One ancestor of the high-performance fiber-reinforced composites used today in aerospace components was a flame-resistant molding compound developed by Rexford Bradt in 1955 for the nozzles of jet-assisted take-off (JATO) aircraft.

The holder of ten U.S. patents in the compounding and processing of themoplastics, Bradt invented the process of reinforcing thermoplastics with glass fibers. In 1952 he also developed the first commercially available compound (a styrenic) and in 1954 the first compound for the advanced composites process of pultrusion (based on nylon). He founded the Fiberfill Corporation, the original compounder of reinforced thermoplastics, in Evansville, Indiana; the company is now part of DSM Engineering Plastics.