Another timeless find by the DuPont company came in 1965 in the form of a seemingly useless liquid.
Poly-paraphenylene terephthalamide, or Kevlar, was discovered by Stephanie Kwolek while searching for a way to curb expenses during an impending fuel shortage. The intention was to use it in tyres to bring down their weight, up their durability and decrease consumption.
The solution first discovered was discarded but after insistence from Kwolek was tested in the Spinneret – a device that spun the liquid solution – and it was found that the liquid formed strong fibres. Think a candy floss spinner that spins out sugar strands. This process is very costly when producing Kevlar due to the solution needing to be kept insoluble during the process.
Kevlar has a tensile strength (think stretch strength instead of compress strength) of 3,620 MPa which is really, really high. This strength is developed through many inter-chain bonds. A similar fibre was later patented by Akzo which resulted in many legal battles.
Kevlar is mostly associated with it’s military or SWAT use, which it is highly effective for, but there are myriad uses for this hardy fibre. It has been used in racing tyres, for sailing boats, in bows for archery and several other sports that require agile, yet strong, materials.
Kevlar is even used in the music industry in both instruments and other hardware. Due to its useful acoustic properties, it is found in speaker cones and even wound into audio cables to make them more durable. The extreme tension it can take makes it ideal for snare drums, making the sound cleaner and the instrument last longer.
Plenty more practical examples of Kevlar can be found in garden gloves, long sleeves, jackets and other clothing that protect us from nasties without turning us into beasts of burden.