Changes in the automotive supply chain over the past several years were brought about by global economic pressures, and forced some materials into tight supply as the industry started its recovery. One such material is polyamide 6,6 fiber (PA 6,6) used for airbags, which was in tight supply in 2008-09. This, with the availability of new low temperature inflators caused some airbag module manufacturers to revisit the use of polyester (PET), which had been used sporadically and in small quantities since the 1970s, although the overwhelming majority of airbags used PA 6,6.
Over the last several years PET has been adopted for use in a small number of airbag programs to reduce supply concerns, but this use has come with performance tradeoffs of higher weight, lower tear and seam properties, and other changes. Still, the lower polymer cost of PET has driven a wider evaluation.
Polyamide 6,6 and polyester are not equivalent fibers, and differences in thermal capacity, toughness, modulus, and other properties result in different fabric performance. The purpose of this paper is to raise awareness of key property differences so that the appropriate polymer is selected for each airbag.
This report is a summary of studies conducted by INVISTA S.á.r.l. to understand the potential consequences and important considerations of changing airbag cushion material from polyamide 6,6 to polyester. INVISTA is a current supplier of PA 6,6 and PET for a wide range of products including airbags, and can thus provide an unbiased view on the materials. These studies include the analysis of airbag modules that changed from PA 6,6 to PET, and laboratory tests of fibers and fabrics measuring the performance differences between these polymers.