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  • 1
    Electronic Resource
    Electronic Resource
    Radiometric investigations on thermal expansion and transitions in polymers (1967)
    Springer
    Rheologica acta 6 (1967), S. 390-396 
    Details
    ISSN: 1435-1528
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Zusammenfassung Die vorliegende Arbeit beschreibt eine verbesserte radiometrische Methode zur Messung der WÄrmeausdehnung fester Stoffe, insbesondere von Hochpolymeren. Die Änderungen der Probendimensionen werden als entsprechende Änderungen der Transmission derΒ-Strahlen registriert. In erster Linie wird beabsichtigt, damit thermische Umwandlungen hochpolymerer Stoffe zu verfolgen. An einer Reihe von Meßresultaten wird gezeigt, daß die Methode für diesen Zweck wohl geeignet und mit normaler Dilatometrie vergleichbar ist. Die wiedergegebenen Beispiele beziehen sich auf die Glasumwandlung amorpher Hochpolymere, die Umwandlungen bei Zimmertemperatur in PTFE — wo auch der Hystereseffekt aufgelöst worden ist -, Unterschiede in der WÄrmeausdehnung von PE verschiedener KristallinitÄt usw. In sÄmtlichen FÄllen konnte eine gute übereinstimmung mit den entsprechenden Literaturangaben erzielt werden.
    Notes: Summary The present paper describes an improved radiometric method for the measurement of thermal expansion of solids, especially high polymers. The changes in the dimensions of the sample are recorded as the corresponding changes in the transmission ofΒ-rays. In the first place, the method is aimed at following thermal transitions in high polymers. A number of experimental examples shown in the paper demonstrate that the method is well suited for this purpose and that it gives results comparable with ordinary dilatometry. These examples relate to the glass transition in amorphous polymers, the room temperature transitions in PTFE including the accompanying hysteresis effect, differences in thermal expansion of PE of varying crystallinity, etc. A good agreement with the corresponding literature data was achieved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01984636
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  • 2
    Electronic Resource
    Electronic Resource
    The imbedded disk retraction method for measurement of interfacial tension between polymer melts (1996)
    Springer
    Rheologica acta 35 (1996), S. 458-469 
    Details
    ISSN: 1435-1528
    Keywords: Interfacial tension ; high viscosity ; high molecular weight ; large viscosity ratios ; poly(methyl methacrylate) ; polystyrene ; imbedded disk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract A method for measuring interfacial tension of high viscosity polymer melts at elevated temperatures is described. The method involves the tracking of the shape evolution of a disk of one material imbedded in a second one. This makes it possible to determine the interfacial tension over a relatively short time period. The technique of preparing the samples makes it possible to measure on practically any combination of polymer melts without restrictions on viscosities and melting temperature, as long as one of the materials is transparent in the molten state. The retraction of the disk is observed by using a microscope with a high resolution video camera. The camera is connected to a video frame grabber in a personal computer which is programmed to collect images with preselected time intervals. Data of the retraction is acquired by using an image analysis software, measuring the average radius of the disk. The driving force for the shape evolution is interfacial tension and it is balanced by viscous forces. The analysis of the retraction process is done analytically with a simplified one-dimensional model. The model has been compared to experiments with the system PS/PMMA at 210 °C, covering viscosity ratios over a range of six decades and five different molecular weight values of PS. It is shown that interfacial tension can be determined over the whole range and a value of 1.1±0.2 mN/m was obtained for all samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00368996
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  • 3
    Electronic Resource
    Electronic Resource
    Anomalous behavior of electrical conductivity and thermal noise in carbon black-containing polymers at Tg and Tm (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 19 (1975), S. 831-845 
    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: Pronounced maxima in resistivity-temperature curves have been found at or above Tg for a number of amorphous polymers (PS, PMMA, PVC) containing a small percentage of carbon black. The maxima appeared only after a certain period of storage at T 〈 Tg or at heating rates substantially higher than those used in cooling the samples prior to the measurement. For this reason, no maxima were observed during cooling. In crystalline polymers (PE, PP), maxima at Tm appeared both on heating and cooling. Marked relaxation effects (time-dependent resistivity) were recorded in the Tg and Tm regions. Good agreement was found between resistivity and thermal noise data.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1975.070190319
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  • 4
    Electronic Resource
    Electronic Resource
    Thermal and current noise in carbon black-filled polystyrene and polyethylene in the vicinity of Tg and Tm (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 489-499 
    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: Thermal and current noise in carbon black-filled polystyrene and polyethylene was studied in the vicinity of Tg and Tm. A highly conductive grade of carbon black was used (Ketjenblack EC): 4% for PS and 6.5% for PE. Pronounced maxima in noise voltage were found at Tg for PS and Tm for PE. Prolonged storage at T lower than Tg enhanced the intensity of the noise peak at Tg for PS. A hysteresis occurred on cooling after a heating cycle, with the current and thermal noise being lower on the cooling cycle (no maximum in the case of PS). The peak temperature was lower for PE on the cooling cycle. Good agreement was found between experimental and calculated thermal noise values. The thermal noise spectra were white within the temperature range of 20° to 140°C. The appearance of the current noise peaks could be associated with a conduction model where a decrease in the number of contact points in the carbon black network occurs in the transition regions. This is in accordance with the concept proposed earlier that the carbon black network existing in a polymer undergoes a rearrangement when the polymer melts (softens) or solidifies.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1976.070200221
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  • 5
    Electronic Resource
    Electronic Resource
    Electrical noise characteristics of carbon black-filled linear low density polyethylene near the percolation threshold (1993)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 33 (1993), S. 573-580 
    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: Electrical noise measurements have been used to study electrical conduction in carbon black-filled linear low density polyethylene. Measurements of the resistivity, real part of the relative permittivity, thermal noise, and current noise have been carried out for carbon black contents and temperatures below, near, and above the percolation threshold for electrical conduction. The current noise shows a 1 /fα frequency dependence, with α near unity close to the percolation threshold, but increasing to 1.5 at higher resistivities or temperatures.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760330910
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  • 6
    Electronic Resource
    Electronic Resource
    Electrical transport in 0-3 epoxy resin-barium titanate-carbon black polymer composites (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1847-1856 
    Details
    ISSN: 0887-6266
    Keywords: electrical transport ; dielectric properties ; barium titanate ; carbon black ; epoxy resin ; relaxation processes ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Conductivity and dielectric constant of a three-component 0-3 composite of epoxy resin-barium titanate-carbon black (0-3 composites are systems in which the filler is in the form of 0-dimensional (point-like, disperse) particles in a three-dimensional polymeric matrix1) have been investigated both at DC and the frequency range of 20-106 c/s. The effect of barium titanate concentration on percolation threshold, critical indices and the mechanism of conduction has been examined. An attempt was made to describe the electrical properties of composites with models originally developed for two-component systems' dielectric-conductor. With increasing barium titanate concentration the agreement of experimentally found frequency dependencies of conductivity and dielectric constant with models based on Debye's equation was found to degrade. An adequate description of electrical properties of composites' dielectric-ferroelectric-conductor should be based on the Havriliak-Negami equation. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1847-1856, 1998
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 7
    Electronic Resource
    Electronic Resource
    Mechanically induced maxima in the thermal noise spectrum of carbon-black-filled polyethylene during melting (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 1157-1160 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1976.180140617
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