The oxygen transmission rate (OTR) of the films was measured
according to ASTM standard method D 3985 using an OX-TRAN 2/
20 (Mocon, Inc., Minneapolis, MN, USA). Samples were exposed to
0% relative humidity (RH) and tested at 231 C. Oxygen permeability
(g mm/m2 day kPa)was calculated by multiplying the oxygen
transmission rate by the film thickness. The test was done in
triplicate and the mean value was reported