weftless rayon fabric became the first to successfully compete with cotton as rubber products reinforcement. rayon's high strength and continuous filament yarn construction resulted in its evolution as the preferred choice by the mid-1940s. nylon, invented in 1938 by dupont, was first introduced into tires during the mid-1940s. around 1970, dupont introduced an entirely new organic fiber which exhibited strength and modulus levels over twofold those of nylon and polyester. marketed as kevlar, this aramid fiber represented the first yarn to be developed directly for industrial applications