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  • Digitale Medien  (84)
  • Chemistry  (83)
  • 61.16.Bg  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Crystal and electronic structure of solid C76 (1994)
    Springer
    The European physical journal 95 (1994), S. 469-474 
    Details
    ISSN: 1434-6036
    Schlagwort(e): 79.20.Kz ; 61.46.+w ; 61.16.Bg
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The crystal and electronic structure of solidC 76 has been studied using transmission electron microscopy and electron energy-loss spectroscopy in transmission. C76 forms a close packed structure with an average facecentred cubic symmetry. From valence band and core electron excitations information on the dielectric function and the unoccupied density of states has been obtained.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01313354
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  • 2
    Digitale Medien
    Digitale Medien
    Interfacial interactions and mechanical properties of filled polymers (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 40 (1990), S. 1783-1794 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Mechanical properties, notably the ductility of rutile-filled low-density polyethylene (LDPE) and chlorinated polyethylene (CPE), were studied to determine the influence of filler dispersion and of matrix-filler interactions. Potential interactions between polymer and filler were obtained from inverse gas chromatography, in the form of acid/base interaction parameters. The strength of filler aggregates was obtained from flow properties of the dry powders. Dispersion quality in molded specimens was identified from X-ray contact micrographs. The ductility of filled, nonpolar LDPE was found to be independent of acid/base considerations, but strong correlations have been drawn between the strength of filler aggregates and the quality of dispersion attained by controlled mixing methods. Inherent filler agglomeration thus also affects the mechanical properties of the nonpolar matrix. Coated, nonagglomerated fillers dispersed well, leading to ductilities at low filler load that exceeded that of the unfilled host polymer. In contrast, acid/base interactions were found to exert dominant influence on rutile dispertion in CPE. Similarly, the mechanical properties of this polymer varied with the acid/base forces acting at matrix/filler contacts.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1990.070400931
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  • 3
    Digitale Medien
    Digitale Medien
    Inverse gas chromatographic study of polymer blend interactions and their temperature dependence (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 787-796 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The temperature dependence of the thermodynamic interactions in blends of polypropylene and a fluorochemical was studied by inverse gas chromatography (IGC). A modified procedure has been proposed to evaluate the effective surface composition in polyblends. This shows that the low surface energy component preferentially concentrates in the surface region of blends. Moreover, the new procedure greatly reduces the probe-to-probe variation of χ23, a problem frequently encountered in thermodynamic applications of the IGC method. As a result, IGC may now be used with increased confidence for the determination of interaction thermodynamics in polymer systems over broad temperature ranges. © 1992 John Wiley & Sons, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1992.070460506
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  • 4
    Digitale Medien
    Digitale Medien
    Aspects of surface characterization of polyurethane adhesives (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 52 (1994), S. 1857-1865 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The performances of adhesives is strongly dependent on the contributions to overall surface energies from dispersion and nondispersion forces. In this work, surface energies have been studied for polyurethanes representing the categories of aliphatic and aromatic polyethers and aliphatic polyesters. The surface energies of the polymers were measured by static and dynamic contact angle methods. In addition to determining the energy values for polymers as received, evaluations were also made on the polymers following modification by an aminopropyl silance (APS), present at concentrations ranging from 0.1 to 20 wt %. The dispersion surface energies of the three polymers were roughly equal; however, the nondispersive surface energies strongly differentiated among them. Organic liquids were used for calculations of energy parameters from static contact angles. Data for water failed to follow theoretical expectations and were used instead to compute a work of adhesion parameter for the polymer/water interface. This correlated with nondispersion surface energies of the polyurethanes. Somewhat different values of the nondispersion surface energy were obtained from static and dynamic contact angles, an effect attributed to the tendency of polyurethanes to restructure when their surfaces were in prolonged contact with water during dynamic analysis. This behavior may be important to the type of adhesive bond formed by the polymers and to variations in bond characterstics with time. The use of APS was found to influence both static and dynamic contact angle values, with primary changes occuring in nondispersion contributions. The effects of APS addition were fully developed at concentrations of 1 wt % or less, raising doubts about the efficiency of using this additive at higher concentrations. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1994.070521303
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  • 5
    Digitale Medien
    Digitale Medien
    Polyethylene flow data from melt viscometer and commercial extruder measurements (1961)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 1 (1961), S. 86-92 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: For broad ranges of operating conditions and a wide variety of high pressure polyethylenes, the flow data obtained from a high shear viscometer and a commercial extruder are identical. Discrepancies between flow data can result from non steady state viscosities in the high shear viscometer, or from cooled screw extruder operation. In the broad regions in which the flow data concur, the readily obtained viscometer data are suitable for predictions of extruder performance. The principle is illustrated by the good correlation of a viscometer flow curve parameter and the screw power consumption in the extruder. Principles outlined for flow data identity and extruder performance prediction are believed to be general, but the quantitative limits defined are specific to the extrusion devices involved.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760010209
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  • 6
    Digitale Medien
    Digitale Medien
    Introductory remarks (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 433-433 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760170702
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  • 7
    Digitale Medien
    Digitale Medien
    Adhesion at polypropylene-cellophane interfaces (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 456-461 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The shear strength of bonds between isotactic polypropylene and cellophane, formed under standard conditions, has beer studied as a function of cooling rates, following bond formation, and after ageing at temperatures up to 90°C. Rapid cooling produced cohesively failing bonds with shear strengths above 20 kg/em2. Weak, adhesively failing joints were produced under slow-cooling conditions. Strong bonds deteriorated when joints were aged at temperatures above 50°C, but further improvement in bond strength was observed upon ageing at lower temperatures. Experimental observations were consistent with the development of smectic structure in the polypropylene upon rapid cooling; a tendency for transcrystallization in slow-cooled joints was offset by the presence of weak boundary layers in the interface. Ageing produced further development of weak boundary layers and a transition from smectic to monoclinic crystallization in polypropylene. At higher ageing temperatures, the former effect seemed dominant; at lower temperatures, the structural change was assumed responsible for the observed improvement in bond strength.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760170707
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  • 8
    Digitale Medien
    Digitale Medien
    Dependence of mechanical properties in polyolefin blends on shear and thermal history (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 433-438 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Variously dispersed two-component blends of linear polyethylene and a thermoplastic rubber were subjected to different thermal histories after compression molding and their properties were evaluated. It has been shown that ultimate properties of the blends are not defined by the composition, but vary greatly with degree of dispersion and thermal history. Stronger materials failing in a ductile manner were produced under shock cool conditions and in, finely-dispersed blends. Brittle failures and weaker materials were favored by annealing procedures and in blends subjected to brief and/or lowshear dispersion procedures. Time and temperature dependent changes in properties of blends prepared under standard conditions have been observed and activation energies for the aging process calculated. Data interpretation was based on a hypothesis of domain morphology in the blends, and on the existence of “tie molecules” which help to determine the cohesive strength of domain boundaries.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760210710
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  • 9
    Digitale Medien
    Digitale Medien
    Crosslinking reactions in pigmented olefinic polymers (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 2049-2054 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Thermally initiated crosslinking reactions have been studied in a linear low-density polyethylene, and an ethylene - propylene rubber. The polymers contained conventional thermal stabilizers or one of three surface-coated rutile pigments. Enthalpies of crosslinking and reaction kinetics depended on the degree of terminal vinyl unsaturation in the polymers, that characteristic being greater in the rubber than in the polyethylene. The presence of thermal stabilizers did not exert any measurable influence on measured parameters of the crosslinking processes. The effects of rutile varied, depending on their surface acidity or basicity, as determined from chromatographic measurements. Basic rutile was found to reduce heats and to slow rates of reaction, while acidic rutiles did not affect the reactions. These observations may be attributed to interaction between the basic pigment surface and acidic moieties involved in the crosslinking reaction. © 1992 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1992.070461118
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  • 10
    Digitale Medien
    Digitale Medien
    Surface characteristics of polymer/small molecule blends (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 54 (1994), S. 743-752 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Inverse gas chromatographic data have been obtained for polystyrene, polycarbonate, and two substituted amines used as additives in the polymers. Surface energies have been determined and evaluations made of acid/base interaction parameters and Flory-Huggins χ values for the surface bounded interphase. It was shown that acid/base considerations are implicated in the miscibility of these polymer/additive systems. Surface energy analyses showed that surface and bulk compositions in blends differed whether or not the blend components were miscible. Composition differences were the result of thermodynamic drives to minimize surface free energy. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1994.070540605
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