Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Relaxation dynamics of H-bonded liquids confined in porous silica gels by Rayleigh wing spectroscopy (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 2292-2299 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Reorientational dynamics of neat liquid propylene glycol molecules is compared with that of confined molecules in 25 and 75 Å pores of a sol-gel porous glass by means of depolarized light-scattering spectroscopy. The experimental spectra, performed as a function of temperature, show unambiguously the slowing down of the collective reorientational processes triggered by the confinement effects. Such results confirm the main role played by the strong dipolar interactions on the dynamics of hydrogen-bonded liquids diffusing within nanoscopic spherical pores. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.474605
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Low-temperature excess specific heat and fragility in polymers: Crystallinity dependence (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 7625-7631 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A study of the mechanical characteristics and the low-temperature specific heat has been performed on a class of polymers whose crystallinity degree varies in a wide range, from a wholly amorphous to a highly crystalline structure. Typical features of the amorphous phase have been analyzed in order to shed further light on their correlations: the deviation from the exponentiality and the "fragility" obtained by modeling the mechanical αa-relaxation and the excess specific heat over the predictions of the Debye theory. It has been found that increasing crystallinity enhances the nonexponentiality of the αa-relaxation, and decreases both the fragility and the excess specific heat. This behavior is intrinsic to semicrystalline polymers. Consequently, the recently suggested correlation between the degree of fragility and the additional low-energy vibrations causing the low-temperature excess specific heat in glasses fails in semicrystalline polymers. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.477384
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Microscopic origin of anelastic relaxations in polyethylene oxide-sodium thiocyanate complexes (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 1122-1126 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The temperature behavior (100–400 K) of the mechanical characteristics (internal friction and resonant frequency) of polyethyleneoxide-NaSCN polymeric electrolytes reveals the presence of anelastic relaxations, which arise from local and cooperative microscopic motions. The low-temperature γ relaxation is explained in terms of a relaxation time distribution, which is interpreted as arising from random deviations in the local arrangement of the relaxing particles. Moreover, the elastic and anelastic features, as a function of the salt content, give some insight concerning their microscopic origin and the connection between the structure and the fast ion dynamics in this kind of systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343451
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Size effect of the alkali cation on the structure and the molecular mobility of solid polymeric electrolytes (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 5834-5840 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Polymeric electrolytes of the poly(ethylene) oxide (PEO) potassium thiocyanate system have been studied by analyzing the temperature dependence of the low-frequency (0.3–30 Hz) mechanical characteristics. It is found that the local and cooperative molecular motions characterizing the host polymer are strongly influenced by the addition of the salt, as a result of strong interactions between the polymeric chains and the alkaline salt molecules, which ensure the formation of homogeneous complexes. In the low-concentration region (molar fraction X≤0.08) a relevant enhancement of the noncrystallinity and a considerable shift of the glass-to-rubber transition toward higher temperatures characterize the blends. Further salt addition stiffens the material, this peculiarity being connected to the gradual formation of a crystalline complex with a fixed stoichiometry. It is believed that the observed inversion in the structural trend arises from an increase of the interchain interactions via the polarizing effects of the salt molecules. At low temperatures the single γ relaxation, observed in pure PEO and in complexes of the same kind with smaller cations, is modified by the presence of the salt; two close peaks appear, whose strength follows behavior closely correlated to that of the primary relaxation. A quantitative interpretation in terms of a parallel relaxation permits the microscopic origin to be discussed and the underlying local motions to be ascribed to the amorphous fraction of the polymer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350478
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Anelastic relaxations and molecular motions in polymeric electrolytes (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 704-709 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A study of the frequency (0.1–30 Hz) and temperature (120–373 K) behavior of the internal friction and of the dynamic modulus was carried out in polyethylene oxide (PEO)-Ba(SCN)2 polymeric electrolytes. The mechanical spectra reveal the presence of the following anelastic relaxations: (a) the γ process due to localized movements within the main chain, (b) a process due to relaxing particles introduced by salt, and (c) the αa process associated to the glass-rubber like transition. Both the γ- and αa -loss peaks are shifted to higher temperatures by the addition of salt. A careful analysis of the observed peculiarities permits us to gain an insight on the microscopic nature of the relaxation mechanisms and to associate the γ relaxation with localized segmental motion within the amorphous phase. In pure PEO and in the complex with the lowest salt content, the loss due to the melting transition of PEO crystals is also observed. The cited loss is lacking in the complexes with a salt molar fraction X〉0.05, which show an enormous enhancement of the strength of the αa relaxation. It is argued that the addition of a salt with a divalent cation to semicrystalline PEO gives rise to completely amorphous single phase structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347353
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Locally heterogeneous dynamics in miscible blends of poly(methyl methacrylate) and poly(vinylidene fluoride) (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 7316-7322 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Comparative measurements of specific heat capacities (temperature interval between 2 and 500 K), and of low frequency mechanical spectroscopy (temperature interval between 120 and 400 K) in poly(methyl methacrylate) (PMMA) and poly(vinylidene fluoride) (PVDF) amorphous blends show the existence of single calorimetric and mechanical glass transition temperatures, as a clear indication of the existence of homogeneous single-state structures. Below Tg, the experimental data reveal distinct local relaxation processes within the backbone of the individual components, while the heat capacities below 15 K can be explained in terms of a two-phase model (i.e., a simple linear overlap of the contributions from wholly amorphous PMMA and PVDF, weighted by their proportions). These findings are associated with locally heterogeneous relaxation and vibrational motions, and are regarded as experimental evidence for the existence of a nanoscopic length scale where the dynamics of a blend exhibits a heterogeneous regime. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1464821
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Anelastic relaxations in AgI - doped borophosphate glasses
    Amsterdam : Elsevier
    Solid State Ionics 18-19 (1986), S. 449-453 
    Details
    ISSN: 0167-2738
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0167-2738(86)90158-X
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Sound velocity behavior in silver borate glasses
    Amsterdam : Elsevier
    Solid State Ionics 18-19 (1986), S. 415-420 
    Details
    ISSN: 0167-2738
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0167-2738(86)90152-9
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Size effects of Ag^+ ion in the computer simulation of Ag"2O-B"2O"3 glasses
    Amsterdam : Elsevier
    Solid State Ionics 28-30 (1988), S. 148-151 
    Details
    ISSN: 0167-2738
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0167-2738(88)80023-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Raman scattering in a-Se bulk near T"g
    Amsterdam : Elsevier
    Solid State Communications 33 (1980), S. 1139-1141 
    Details
    ISSN: 0038-1098
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0038-1098(80)91092-3
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...