Permeance (P): The ratio of the gastransmissionrate to the difference in partial pressure of the gas on the two sides of the film.
译文：气体透过系数（P）：单位时间内单位压力差下稳定透过单位面积上单位厚度的试样的气体体积。
2
Oxygen gastransmissionrate ( O2 GTR ) is determined after the package has been mounted on a test fixture and has equilibrated in the test environment.
氧气透过率（O2 GTR）是将包装物固定在测试装置上并在测试环境中达到平衡后测定的。
3
GasTransmissionRate (GTR) : the quantity of a given gas passing through a unit of the parallel surfaces of a plastic film in unit time under the conditions of test.