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  • 1
    Electronic Resource
    Electronic Resource
    Radiation-induced crosslinking: III. Effect on the crystalline and amorphous density fluctuations of polyethylene (1991)
    Springer
    Colloid & polymer science 269 (1991), S. 353-363 
    Details
    ISSN: 1435-1536
    Keywords: Crosslinking ; radiation ; polyethylene ; density ; crystallinity ; phasedensities ; densityfluctuation ; phasedensityfluctuations ; Crosslink locations and mechanisms ; defects ; lateral grainboundaries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Small-angle x-ray scattering (SAXS) was used to determine density fluctuation in radiation-induced crosslinked polyethylene of varying degrees of crystallinity. Density fluctuation FL decreases with increasing crystallinity, while it increases linearly with increasing radiation dose or degree of crosslinking. By means of extrapolation, density fluctuations in the crystalline and the amorphous phasesFL c andFL a were obtained. At a given dose,FL a is greater thanFL c . The increase inFL a with radiation is found to be much greater than that ofFL c compared with the initial values at 0 Mrad,FL c showing only a negligible increase event at 312 Mrad. The present findings suggest that crosslinks are not introduced within the crystalline phase; they take place primarily in the noncrystalline phase, in agreement with the conclusions reached previously on the basis of changes in crystalline and amorphous densities in irradiated polyethylene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00654582
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  • 2
    Electronic Resource
    Electronic Resource
    CPS K 843 Radiation-induced crosslinking: Effect on structure of polyethylene (1985)
    Springer
    Colloid & polymer science 263 (1985), S. 109-115 
    Details
    ISSN: 1435-1536
    Keywords: Crosslinking ; radiation ; polyethylene ; density ; crystallinity ; d-spacings ; phase densities ; crosslink locations ; lateral grain boundaries ; crosslink mechanisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Branched polyethylene irradiated (0–400 Mrad) with a Co60 source at room temperature under vacuum was studied by density, wide- and small-angle X-ray scattering (WAXS and SAXS) measurements. The radiation effects on the structure of bulk, branched polyethylene are quite similar to those observed by others on single crystals or oriented preparations. These effects include changes in bulk densityϱ, crystallinity(w c orv c) and¯d 100 and¯d 200 spacings as a function of irradiation. A decrease in crystallinity is seen to begin at radiation dose ≈100 Mrad whereas lattice expansion indicating onset of an orthorhombic-hexagonal transition can begin as low as 10 Mrads. The decrease in crystallinity can be attributed to additional lattice distortions primarily introduced by the crosslinks occurring at the lateral grain boundaries, while lattice expansion can be associated with the same crosslinking mechanism which begins at the defects both within the crystals as well as those outside the crystals at the lateral grain boundaries. Strong evidence for a primary crosslinking-at-the-defects mechanism has also come fromϱ c andϱ a data obtained in this study as a function of radiation dose. The same data have also led to an excellent correspondence between the measured density crystallinityv c and the measured WAXS crystallinityw c. Without consideration of the effects of crosslinks onϱ c andϱ a one would have obtained a divergence of the two crystallinities, especially at radiation doses greater than 100 Mrads.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01412784
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  • 3
    Electronic Resource
    Electronic Resource
    Radiation-induced crosslinking: II. Effect on the crystalline and amorphous densities of polyethylene (1991)
    Springer
    Colloid & polymer science 269 (1991), S. 469-476 
    Details
    ISSN: 1435-1536
    Keywords: Crosslinking ; radiation ; polyethylene ; density ; crystallinity ; d-spacings ; phase densities ; crosslink locations and mechanisms ; defects ; lateral grain boundaries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Small-angle x-ray scattering (SAXS) was used to determine the structural changes in polyethylene induced by radiation. The changes in densities of the crystalline and amorphous phases, ρ c and ρ a , were calculated after direct determination of the mean square density fluctuation 〈η2〉. ρ a increases with increasing radiation dose for both linear and branched polyethylene. This accounts for the serious discrepancy between crystallinities determined from wide-angle x-ray scattering and density measurements. This study confirms our previous proposal that crosslinks occur primarily in the noncrystalline phase, most likely at the defects in the lateral grain boundary regions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00655884
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  • 4
    Electronic Resource
    Electronic Resource
    Turbulence closure modeling of the dilute gas-particle axisymmetric jet (1986)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 32 (1986), S. 163-166 
    Details
    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
    URL: http://dx.doi.org/10.1002/aic.690320121
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  • 5
    Electronic Resource
    Electronic Resource
    Computer model for tubular high-pressure polyethylene reactors (1976)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 22 (1976), S. 463-471 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A computer model was developed for tubular high-pressure polyethylene reactors. Plug flow and absence of axial mixing were assumed. Emphasis was placed on realistic modeling of the reaction kinetics and the variation of physical properties along the reaction coordinate. A good simulation of axial temperature profiles, conversion, molecular weights, molecular weight distribution, and transport properties along the reaction coordinate is believed to have been achieved. The model can be extended readily to cases where radial diffusion is significant.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690220308
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  • 6
    Electronic Resource
    Electronic Resource
    Influence of rubber content on static and dynamic properties of polystyrene (1989)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 69-76 
    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: Mechanical properties, deformation modes under both uniaxial tension and compression, low temperature mechanical relaxation behavior, and resistance to fracture under dynamic loading have been investigated for a medium impact grade of polystyrene, Shear yielding is the dominant mode of plastic deformation in compression while matrix crazing, together with some tearing and cavitation of the rubber phase, occurs in tension. The craze microstructure, as determined by transmission electron microscopy (TEM), is typical of that noted in polystyrene, with sharp craze-bulk interfaces and a characteristic midrib section. The presence of a third phase, possibly a processing aid, is evident in the TEM scans and in the dynamic mechanical data. The present data, together with the data obtained on polystyrene and on high impact polystyrene, are used to show the strong influence of rubber content on various mechanical properties, such as the tensile craze yielding stress, ductility, compression yield strength, degree of strain softening, and fatigue durability.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760290112
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  • 7
    Electronic Resource
    Electronic Resource
    Environmental effects of silicone oil on tensile and fatigue properties of polystyreneOral presenting made at Symposia on “Polymer Fatigue and Non-Linear Behavior,” Organic Coatings and Plastics Chemistry Division, ACS Meeting, New York, Aug, 1981 (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 451-456 
    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: A series of polished polystyrene specimens, coated with silicone oil, were tested in tension and in tension-compression fatigue cycling at 21 Hz. Oils of four different viscosities, ranging from 5 cSt to 1000 cSt, were utilized. The craze initiation stress and the tensile fracture stress both increased with the increase of oil viscosity. For the 1000 cSt oil, the stress-strain curve was essentially the same as that of an uncoated sample. The average lifetime to fracture in the fatigue tests depends upon the stress amplitude and on the oil viscosity. For the 1000 cSt oil, the fatigue behavior is similar to that of uncoated samples, except at high imposed stresses, where lifetime is somewhat lower. For the low viscosity oil, the average lifetime is from one to two decades less than for uncoated samples. Discussion is given of the influence of stress amplitude and oil viscosity on the test results and on the morphology of the fracture surfaces.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760220710
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  • 8
    Electronic Resource
    Electronic Resource
    Deformation modes and fatigue behavior in styrene-acrylonitrile and acrylonitrile-butadiene-styrene copolymers (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 786-797 
    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: The performance of styrene-acrylonitrile copolymers under alternating stresses has been examined. Information has been obtained concerning the influence of acrylonitrile content and of molecular weight on thermal effects due to hysteresis, on cyclic lifetime to craze initiation, on average cycles to fracture, and on fatigue fracture surface morphology. The influence of an elastomeric second phase has been determined by comparing fatigue performance under comparable conditions of both styrene-acrylonitrile (SAN) and acrylonitrile-butadiene-styrene (ABS). The stress concentrating effects of the rubber particles cause earlier initiation of fatigue-induced damage and lower fatigue fracture resistance. The fatigue-induced specimen temperature rise is greater in ABS than SAN and it increases linearly with test frequency and as the square of the stress amplitude. The fracture surface morphology of ABS, which differs from that of unmodified SAN and also from that of rubber modified polystyrene, is discussed.
    Additional Material: 25 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241008
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  • 9
    Electronic Resource
    Electronic Resource
    Flow of thermoplastics in an annular die under parallel oscillations (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1574-1584 
    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: A sound wave extrusion system has been developed. This system includes a single screw extruder and an annular die having an internal surface oscillating in the sound frequency range. Oscillating shear flow has been imposed in the direction parallel to the main pressure flow. The die characteristics and average melt temperature at the exit from the die for several thermoplastics have been measured with and without imposition of oscillations. Modeling of parallel superposition of sound oscillations upon pressure flow has been performed using the Leonov viscoelastic constitutive equation. Three cases are considered: (i) the process is isothermal and the change in die pressure is only due to a nonlinear interaction of oscillatory and pressure flow; (ii) the process is nonisothermal and adiabatic, and pressure reduction is due to the nonlinear interaction and the dissipation of oscillatory energy leading to the temperature rise in polymer melts; (iii) the process is nonisothermal with heat transfer due to transient heat conduction and the dissipation of oscillatory energy. Pressure reduction occurs due to both nonlinear interaction and temperature rise. It is found that case (i) cannot explain the observed die pressure reduction, while case (ii) describes those data only at high flow rates. The theoretical results from case (iii) are found to be in qualitative agreement with experimental observations. Generally, the theoretical results of case (iii) are better than those of cases (i) and (ii).
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760302404
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  • 10
    Electronic Resource
    Electronic Resource
    Processability and thermal properties of blends of high density polyethylene, poly (ethylene terephthalate), and ethyl vinyl acetate compatibilizer (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 472-476 
    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: Because of differences in chemical structure and rheological characteristics, high density polyethylene (HDPE) and poly(ethylene terephthalate) (PET) are incompatible when blended during recycling of PET soft drink bottles. To improve the properties of the blends, ethylene vinyl acetate copolymer (EVA) was used as a compatibilizer. Based on torque rheometer tests, the higher the concentration of PET in the blends, the higher the initial loading torque. Blends of 50% HDPE and 50% PET had the lowest equilibrium torque. Equilibrium torque was highest at 5% EVA. The presence of EVA made only a slight difference in the glass transition temperatures of HDPE/PET blends. Higher EVA content in the blend resulted in a lower melting endotherm. Thermogravimetric analysis showed that thermal stability was independent of EVA content; but the more PET in the blend, the lower the final weight loss.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760340603
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