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Free volume dilatation in polymers by ortho-positronium.

Winberg, Petra LU ; Eldrup, Morten LU and Maurer, Frans LU (2012) In Journal of Chemical Physics 136(24).
Abstract
The possibility of positronium induced free volume cavity expansion in some polymers above the glass transition temperature was investigated using experimental positron annihilation lifetime data from the literature for polydimethylsiloxane, polyisobutylene, and polybutadiene as function of temperature. The results suggest that free volume sites can expand towards an equilibrium size, determined as the equilibrium Ps-bubble size defined earlier for low-molecular-weight liquids. The expansion can be explained by the increase of molecular mobility and hence decrease of relaxation times, which at the higher temperatures approach the o-Ps lifetimes. Nanoscale viscosities were estimated using Navier-Stokes equation and were found to be several... (More)
The possibility of positronium induced free volume cavity expansion in some polymers above the glass transition temperature was investigated using experimental positron annihilation lifetime data from the literature for polydimethylsiloxane, polyisobutylene, and polybutadiene as function of temperature. The results suggest that free volume sites can expand towards an equilibrium size, determined as the equilibrium Ps-bubble size defined earlier for low-molecular-weight liquids. The expansion can be explained by the increase of molecular mobility and hence decrease of relaxation times, which at the higher temperatures approach the o-Ps lifetimes. Nanoscale viscosities were estimated using Navier-Stokes equation and were found to be several orders of magnitude lower than the macroscopic viscosity at the same temperature. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Chemical Physics
volume
136
issue
24
publisher
American Institute of Physics
external identifiers
  • wos:000305881100042
  • pmid:22755598
  • scopus:84863508975
ISSN
0021-9606
DOI
10.1063/1.4729561
language
English
LU publication?
yes
id
19fe243d-c949-49a6-84cc-2610629033a0 (old id 2967561)
date added to LUP
2012-09-10 12:37:21
date last changed
2017-08-20 03:01:21
@article{19fe243d-c949-49a6-84cc-2610629033a0,
  abstract     = {The possibility of positronium induced free volume cavity expansion in some polymers above the glass transition temperature was investigated using experimental positron annihilation lifetime data from the literature for polydimethylsiloxane, polyisobutylene, and polybutadiene as function of temperature. The results suggest that free volume sites can expand towards an equilibrium size, determined as the equilibrium Ps-bubble size defined earlier for low-molecular-weight liquids. The expansion can be explained by the increase of molecular mobility and hence decrease of relaxation times, which at the higher temperatures approach the o-Ps lifetimes. Nanoscale viscosities were estimated using Navier-Stokes equation and were found to be several orders of magnitude lower than the macroscopic viscosity at the same temperature.},
  articleno    = {244902},
  author       = {Winberg, Petra and Eldrup, Morten and Maurer, Frans},
  issn         = {0021-9606},
  language     = {eng},
  number       = {24},
  publisher    = {American Institute of Physics},
  series       = {Journal of Chemical Physics},
  title        = {Free volume dilatation in polymers by ortho-positronium.},
  url          = {http://dx.doi.org/10.1063/1.4729561},
  volume       = {136},
  year         = {2012},
}