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@ARTICLE{Harms:14187,
      author       = {Harms, S. and Rätzke, K. and Faupel, F. and Schneider,
                      G.J. and Willner, L. and Richter, D.},
      title        = {{F}ree {V}olume of {I}nterphases in {M}odel
                      {N}anovomposites {S}tudied by {P}ositron {A}nnihilation
                      {L}ifetime {S}pectroscopy},
      journal      = {Macromolecules},
      volume       = {43},
      issn         = {0024-9297},
      address      = {Washington, DC},
      publisher    = {Soc.},
      reportid     = {PreJuSER-14187},
      pages        = {10505 - 10511},
      year         = {2010},
      note         = {Financial support by German research society (SPP 1369
                      Interfaces and Interphases Project Ra 796/5 1) is
                      acknowledged Scientific discussion and hints to literature
                      by Prof G Dlubek (Halle) are deeply acknowledged Help with
                      DSC measurements and manuscript preparation by Isabel Jonas
                      is gratefully appreciated The authors thank Dr M Q Shaikh
                      for careful reading of the manuscript},
      abstract     = {The free volume studies were performed in well
                      characterized model nanocomposites by positron annihilation
                      lifetime spectroscopy (PALS) to explore the influence of the
                      interphase nanoscale character of the hydrophobically
                      functionalized filler particles and the nanoscale particle
                      size on positron parameters A weakly repulsive system, which
                      should not form an interphase, was obtained by mixing of low
                      molecular weight poly(ethylene-alt-propylene) (PEP) and
                      hydrophobically modified silica with varying concentration A
                      low molecular weight sample was chosen Because of a finite
                      centre of mass diffusion and a low radius of gyration the
                      interstitials between particles are effectively filled and
                      hence a most suitable model system is obtained The absence
                      of an interphase was confirmed by neutron scattering and
                      neutron spin echo measurements DSC experiments showed a
                      constant glass transition temperature T-g and a decrease in
                      Delta c(p) at T-g with increasing filler concentration as
                      expected In contrast, PALS measurements showed decreasing
                      glass transition temperatures and a strong drop of the
                      thermal expansion coefficient above T-g These seemingly
                      conflicting results are demonstrated to be due to nanoscale
                      character of the hydrophobically functionalized filler
                      particles with sizes in the range of the positronium
                      diffusion length which requires taking into account
                      out-diffusion of positronium from the particles In
                      particular, it is shown that the changes on PALS parameters
                      such as o-Ps lifetime or its intensity, with increasing
                      filler content cannot be attributed to the formation of an
                      interphase with properties different from the polymer matrix
                      Like the neutron scattering experiments, PALS does not find
                      any evidence of an interphase between the filler and the
                      polymer within the resolution limit of the present
                      technique, which is in agreement to the neutron scattering
                      experiments},
      keywords     = {J (WoSType)},
      cin          = {IFF-4 / IFF-5 / Jülich Centre for Neutron Science JCNS
                      (JCNS) ; JCNS},
      ddc          = {540},
      cid          = {I:(DE-Juel1)VDB784 / I:(DE-Juel1)VDB785 /
                      I:(DE-Juel1)JCNS-20121112},
      pnm          = {BioSoft: Makromolekulare Systeme und biologische
                      Informationsverarbeitung / Großgeräte für die Forschung
                      mit Photonen, Neutronen und Ionen (PNI)},
      pid          = {G:(DE-Juel1)FUEK505 / G:(DE-Juel1)FUEK415},
      shelfmark    = {Polymer Science},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000285429400048},
      doi          = {10.1021/ma1022692},
      url          = {https://juser.fz-juelich.de/record/14187},
}