Transport processes in polymer membranes. Part 4

Abstract

This paper is the fourth in a series of scientific papers on the transport of solvent molecules in polymer membranes. The objectives on realizing the basic properties of the polymer membrane - “semi-permeability” - determining thermodynamic and kinetic parameters of the system solvent-polymer membrane during the passage of small solvent molecules through the membrane body are clearly stated in the paper. It is shown that the thermodynamic conditions, required for dissolving any solvent in the given membrane can be determined and predicted. Things stand worse with describing the kinetic processes of solvent molecules motion in the macromolecular structure of the polymer membrane. The basic problem, which is that the thermodynamic system solvent-membrane and all the processes, occurring in the system, are not perfect and so they cannot be described by classical laws such as Henry’s or Fick’s laws, is defined. In this paper, the authors have made an attempt to determine the main kinetic parameters using the results of sorption and desorption of various solvents in the membranes, differing by the macromolecular lattice stiffness. These results correlate well with the structural feature of membranes, as well as properties of solvents. The method of representing bulk diffusion processes as a combination of several individual diffusion parts of the membrane, which are suitable for applying classical diffusion laws and determining their numerical values, is noteworthy.