Diffusion of CO2

Thread by Calvin on 23 Jul 2016 at 01:43:41 
Hi, I was wondering what the diffusion rate of CO2 through PET is like when compared to other polymers such as PLA and HDPE.
Thanks,
Calvin

    Comment by Composite Agency on 23 Jul 2016 at 09:55:23  | |responses: 0|
    We can compare CO2 diffusion of HDPE and PET using CheFEM prologue permeation - mechanical response simulation software. Assuming a temperature of 23 degr C and both materials having a crystallinity of say 60 percent, the results are (D= diffusion coefficient, S = solubility in stp units):

    CO2->HDPE: D = 8E-12 m2/s, S = 0.4 cc stp / cc bar
    CO2->PET: D = 2E-13 m2/s, S = 0.6 cc stp / cc bar

    Permeation of CO2 in PET (P=D x S) is much slower due to the much slower diffusion coefficient.

    Kind regards,
    Sijmon van der Wal
    Composite Agency