Relation between the activation energy of oxygen diffusion and the instantaneous shear modulus in propylene carbonate near the glass transition temperature

Abstract

We discuss the transport of small gas molecules in organic glassy matrices using oxygen diffusion in propylene carbonate as an example. The jumps of a penetrant from one interstitial cavity to another require energy to expand the channel between cavities to the size of the penetrant. It has been established that at temperatures below and slightly above the glass transition temperature, the activation energy of oxygen diffusion, E, is related to the instantaneous shear modulus G∞ of propylene carbonate via the equation E = V × G∞, where V is the temperature-independent parameter that characterizes the volume of the channel. Consequently, the E value is the work necessary for elastic deformation of the surrounding matrix to expand the channel available for oxygen diffusion.

Sorption of light gases in glassy poly(ethyl methacrylate)

“…The activation energy of diffusion can be interpreted as the energy which is needed to form the channel between the sorption sites . Its value depends on the distance between the sorption sites, and whereby on their concentration.…”

“…According to molecular dynamics simulations, only the elastic motions of matrix molecules cause the opening of channels . The activation energy of diffusion can be estimated as the strain energy of the dilatation of a cylindrical channel from a diameter d 0 to d in an elastic continuum . Its value is given by the equation: where λ is the distance between the sorption sites and is the instantaneous shear modulus of medium.…”

“…The activation energy of diffusion can be interpreted as the energy which is needed to form the channel between the sorption sites. [55][56][57][58] Its value depends on the distance between the sorption sites, and whereby on their concentration. According to computer modeling of the molecular structure of polymers, 1,51 the characteristic length of the diffusion jump of small molecules, such as molecules of nitrogen or methane, lies in the range from 5 to 6 Å.…”

“…3,59 The activation energy of diffusion can be estimated as the strain energy of the dilatation of a cylindrical channel from a diameter d 0 to d in an elastic continuum. 58 Its value is given by the equation 60 :…”

Influence of the Inclusion of Propylene Carbonate Electrolyte Solvent on the Microstructure and Thermal and Mechanical Stability of Poly(l-lactic acid) and Poly(vinylidene fluoride-co-hexafluoropropylene) Battery Separator Membranes

“…The liquid cooling shows a melting temperature at −48.8 °C, and a glass-transition temperature, T g , at about −115 °C. 22 − 24 …”