ABSTRACT
During the 1970s, some high-performance thermoplastic polymers (HPTPs) were developed, such as polysulfone (PSF), polyethersulfone (PES), PEEK, and PPS. All have an aromatic backbone structure and give good composites with excellent thermal resistance characteristics [2,3]. The unreinforced materials have a density, stiffness, and strength similar to those of the thermosets and, unless highly crystallized, a strain to failure well in excess of 10%. These polymers require high processing temperature and, in some cases, annealing periods to give optimum properties. In addition, their viscosity-temperature characteristics are such that until recently, it was not possible to impregnate fibers successfully.
