Permeation, Sorption, and Diffusion in Poly lactic acid

PERMEATION, SORPTION, AND DIFFUSION IN POLY(LACTIC ACID) 

Permeation processes take place through a membrane that separates two fluid phases (gas, vapor, or liquid) containing low molecular weight species with differing chemical potential. The molecules at the side of the higher chemical potential tend to diffuse through the membrane and equilibrate the chemical potential on both sides. The permeation process in continuous polymeric materials is accomplished 

Permeation mechanisms have been extensively studied by many researchers [3-5]. Adolf Pick, in 1855, derived the general equations of the diffusion process, and in 1975 a detailed mathematical analysis was compiled by John Crank [6]. The diffusion process for the steady state is described by the general Pick s first law (Equation 12.1, where the left-hand side of the equation is the flux (F), and the right-hand side is the product of the diffusion coefficient (D) and the gradient operator of the chemical potential (m)). 

Poly(lactic add) Synthesis, Structures, Properties, Processing, and Applications, edited by R. Auras, L.-T. Lim, S. E. M. Setke, and H. Tsuji Copyright 2010 John Wiley Sons, Inc. 

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