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  • 1
    Electronic Resource
    Electronic Resource
    Combined use of immunocytochemical techniques and ligand-gold complexes for investigation of platelet membrane responses to surface activation (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 28 (1994), S. 308-326 
    Details
    ISSN: 1059-910X
    Keywords: Glycoproteins ; Spread cells ; GPIIb-IIIa ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Exposure of blood platelets to foreign surfaces results in dramatic changes in physical appearance and conversion from a non-sticky to an adhesive state. Membrane glycoproteins and cytoskeletal assembly play a pivotal role in these interactions. Cytochemical techniques commonly applied for demonstration of macromolecules in tissues have been used for the localization of target glycoproteins on spread cells. The present review examines different experimental strategies and immunocytochemical techniques that can be combined to better understand the organization of platelet receptors during surface activation. Glycoprotein IIb-IIIa (GPIIb-IIIa) was localized by immunocytochemical techniques on fixed, surface-activated platelets. The distribution of functional fibrinogen receptors expressed on GPIIb-IIIa was revealed by incubation of fixed platelets with fibrinogen-gold conjugates (Fgn/Au). The movement of receptor complexes was investigated in additional experiments in which surface-activated platelets were interacted with Fgn/Au and then fixed at different periods. The overall impression of these observations suggests that fibrinogen receptors on surface-activated platelets do not redistribute spontaneously and that particulates (gold particles), rather than fibrinogen, may trigger the movement. These results are presented in detail and their significance discussed in the light of current theory. Applications and limitations of such techniques are also discussed. © 1994 Wiley-Liss, Inc.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070280407
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  • 2
    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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  • 3
    Electronic Resource
    Electronic Resource
    The influence of drawing, twisting, heat setting and untwisting on the structure and mechanical properties of melt spun polypropylene filament (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 761-773 
    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 changes in structure and mechanical properties of melt spun polypropylene filaments were determined as the filaments were successively (i) drawn, (ii) twisted, (iii) annealed, and (iv) untwisted. Filaments spun to two different melt draw down levels were studied. The effects of draw temperature and draw ratio, extent of twist, annealing temperature, and the extent of untwisting were examined. Melt spun and twisted filaments (draw ratio of 1) were also considered. Structural characterization techniques used in this study include wide angle (WAXS) and small angle (SAXS) diffraction, scanning electron microscopy (SEM), birefringence and density measurement. Drawing increased crystalline orientation and at low temperatures disrupted the monoclinic unit. cell existing in the melt spun fibers. The drawing produced considerable fibrillation under all conditions even when carried out at 120°C. The fibrillation quid void formation due to low temperature drawing was more pronounced. The variation of WAXS patterns and mechanical properties of twisted drawn filaments was interpreted by presuming that the fibrils act in a manner analogous to that of the filaments in a continuous filament twisted yarn. In the case of incompletely drawn filaments the effect of additional drawing occurring during twistin must be considered. Twisted fibers annealed at 150°C sowed a drastic reduction in tensile properties, while those annealed at 125°C did not set the twist and caused the fibers to tend to untwist. Annealing at 140°C appeared to give satisfactory heat setting. Annealing of cold drawn and cold drawn and twisted fibers increased the density, removed many defects and reformed a well defined monoclinic crystal structure and a lamellar morphology. Untwisting of heat set filaments tended to give back the properties of hot drawn fibers. In some cases, however, the opening of cracks was noted.
    Additional Material: 30 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760191102
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  • 4
    Electronic Resource
    Electronic Resource
    The specification of orientation and its development in polymer processing (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 247-256 
    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 critical review of the specification of orientation and its development in polymer-processing operations is presented. Orientation may in general be specified by orientation distribution functions, but is most conveniently expressed in terms of orientation factors which are second moments of the distribution. The Hermans orientation factor represents polymer-chain orientation for systems with fiber symmetry (uniaxial orientation) and the Hermans-Stein orientation factors express uniaxial orientation for each of the crystallographic axes of crystalline polymers. Biaxial orientation is, however, developed in tubular film extrusion, blowmolding and, indeed, all processing operations other than fiber formation. Orientation factors developed previously by the authors express biaxial orientation in terms of the angles between the machine and transverse directions and the polymer chain axis or crystallographic axes. In flowing polymer melts, the Rheo-Optical Law, which relates birefringence and stress, represents a relationship between polymer-chain orientation and stress. In vitrified polymeric glasses (e.g. polystyrene), the orientation factors are related linearly to the stress field at vitrification. This has been shown experimentally for melt spinning and tubular film extrusion. The results of studies of blowmolding and injection molding are consistent with this. The crystalline orientation factors have also been found to be determined by the stress field at solidification in melt spinning and tubular film extrusion.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760230503
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  • 5
    Electronic Resource
    Electronic Resource
    Poly(p-phenylene terephthalamide) films formed from extrusion and coagulation of liquid crystalline sulphuric acid solutions: Characterization of orientation and void structure, annealing, and upgrading of film mechanical properties (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 242-251 
    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: Poly(p-phenylene terephthalamide) (PPD-T) films have been prepared by continuous extrusion of liquid crystalline 17 percent PPD-T/sulphuric acid solutions through an annular die followed by coagulation, Films extruded without drawdown exhibit some polymer chain orientation in the machine direction. This is increased by uniaxially drawing down films. Films produced with a lubricated conical mandrel sitting between the die and the coagulation bath exhibit an equal biaxial orientation. The uniaxially oriented films exhibit highly anisotropic mechanical properties, while the mandrel-produced film exhibits balanced properties. Heat treatment at 350°C results in significant enhancement of the tensile strength of the mandrel film. Void structures in the films have been investigated by mass density, scanning electron microscopy (SEM), and small-angle X-ray scattering (SAXS). Density measurement indicate a void content decreasing with decreasing film thickness and heat treatment. SEM locates micron-size voids in the thickest films, apparently caused by rapid coagulation. SAXS indicates much smaller void sixes which are roughly prolate ellipsoids (long axis in machine direction) for uniaxial films and oblate ellipsoids (short axis in thickness direction) for the mandrel produced films. Various techniques are used to estimate mean void size.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240403
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  • 6
    Electronic Resource
    Electronic Resource
    An investigation of optical clarity and crystalline orientation in polyethylene tubular film (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1035-1042 
    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 study of the crystalline orientation, light transmission, and surface roughness of polyethylene tubular film prepared in our laboratories is presented. The present studies were primarily carried out on low-density (LDPE) and linear-low-density (LLDPE) polyethylene films. The optical properties of a few films of high-density polyethylene (HDPE) prepared for a previous study of morphology were characterized for comparison to the LDPE and LLDPE films. Wide angle X-ray diffraction and birefringence were used to characterize orientation. Both the LDPE and LLDPE films exhibited crystalline texture in which the b-axes tended to be perpendicular to the film surface and the a-axes had some tendency to align with the machine direction. The c-axes tended to be concentrated in the plane of the film with nearly equal biaxial orientation with respect to the machine and transverse directions. Little variation in the crystalline orientation was found with changes of process conditions in the range studied. Birefringence results indicate that the amorphous regions developed an orientation in which the chains tend to be normal to the film surface. The majority of light scattering from these films and a series of HDPE films was from the surface and not from the film interior. The transmission coefficient for the surface contribution was found to be a monotonic decreasing function of the standard deviation of the surface height obtained from surface profiles measured by profilometer. The surface asperites were largest for the HDPE and smallest for the LDPE samples. The intensity of both the surface and interior contributions to the scattering increased with increasing frostline height, i.e., a slower cooling rate. As draw-down ratio and blow-up ratio increase the scattering contribution from the film interior decreases but the contribution from the surface increases somewhat. These effects are discussed in terms of the changes in crystalline morphology and surface roughness produced by flow defects generated during extrusion.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241307
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  • 7
    Electronic Resource
    Electronic Resource
    Kinematics, dynamics and stability of the tubular film extrusion of various polyethylenes (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1185-1201 
    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 basic study of the kinematics, dynamics, and heat transfer occuring during tubular film extrusion of polyethylene is outlined. Three rheologically characterized polyethylenes, a low-density polyethylene (LDPE), a linear-low-density polyethylene (L-LDPE), and a high-density polyethylene (HDPE) were used in this study. The kinematics and stability of the tubular film process were investigated over a wide range of blow-up ratios, drawdown ratios, and frost-line heights. Local deformation rates along the bubble have been determined. Regions of stability and instability are described. Tensions and inflation pressures have been measured and expressed in terms of locol elongational viscosities. Temperature profiles along the bubble were determined and interpreted in terms of local heat transfer coefficients. Positions of crystallization and temperature profiles have been noted and used to estimate rates of crystallization. The characteristics of the LDPE, LLDPE, and HDPE are contrasted.
    Additional Material: 47 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241508
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  • 8
    Electronic Resource
    Electronic Resource
    Development of phase morphology in incompatible polymer blends during mixing and its variation in extrusionThe experimental studies described were carried out at the University of Tennessee as part of the Ph.D. Dissertation of K. Min. (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1327-1336 
    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: An experimental study of the development of phase morphology in incompatible polymer melt blends of polyethylene/polystyrene (PE/PS), polyethylene/polycarbonate (PE/PC), and polyethylene/nylon-6 (PE/N6) is presented. Different temperatures (180°C, 240°C) of mixing and polyethylene molecular- weight levels were used in the PE/PS studies. Little variation in the cross-sectional phase morphology of the PE/PS extrudates was observed with these variables, though the morphology became finer with increased shear rate/stress in capillary die flow. Variations in the longitudinal morphology are observed with continuous filaments of dispersed phase only arising when the dispersed phase has an equal or lower viscosity than the continuous phase. The PE/N6 and PE/PC, especially the former, give coarser morphologies when the N6 and PC are the continuous phases. This was attributed to larger inter-facial tensions. The effect of viscoelasticity was also discussed.
    Additional Material: 24 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241710
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  • 9
    Electronic Resource
    Electronic Resource
    Polyethylene-polycarbonate blends: Interface modification, phase morphology and measurement of orientation development during cast film and tubular extrusion by infrared dichroism (1986)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 26 (1986), S. 45-53 
    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 phase morphology and polymer chain orientation in polyethylene-polycarbonte blends is investigated. A blend with a dispersed polyethylene phase was found to exhibit phase growth under quiescent conditions. Addition of a styrene-(ethylene/butene) block copolymer controls the phase morphology and prevents phase growth. Melt spun tapes and tubular film have been prepared from polyethylene-polycarbonate blends. Orientation of the crystallo-graphic axes of the polyethylene and the chain axis of the polycarbonate were determined by infrared dichroism. The addition of polycarbonate to polyethylene is found to decrease chain orientation at the same drawdown stress.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760260109
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  • 10
    Electronic Resource
    Electronic Resource
    An investigation of instability of phase morphology of blends of nylons with polyethylenes and polystyrenes and effects of compatibilizing agents (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 69-80 
    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: Investigations of instability of phase morphology of blends of nylons with polyethylenes and polystyrenes and the effects of “compatibilizing” additives or “agents” are described. Annealing coarsens the phase morphology of blends of nylons with polyethylenes and polystyrenes. Phase growth is observed for various periods of annealing time. The addition of compatibilizing agents, specifically maleic anhydride grafted polyolefins to polyethylene-nylon blends and syrene-maleic anhydride copolymers to polystyrene-nylon blends, stabilize the phase dimensions. Styene-maleic anhydride copolymer is found more effective than styrene acrylonitrile copolymer as a compatibilizing agent. The mechanisms of this behavior are critically discussed.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760280203
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