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  • 1
    Electronic Resource
    Electronic Resource
    Single-chain polystyrene glasses (1993)
    s.l. : American Chemical Society
    Macromolecules 26 (1993), S. 2950-2953 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00063a046
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Stereocomplex formation in atactic poly(methyl methacrylate) I. Effect of solvents (2000)
    Springer
    Polymer bulletin 44 (2000), S. 533-538 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The stereocomplexation in three kinds of atactic poly (methyl methacrylate) (a-PMMA) films with different tacticities isolated from acetone, benzene, and chloroform solution was studied by Fourier transformation infrared (FTIR) and differential calorimetry scanning (DSC) techniques. Based on the results of infrared spectra, it could be deduced that stereocomplexes were formed in the films cast from acetone and benzene solutions with the increase in the population of trans-trans (tt) conformation of the backbone of i- and s-segments. It was assumed that the stereocomplexes formed by the interactions between i- and s-segments, possibly including intramolecular complexation. The stereocomplexation was also confirmed by the evidence of a endotherm with melt temperature over the range 180°C to 200°C, which was corresponded to the melting stereocomplex aggregates formed in the solutions and stabilized by the solvent molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002890070075
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Infrared spectroscopic studies of melting behavior of poly(ethylene 2, 6-naphthalenedicarboxylate) (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 60 (1996), S. 1385-1389 
    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 FTIR method was used to study the melting behavior of poly(ethylene 2, 6-naphthalene-dicarboxylate) (PEN) samples of different thermal history of crystallization. With subtraction of the spectra of PEN samples of different crystallinities and amorphous PEN, the spectra of crystalline trans conformers, amorphous trans conformers, and amorphous gauche conformers were obtained. By following the changes in intensity of various gauche and crystalline bands during heating, the phenomenon of multiple melting endothermic peaks was shown to be due to the melting of imperfect crystalline conformation formed during crystallization. For two-step annealed samples, the crystalline conformational defects change into a more perfect one during annealing at higher temperatures. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 4
    Electronic Resource
    Electronic Resource
    Subglass-transition-temperature annealing of poly(ethylene terephthalate) studied by FTIR (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 783-788 
    Details
    ISSN: 0887-6266
    Keywords: poly(ethylene terephthalate) ; sub-Tg ; annealing ; conformation ; infrared spectra ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Using FTIR spectroscopy we have examined conformational changes in the quenched and slowly cooled amorphous PET films during physical aging process. It was observed that the amount of trans conformers for quenched sample decreased upon sub-Tg annealing. For the slowly cooled sample that corresponds to a state closer to equilibrium, the amount of trans conformers hardly decreased, but increased gradually during sub-Tg annealing process. The conformational populations of these two samples tend to be identical with annealing time. These results demonstrate that sub-Tg annealing will lead to closer interchain packing and result in the formation of new cohesional entanglements along the chains. In situ FTIR studies on the conformational changes of these samples were also carried out during heating up of the sample through the glass transition region. The results showed that incremental changes of the amount of trans conformers in Samples Q and SC were gradual, while an abrupt change of trans conformers occurred in the sub-Tg annealed samples. These results were in agreement with the formation of the interchain cohesional entanglement due to sub-Tg annealing. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 783-788, 1998
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    The effects of physical ageing on conformational changes of poly(ethylene terephthalate) in the glass transition region (1996)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 197 (1996), S. 1485-1493 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In-situ FTIR studies on the conformational changes of poly(ethylene terephthalate) (PET) films with different thermal histories, i. e., quenched from the melt and sub-Tg annealed at different temperatures, were carried out while increasing the temperature through the glass transition region. The temperature dependencies of the infra-red spectra showed that incremental changes of the population of trans conformers in the quenched sample are gradual, while rather abrupt changes occur in the sub-Tg annealed samples. The magnitude and temperature of the abrupt changes of trans conformers were related with the temperature of sub-Tg annealing. An energy difference of 28.6 J/g between the trans and gauche conformational states was measured by the infra-red spectroscopic method. The energy absorbed during the abrupt conformational change represents only part of the energy of the endothermic peak observed by differential scanning calorimetry. The results are explained in terms of the formation of new cohesional entanglements during sub-Tg annealing.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1996.021970425
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  • 6
    Electronic Resource
    Electronic Resource
    Conformational changes of amorphous poly(ethylene terephthalate) films during uniaxial stretching (1991)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 301-307 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Rapid scanning Fourier transform infra-red spectroscopy was used to follow the changes in the population of trans conformers and in the infra-red dichroic functions of the bands characterizing the trans (T) and gauche (G) conformers and the chains in the amorphous regions during stretching of a solution-cast amorphous poly(ethylene terephthalate) (PET) film A in the glassy state (67°C) and in the rubbery state (88°C). Stretching at 67°C showed a yield stress peak followed by strain softening in the stress-strain curve. The population of trans conformers in the amorphous and crystalline regions, Ta + Tc, decreased in the pre-yielding region and then increased continuously after yielding. The T conformers formed during post-yield stretching showed high orientation, while the G conformers remained in low degree of orientation. Stretching at 88°C showed no pronounced yield stress peak in the stress-strain curve, and the population of T conformers did not change until the beginning strain-induced crystallization. A solvent-cast PET film annealed at 67°C for 24 h, the film N, showed a sharp and high yield stress peak in the stress-strain curve, and strain-induced crystallization occurred at lower draw ratio as compared to the film A. The film A showed a non-equilibrium high population of Ta conformers, part of which reverted to G conformers during sub-Tg annealing.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1991.021920212
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