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Free volume dilatation in polymers by ortho-positronium.

In English

Författare

  • Petra Winberg
  • Morten Eldrup
  • Frans Maurer

Summary, in English

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.

Publiceringsår

2012

Språk

Engelska

Publikation/Tidskrift/Serie

Journal of Chemical Physics

Volym

136

Issue

24

Dokumenttyp

Artikel i tidskrift

Förlag

American Institute of Physics (AIP)

Ämne

  • Chemical Sciences

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0021-9606