stack system affected the thickness variations and the frozen-in strains. Operating the roll stack system was found to allow for fairly rapid rearrangements from parabolic to plug velocity profiles. Line comparisons between the roll stack and air cooling showed that the roll stack minimized thickness variations, frozen-in strains, and surface flaws.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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