Diffusion Coefficients

The chief difficulty with any diffusion scenario is finding the diffusion coefficient, D. One approach is to follow a method approved by US and European regulatory bodies which provides a set of standard polymers and estimates D from the MWt of the molecule and the temperature, T (°K), for the specific scenario. The formula is:

D=104exp(A-C1MWt0.666+C2MWt-C3/T) cm²/s

C1=0.135, C2=0.003, C3=10454. A in turn depends on T and two polymer specific terms, A* and τ:


When you choose a polymer the A* and τ values are shown and from your given MWt and T, D is calculated

Diffusion Coefficients

T °C
D cm²/s

Although this formula is often used in food packaging applications, be aware that this app carries no guarantees that the calculated D values are correct. For example, the linear, branched and cyclic versions of a molecule with the same molecular weight will each have different D values; branched and cyclic molecules have lower D values than linear ones.

The official site of Hansen Solubility Parameters and HSPiP software.