For the last three decades, increasing need in the high technology industries (space, micro and nano electronics, civil transportation, planes, automotive, membranes, fuel cells, etc.) has been the driving force for the development of new polymeric systems and materials combining both thermal mechanical and temperature resistance and also properties others such as lightweight, high corrosion resistance, good wear properties, dimensional stability, low flammability, separation properties, moisture resistance, insulating properties and ability to be transformed with conventional equipment. In fact all these properties were unavailable in conventional materials but may be covered by aromatic and heterocyclic linear and thermosetting resins such as: acetylene terminated resins, bismaleimides, polyetherimides, polyamide-imides,polybenzimidazoles,polyetherketones,polyphenylquinoxalines, polyphenylensulfides, polysulfones & derivatives, polystyrylpyridines, fluoropolymers, silicones, etc. This book describes the properties and application all such types of high performance polymers.