A method of increasing the gas transmission rate of a packaging film comprises providing a packaging film that comprises at least about 0.001 weight % of single-walled carbon nanotube material based on the weight of the film. The packaging film is exposed to an amount of radiation energy effective to increase the oxygen transmission rate of the packaging film by at least about 100 cc (STP)/m2. day (1 atm, 0% RH, 23.degree. C.).