Rapid pressure-decay technique for determining the O-2 and CO2 permeability coefficients of polymeric films considering the gas compressibility effect

This study describes a pressure-decay method for rapid assessment of the permeability of polymeric films. The equipment is a simplified version of that proposed by ISO 15105-1 2007 without the need of both vacuum and pressure operations. The gas compressibility effect was included in the calculations to represent the actual driving force for permeation. Darcy's law was fitted to pressure loss data to yield the permeability coefficients. The equipment is inexpensive, and the equations for calculating the gas permeability coefficient are more realistic than those proposed by the standard. Validation tests were performed with commercial films using O-2 and CO2. The polyethylene film had average permeability coefficients of P-O2 = 1.89 x 10(-17) m(3).m.m(-2).s(-1).Pa-1 and P-CO2 = 10.58 x 10(-17) m(3).m.m(-2).s(-1).Pa-1. The permeability for a commercial polyester film was P-O2 = 1.54 x 10(-19) m(3).m.m(-2).s(-1).Pa-1. Values closely matched those reported in the literature. Errors ranging from 43 to 79% were observed when the gas compressibility was ignored.

Automated summary

This study presents a simplified pressure-decay method for evaluating the permeability of polymeric films. The method eliminates the need for both vacuum and pressure operations and includes gas compressibility in the calculations. The equipment is inexpensive and provides more realistic equations for calculating the permeability coefficients compared to the standard method. Validation tests with commercial films showed close agreement with literature values, and significant errors were observed when gas compressibility was ignored.