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  • Chemistry  (13)
  • AGE; Age, error; Annual layer thickness; Deuterium excess; Dust particles; Greenland; ICEDRILL; Ice drill; International Polar Year (2007-2008); ipy; IPY; NGRIP; North Greenland Ice Core Project; NorthGRIP; Parameter; Sampling/drilling ice; δ18O, water
  • Life and Medical Sciences
  • 1970-1974  (13)
Document type
Keywords
  • Chemistry  (13)
  • AGE; Age, error; Annual layer thickness; Deuterium excess; Dust particles; Greenland; ICEDRILL; Ice drill; International Polar Year (2007-2008); ipy; IPY; NGRIP; North Greenland Ice Core Project; NorthGRIP; Parameter; Sampling/drilling ice; δ18O, water
  • Life and Medical Sciences
  • Polymer and Materials Science  (14)
  • Physics  (2)
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Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Flow visualization for injection molding of polyethylene and polystyrene melts (1974)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 212-222 
    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: Flow patterns have been observed during the injection molding of rheologically characterized low-density polyethylene and polystyrene melts under various molding conditions. Some studies of high-density polyethylene were also carried out. Various mold designs were included in the study and the flow patterns investigated under both isothermal and cold cavity wall conditions. In addition to investigating injection molding of single polymer melts, flow patterns in the sandwich molding of polyethylene and polystyrene were studied.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760140310
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  • 2
    Electronic Resource
    Electronic Resource
    Blocking and copolymer heterogeneity in anionic copolymerization in industrial reactors (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 885-903 
    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: An analysis is given of the effect of reactor design on the variation of composition and extent of blocking in anionic copolymerization. Batch, pipeline, continuous stirred tank (CSTR), and recycle reactors are contrasted. Specifically, alkyl lithium-polymerized butadiene-styrene and alkyl sodium-polymerized p-methylstyrene-styrene are contrasted to the products of copolymerization of the same monomers by free-radical mechanism. It is shown for both systems that considerably more extensive blocking occurs in a batch reactor when the anionic polymerization mechanism is used. The free-radical copolymers, unlike the anionic copolymers, exhibit compositional heterogeneity in a batch reactor. Carrying out the polymerization reaction in a pipeline reactor gives results equivalent to the batch reactor if there is plug flow. However, if a parabolic profile exists in the reactor, there will be significantly increased compositional drift in the copolymer product and a broadened molecular weight distribution, with little effect on blocking. Recycle reactors, including the recirculating loop variety, seem effective in decreasing blocking. The extent of blocking may be considerably decreased in a wellmixed continuous stirred tank reactor. However, poor mixing will greatly increase both the extent of blocking and the compositional heterogeneity of the product.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1972.070160408
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  • 3
    Electronic Resource
    Electronic Resource
    Theoretical analysis and critique of the chromatographic separation of macromolecules using porous adsorbents (1970)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 14 (1970), S. 2723-2729 
    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: A theoretical analysis of the separation of a mixture of macromolecules by a chromatographic column packed with porous adsorbents is given. Fractionation may take place by either exclusion of large molecules from the pores in the column packing or by selective adsorption. A model for packing structure is developed which is used as the basis of a theory of chromatographic separation.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1970.070141106
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  • 4
    Electronic Resource
    Electronic Resource
    An experimental study of adsorption of polymers on activated carbon: Butadiene - styrene polymers and poly(methyl methacrylate) (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 17 (1973), S. 453-469 
    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: An experimental study of the extents and rates of adsorption of several polymers from various solvents onto activated carbon has been carried out. The polymers studied included polystyrene, polybutadiene, butadiene-styrene copolymers and poly(methyl methacrylate). The solvents included toluene, cumene, decalin, 2-pentanone, and methyl ethyl ketone (MEK). Polystyrene is adsorbed from the different solvents in the order MEK, 2-pentanone, cumene, toluene, decalin. The adsorption from toluene, decalin, and cumene is in the order polystyrene, polybutadiene butadiene - styrene copolymer. The fact that the copolymer is adsorbed less than either homopolymer is striking. The variation of molecular weight distribution with extent of adsorption has been studied. It was found that low molecular weight polymer was preferentially adsorbed in the early stages of the experiment, but high molecular weight polymer was adsorbed at longer times. The apparent adsorption rate constants have been evaluated for the various systems and resolved into external mass transfer, internal (intraparticle) mass transfer, and adsorption rate constants. The experimental data have been applied to the prediction of the elution of the polymers from chromatographic columns packed with activated carbon.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1973.070170211
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  • 5
    Electronic Resource
    Electronic Resource
    The influence of carbon black on the extrusion characteristics and rheological properties of elastomers: Polybutadiene and butadiene-styrene copolymer (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 18 (1974), S. 1013-1038 
    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: An experimental study of the influence of carbon black loading, particle size, and structure on the extrusion characteristics of polybutadiene and butadiene-styrene copolymer synthetic rubber is described. The development of extrudate distortion and its mechanisms are considered. The viscosity and die swell have been related to black loading, particle size, and structure. Generally, it is found that black surface area and structure acts to increase viscosity and decrease elastic memory. This situation is analyzed in terms of the theory of nonlinear viscoelasticity. Two mechanistic theories are described which may explain this behavior. One theory is based on the continuum mechanics analysis of suspensions of particles in viscoelastic media. The rheological behavior of the black compounds is explained in terms of the increased severity of deformation in the polymer matrix surrounding the particle agglomerates. The second theory is based on the view of an entanglement network containing black particles. Polymer chains may be adsorbed onto the surface giving rise to increased entanglement densities.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1974.070180405
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  • 6
    Electronic Resource
    Electronic Resource
    Molecular weight distribution and rheological properties of polyisobutylene solutions (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1181-1194 
    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 molecular weight distribution of a series of polyisobutylenes was determined using osmotic pressure measurements, gel permeation chromatography, and intrinsic viscosity. All of the polymers except for one, a blend of the highest and lowest molecular weight constituents, had similar moderate molecular weight distributions. The “extended chain length” method of calibrating the gel permeation chromatograph for polyisobutylenes was found to be effective. Steady state and transient shear stresses and normal stresses were measured on 5% decalin solutions of these polymers. The zero shear viscosity increased with the 3.3 power of molecular weight, and the zero shear normal stress coefficient (σ11 - σ22)/Γ2 varied with the 7.5 power. Relative elastic memory as measured by (σ11 - σ22)/σ12 or stress relaxation increased with increasing molecular weight (and at constant number- or weight-average molecular weight) with breadth of distribution. Stress overshoot also correlated with this tendency.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1971.070150513
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  • 7
    Electronic Resource
    Electronic Resource
    The development of the velocity field in polymer melts in a reservoir approaching a capillary die (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1949-1962 
    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: Color motion pictures have been made of the flow of low-density polyethylene, polystyrene, and isotactic polypropylene at 180°C in the reservoir approach to a capillary extrusion rheometer. Detailed observations of the variation of flow patterns with extrusion rate were made. At low flow rates, essentially radial flow into the capillary entrance was observed in all polymers. With increasing flow rate, the included entrance angle α for the polyethylene and polystyrene decreased from 180°C and a “wine glass” structured velocity field was observed with stagnant circulating regions in the corners and the melt channeling in through the wine glass to the capillary entrance. The angle α was related to entrance pressure drop Δpe and capillary wall shear stress σw data through the semilogarithmic equation \documentclass{article}\pagestyle{empty}\begin{document}$$ \alpha = 178.5\left( {0.9644} \right)^{{{\Delta p_e } \mathord{\left/ {\vphantom {{\Delta p_e } {\sigma _w }}} \right. \kern-\nulldelimiterspace} {\sigma _w }}} $$\end{document} where α is in degrees; Δpe/σw is interpreted as a Weissenberg number. The breakdown of stable laminar flow of the melts in the reservoir and the distortion of extrudates was observed. These phenomena seemed to be initiated by the formation of a spiralling motion in the reservoir.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1971.070150813
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  • 8
    Electronic Resource
    Electronic Resource
    Experimental and theoretical study of the extrusion of two-phase molten polymer systems (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 1313-1330 
    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: An experimental and theoretical study of two-phase flow of molten polymers has been carried out. The theoretical analyses apply the theory of nonlinear viscoelastic fluids to consider stress and velocity profiles and interface shape in stratified flow between parallel plates and in a tube. The second normal stress difference is predicted to influence interface shape. Experimental studies have been made of stratified two-phase flow of a low viscosity but elastic low-density polyethylene and a high-viscosity polystyrene in a capillary rheometer. In the stratified flow experiment, velocity fields and interface shape in the reservoir approaching capillary die and the emerging extrudate were investigated, the former being observed through visual experiments. The emerging extrudates possessed convex polystyrene surfaces at the interface. A strong tendency toward the collection of bubbles near the capillary entry was found. We have made an experimental study of the extrusion of disperse mixtures of polystyrene and different polyolefins. The morphology of the disperse two-phase emerging extrudates has been investigated.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1972.070160601
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  • 9
    Electronic Resource
    Electronic Resource
    Viscoelastic and friction characteristics of polydiene, and butadiene-styrene copolymer tread compounds with application to tire dynamics (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 17 (1973), S. 3273-3292 
    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: An experimental study of the linear viscoelastic and friction properties of passenger tire tread compounds containing realistic black and oil contents and several different types of elastomers including cis-polyisoprene, cis-polybutadiene, emulsion polymerized polybutadiene, and three emulsion polymerized butadiene - styrene copolymers (SBR's) has been carried out. E′ (ω) and tan δ were determined as a function of frequency and temperature. At any specific frequency and temperature, tan δ was an increasing function of Tg or a decreasing function of T - Tg. When the tan δ-frequency data were plotted at the same T - Tg, all of the treads based upon emulsion-polymerized butadiene polymers yielded nearly the same curve. Wet coefficients of friction of the tread compounds correlated with both tan δ and T - Tg supporting the idea that lubricated friction is largely due to hysteresis. The correlation among the butadiene - styrene polymers was much better than with the natural rubber, which exhibits a lower tan δ and a higher wet coefficient of friction than an SBR of the same Tg. The experimental results are used to investigate the heat buildup and skid properties of tires containing these tread compounds.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1973.070171104
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  • 10
    Electronic Resource
    Electronic Resource
    Interaction of melt spinning and drawing variables on the crystalline morphology and mechanical properties of high-density and low-density polyethylene fiber (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 18 (1974), S. 2539-2568 
    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: An experimental study of the spinnability and the variation in crystallinity and orientation in high-density and low-density polyethylene fibers with melt spinning and drawing conditions has been carried out. Three polymers (two high-density and one low-density) and eicosane (C20H42) were studied. The maximum spinnability was in the lower molecular weight high-density polyethylene. Hermans-Stein a, b, and c crystallographic axis orientation factors were computed from wide-angle x-ray scattering patterns. In the spun fiber, small take-up velocities cause the b axis to become perpendicular to the fiber axis in each fiber. The c axis increasingly orients itself parallel to the fiber axis as take-up velocity increases. The a axis orientation is different for each polymer. The results are interpreted in terms of modern theories of crystalline morphology, specifically the development of row structures. In the drawing experiments, the two high-density polyethylenes necked. A phenomenological theory of necking is discussed. The a, b, and c axis orientation factors were determined for different stages of drawing. In the necked regions and in completely drawn fibers, the c axis was parallel to the fiber axis and the a and b axes are perpendicular to the fiber axis. The tangent Young's modulus and tensile strength of the spun fibers increased with take-up velocity and in the drawn fibers were an order of magnitude higher than in the spun fiber. The mechanical properties of spun fiber may be correlated with the c axis (Hermans) orientation factor. The drawn fiber shows significant variations in Young's modulus and tensile strength at constant unit cell orientation.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1974.070180901
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