Free volume dilatation in polymers by ortho-positronium.

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskrift

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.

Detaljer

Författare
  • Petra Winberg
  • Morten Eldrup
  • Frans Maurer
Enheter & grupper
Forskningsområden

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Kemi
Originalspråkengelska
Artikelnummer244902
TidskriftJournal of Chemical Physics
Volym136
Utgivningsnummer24
StatusPublished - 2012
PublikationskategoriForskning
Peer review utfördJa