Mathematical models of diffusion-controlled oxidation

A number of mathematical models to describe diffusion-controlled oxidation 

The rate of oxygen absorption is diffusion-controlled from the film surface in thin films however, the rate is linearly proportional to the film thickness [259, 280]. 

The diffusion effects inherent in a polymer film are generally expressed by a differential equation according to Pick s laws of diffusion. The solution to this equation is determined by applying suitable initial and final boundary conditions [259, 280, 494, 643, 1087, 2274]. 

Oxygen diffusing into a solid polymer film through both surfaces is being consumed by a first-order or pseudo-first-order chemical reaction [571, 643, 1591]. 

For a given polymer sample, it is possible to define at least two distinct kinetic regimes of oxidative degradation separated by a pseudo-hyperbolic boundary in the [r F] graph (Fig. 2.7), where  

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