Gas transport parameters, density and free volume of nanocrystalline poly-2,6-dimethylphenylene oxide.

Abstract Poly(2,6-dimethylphenylene oxide-1,4) (PPO) belongs to a fairly investigated group of polymers that, nevertheless, provokes permanent research interest. The current study is focused on a combination of various physicochemical methods of polymer testing (DSC; molecular weight distribution; surface area by low-temperature adsorption isotherms of nitrogen and carbon dioxide; X-Ray diffraction analysis; hydrostatic measurement of density; gas permeability and diffusion measurement) with variation of molecular weight and different states of polymer samples (amorphous, semi-crystalline, biaxial-oriented). The alteration of the density, gas permeability and diffusion parameters is evaluated through modeling of PPO as a polymer-polymer blend material with amorphous, nano-sized crystalline (≤ 7 nm), and so-called rigid amorphous fraction (RAF) phases. The estimation of the phase properties of PPO samples allows to conclude that the permeability and diffusion characteristics decline in a row crystalline > amorphous > RAF.