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  • 1
    Electronic Resource
    Electronic Resource
    On the triple melting behaviour of poly(ethylene succinate) (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 37 (1995), S. 249-254 
    Details
    ISSN: 0959-8103
    Keywords: poly(ethylene succinate) ; crystallization ; morphology ; electron microscopy ; thermal analysis ; 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 morphology of melt-crystallized poly(ethylene succinate) (PES) was investigated by optical microscopy and scanning electron microscopy, and the melting behaviour of PES was studied by differential scanning calorimetry (DSC). At low crystallization temperature imperfect crystals were formed which could melt and recrystallize during the DSC scan. Triple melting peaks were observed, and the melting behaviour was strongly dependent on crystallization time and scan rate. It was observed that crystallization at high temperature perfected the crystals (dominant and subsidiary lamellae in the spherulitic structure). Increasing the scan rate reduced the chance for reorganization. However, at high crystallization temperature two melting peaks were observed. The material formed was much more perfect, so that the melting process was not dominated by recrystallization. Accordingly, the cause of dual melting is the existence of two kinds of crystal perfection.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pi.1995.210370402
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  • 2
    Electronic Resource
    Electronic Resource
    Morphology and melting behaviour of poly(ethylene terephthalate) crystallized from the glassy state (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 38 (1995), S. 367-373 
    Details
    ISSN: 0959-8103
    Keywords: poly(ethylene terephthalate) ; annealing ; thermal behaviour ; morphology ; crystallization ; 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 influence of annealing conditions on the morphology and melting behaviour of poly(ethylene terephthalate) (PET) was studied. PET annealed under isothermal conditions often shows double melting endotherms depending on the annealing temperature (Ta) and the heating rate of the calorimeter. It was found that the morphological structure and the lower melting peak depend strongly on the annealing temperature, Ta. The increase of the lower melting peak temperature with Ta is due to an increase of the lamellar thickness within the spherulitic structure and to a higher crystallite perfection.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pi.1995.210380409
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  • 3
    Electronic Resource
    Electronic Resource
    Surface morphology and annealing of poly(butylene terephthalate) (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 38 (1995), S. 375-380 
    Details
    ISSN: 0959-8103
    Keywords: poly(butylene terephthalate) ; annealing ; thermal behaviour ; morphology ; 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 detailed description of the morphology and the complex melting behaviour of poly(butylene terephthalate) (PBT) annealed in the range 80-228°C is presented. Double melting endotherms can be obtained by annealing PBT in a differential scanning calorimeter (DSC). The lower endotherm corresponds to the melting of crystalline material formed at the annealing temperature in addition to some of the crystallized material reorganized during the quenching process. The upper melting endotherm results from the melting of a fraction of the original crystalline material reorganized during the DSC scan. Electron microscopy showed that the spherulitic structure over a wide range of annealing temperature below the melting point is unchanged. At high annealing temperatures, such as 228°C, electron micrographs showed that the narrow high melting peak is associated with the melting of isolated single crystals grown at that temperature.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pi.1995.210380410
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  • 4
    Electronic Resource
    Electronic Resource
    Morphology and melting behaviour of poly(vinylidene fluoride) crystallized from the melt (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 38 (1995), S. 381-385 
    Details
    ISSN: 0959-8103
    Keywords: poly(vinylidene fluoride) ; crystallization ; thermal behaviour ; morphology ; 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 influence of crystallization temperature on the melting behaviour and the morphology of poly(vinylidene fluoride) (PVF2) has been investigated. The DSC endotherms of PVF2 crystallized from the melt show at least two peaks. The peak areas depend on the thermal history of the samples and the heating scan rate. The area of the first peak was found to increase as the crystallization temperature or the scan rate increased. The double peak configuration was attributed to a melting-recrystallization process. Electron microscopy supports these results, for which only one type of lamella was found in the spherulitic structure.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pi.1995.210380411
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  • 5
    Electronic Resource
    Electronic Resource
    Morphology and melting behaviour of poly(butylene terephthalate) (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 37 (1995), S. 47-52 
    Details
    ISSN: 0959-8103
    Keywords: poly(butylene terephthalate) ; melting behaviour ; morphology ; 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 detailed description of the morphology and the complex melting behaviour of poly(butylene terephthalate) crystallized isothermally from the melt is presented. Triple, double, or single melting endotherms can deliberately be obtained by varying the heating rate in the differential scanning calorimeter (DSC). At low crystallization temperatures, Tc, triple melting endotherms were seen when the specimen was scanned at 10°C/min, while at high Tc a single endotherm was seen. In the case of the triple melting peaks, the first endotherm corresponds to melting of the imperfect crystals formed at the crystallization temperature. The second endotherm originates from melting of the perfect crystals in the initial distribution, and to some recrystallized meterial. The third endotherm is due to melting of the original crystalline material reorganized during the DSC scan. A detailed morphological study of the isothermally crystallized samples by electron microscopy showed that dominant and subsidiary lamellae in the spherulitic structure are related to perfect and imperfect crystals, respectively.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pi.1995.210370106
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  • 6
    Electronic Resource
    Electronic Resource
    Reactivity of 4-acetyl-3-chloro-5,6-diphenylpyridazine towards some nucleophilic reagents, Synthesis of Some Fused Pyridazine Derivatives (1989)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 399-404 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 4-Acetyl-3-chloro-5,6-diphenylpyridazine (1), prepared by the action of phosphorus oxychloride on 4-acetyl-5,6-diphenylpyridazin-3(2H)-one (2), reacts with hydrazine hydrate and phenylhydrazine to give the pyrazolinopyridazine derivatives (3a, b) respectively. Reaction of 1 with hydroxylamine hydrochloride gave the isoxazolopyridazine derivative (5), while its reaction with sodium azide in dimethyl formamide gave the tetrazolopyridazine derivative (8). Primary amines react with 1 to give either 9 or 10 depending upon the reaction conditions. Treatment of 1 with piperidine or morpholine gave the products 11a, b, respectivly. 4-Acetyl-5,6-diphenylpyridazin-3(2H)-thione (13) was readily obtained by the action of thiourea on ethanolic solution of 1. The reactions of 1 with phenols were also investigated.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19893310308
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  • 7
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    Space processing of chalcogenide glasses (1975)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Chalcogenide glasses are discussed as good infrared transmitters, possessing the strength, corrosion resistance, and scale-up potential necessary for large 10.6-micron windows. The disadvantage of earth-produced chalcogenide glasses is shown to be an infrared absorption coefficient which is unacceptably high relative to alkali halides. This coefficient is traced to optical nonhomogeneities resulting from environmental and container contamination. Space processing is considered as a means of improving the infrared transmission quality of chalcogenides and of eliminating the following problems: optical inhomogeneities caused by thermal currents and density fluctuation in the l-g earth environment; contamination from the earth-melting crucible by oxygen and other elements deleterious to infrared transmission; and, heterogeneous nucleation at the earth-melting crucible-glass interface.
    Keywords: ASTRONAUTICS (GENERAL)
    Type: NASA-CR-120745 , AR-1
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Space processing of chalcogenide glass (1976)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The manner in which the weightless, containerless nature of in-space processing can be successfully utilized to improve the quality of infrared transmitting chalcogenide glasses was investigated. The following conclusions were reached: (1) Laboratory experiments have established the techniques, processes and equipment necessary for the production of high purity chalcogenide glasses. (2) Processing techniques have been successfully adopted for Ge28Sb12Se60 glass in a 1-g environment. (3) The Ge28Sb12Se60 glasses that have been processed have optical transmission around 63% (5 mm thick). (4) Laboratory experiments have established that the use of precursor materials in powdered form increases the oxygen contamination of the processed glass. This indicates that high purity precursor materials in bar or pellet form should be used. (5) Modifications were made on the MSFC acoustic levitator in an attempt to improve levitation stability during long-time experiments. Room temperature experiments on As2S3 glasses and high temperature experiments on polystyrene were conducted.
    Keywords: ASTRONAUTICS (GENERAL)
    Type: NASA-CR-144278 , ASR-2
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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