The polymer used for making missiles, solid propellant rocket motors and pressure vessels is

Polyacrylonitrile (PAN) is a resinous, fibrous, or rubbery organic polymer. PAN fibres are the chemical precursor of high-quality carbon fibre. It is chemically modified to make the carbon fibres found in plenty of both high-tech and common daily applications such as civil and military aircrafts,  primary and secondary structures, missiles, solid propellant rocket motors, pressure vessels, fishing rods, tennis rackets, badminton rackets and high-tech bicycles.