Permeation Protocol
Standard test method for water vapor transmission rate through plastic films and sheeting. The astm f1249 utilizes a modulated infrared sensor to measure the mass of water molecules passing through a barrier material. Packaging engineers use this data to select materials that protect sensitive electronics from humidity.
Sensor Measurement
Detection of moisture occurs as the infrared beam identifies the concentration of water vapor in a nitrogen carrier gas. Inside the astm f1249 setup, the sample is clamped between a dry chamber and a wet chamber. The sensor records the change in infrared absorption over time.
This provides a precise reading of the barrier performance in grams per square meter per day.
Environmental Control
Temperature and humidity levels are strictly maintained during the procedure. The astm f1249 requires calibration at reference conditions to ensure that results are comparable across different laboratories. Any fluctuation in the thermal environment alters the kinetic energy of the water molecules.
This change can lead to an incorrect assessment of the shelf life of the package.
Performance Limit
Material thickness and polymer density influence the transmission rate. The astm f1249 defines the procedure for reporting the transmission rate and the permeance of the barrier. Verification involves testing standard reference films with known properties.
Accurate measurement prevents the premature failure of moisture sensitive components.
