Evaluation, modification and adaptation of an airflow test method for polyurethane foams

Abstract

The need for a reliable method for measurement of the permeability through fabrics was satisfied by the development of ASTM D 737 method, using a differential-pressure air permeability tester (such as Frazier™ airflow tester). In this method, the permeability of a sample is measured at a controlled differential pressure across the sample. This method, otherwise used predominantly for textile fabrics, is currently being used to measure airflow through polyurethane foams. This method possesses a distinct advantage over other airflow methods owing to the non-dependence of airflow data on ambient pressure, which makes the obtained airflow data accurate. However, there are certain difficulties associated with this testing method pertaining to the leakage of air around the sample. In this project, the data from the commercially available Frazier™ airflow tester are evaluated for dependence on sample variables, such as clamping pressure and sample thickness pertaining to foams. In order to improve the sealing around the edges of foam samples, an accessory was attached to the existing Frazier™ airflow tester, which can quantify the amount of pressure that is applied on the foam sample during the test. This has not only facilitated acquisition of airflow data at different values of applied pressure on the sample, but also considerably improved the seal around the sample. The airflow data obtained by the ASTM D 737 method (using Frazier™ airflow tester) is compared to that of the ASTM D 3574 method, which is also used in polyurethane applications. This may result in the modified airflow test emerging as an industrially recognized standard method, which is less susceptible to inconsistencies that currently arise during the measurement of airflow data of foams.