Estimation of styrene diffusion coefficient in PS

Where no experimental diffusion coefficient data in the polymer is available an estimation for the upper limit diffusion coefficient Dp can be made using the empirical correlation given in Eq. (15-1) (Chapter 15)  

AP accounts for the effect of the polymer on diffusivity, GPPS = -4, HIPS = -3 Mr is the substance s molecular weight T is the temperature in Kelvin (K= C + 273) 

Material (monomer content) Temperature (°C) Diffusion Coefficient (cm2/s) Activation Energy (J/mol) Reference 

GPPS = general purpose polystyrene HIPS = high impact polystyrene a) 1 1 HIPS GPPS diffusion coefficient equation In D = 15.61 - 14 500- b) apparent diffusion coefficient calculated from experimental migration data. (1 /T(K)) 

Example 14-3 Continuing with the preceding examples for the migration of styrene from polystyrene, this time assume the migration is diffnsion controlled. Assume the product has a 6 month shelf life at room temperature (23 °C). 

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