PPD is a precursor to aramid plastics and fibers such as Kevlar and Twaron. Paraglider lines are usually made from Dyneema/Spectra or Kevlar/Aramid. Stephanie Kwolek developed an aramid, or aromatic nylon named Kevlar, patented in 1966. The structure is a complex composite of carbon, aramid and polyethylene fibre reinforced plastic. Winged sheathed hull of anti-splinter coating AOD based aramid fiber. There is also an Aramid composite reinforced polymer stock available. Ballistic shields can be made out of materials such as UHMWPE or pre-preg aramid fibres. These issues led to an improved version with glass fiber instead of aramid fibers. Besides meta-aramids like Nomex, other variations belong to the aramid fiber range. They both belong to the aramid family of synthetic fibers. As fiber, it competes with aramid in bulletproof vests. The vehicles were reinforced with steel and aramid. The effect is great in aramid fibre, where hydrogen bonds stabilize the linear chains laterally. Hybrid reinforcement materials include E-glass/carbon, E-glass/aramid. Acrylic, rayon, aramid, modacrylic, and spandex are produced via this process.