Silicones and the History of Airbags
Silicones and the History of Airbags
For 20 years, Elkem Silicones has been playing a major role in the conception of lighter, safer and more durable airbag cushions for our security.
In the late 1930’s, the growing automobile fleet brought an unavoidable increase of major road injuries, leading automobile manufacturers to work intensely on their cars’ safety. This is how crash tests and their notorious dummies appeared in the 1950’s in the United States, and at the same time the first patents for airbag systems were filed.
The first step in airbags history was the development of a driver’s cushion, first commercialized with Ford and General Motors cars in the 1970’s. The idea was almost abandoned then because of the alarming number of injuries linked to failures of the airbag system. However, Mercedes Benz engineers did not give up on the concept and the airbag finally was introduced with full commercial success in the 1980’s with the Mercedes’s Class S, as a part of a global restraint system with the seatbelt.
An airbag is a complex apparatus, formed by a textile cushion, a pyrotechnic inflator, and a lot of electronics! Moreover, it took quite long for engineers to figure out how to characterize a crash, define the proper deployment speed, and manage maintenance and durability of the whole system, while making sure it would deploy when needed!
Until the 1990’s, airbag cushions were coated with solvent-based Neoprene, a synthetic rubber known for its insulating properties. However, manufacturers soon realized that Neoprene was not aging well, making airbags out of service long before the car itself. Furthermore, Neoprene had to be applied at high coat weights, making the cushions more expensive, and the module bulkier.
When airbag modules were introduced in the smaller cars manufactured in Europe, Silicones naturally appeared to be the best material to replace Neoprene in the coatings of airbags: only half of the product quantity was needed initially to coat the textile effectively, and Silicones could be in the form of a solventless, liquid silicone rubber. Easy to process, Silicones enabled the making of more compact textile cushions, and therefore smaller airbag modules to fit into that little Renault Twingo (in 1995)!
More importantly, Silicones exhibited a much better aging behavior than Neoprene, perfectly withstanding heat/cold/humidity accelerated aging cycles, making the association polyamide textile and silicone a very durable component of airbag modules. In the case of an accident, whether a 10 year-old car or a brand new one, our Silicones ensure that the airbag deploys properly.
After the proven success of drivers’ airbags used in conjunction with seatbelts, and pushed by the raising awareness about road safety, automotive engineers developed additional safety modules to protect the other occupants of the automobile.
Soon after appeared passenger airbags, to complement the frontal protection of occupants, and in the 1990’s appeared side airbags for lateral impacts. Initially protecting hip and thorax, they evolved to protect also the head, before manufacturers introduced the concept of side curtain airbags. These long airbags unfold from the roof and cover the side window area to protect the head of the driver and front passenger, and also now rear passengers.
Additional airbag types were developed in the years 2000s and 2010s, such as knee airbags, inflatable seat belts, or roof airbags such as the one fitted in the Citroen C4 Cactus (2014). In 2012 Volvo introduced to its V40 model, a large external airbag cushion that inflates to lift the hood and protect the head of a pedestrian in case of impact. Airbag systems are used also to make avalanche airbags, motorcycle airbags, and even a helmet for cyclists made of an airbag cushion (Hövding) that deploys in case of accident.
In all of these different airbags, silicones are used to convey thermal protection, controlled permeability and mechanical performance. We have evolved our silicone products over time to meet these exciting challenges and transformations. But that story is going to be for the next episode…