ABSTRACT
Currently, aromatic polyimides are known to be the most important high-performance polymers used as various insulative coatings for electrical wires and electronic packaging, films for flexible circuit board, thermal blanket for spacecraft and tapes, vanishes for advanced composites, and so on. This chapter deals with thermal and mechanical properties of aromatic polyimides and the relationships between ordered structure as molecular orientation and chemical structure, film preparation processes, imidization conditions, and so on. A polyimide has been generally prepared from the polycondensation reaction between an aromatic dianhydride with an aromatic diamine in a polar solvent. The thermal stability of polymers is predominantly influenced by the strength of chemical bond in a repeating structure. It is known that aromatic and heteroaromatic rings such as a benzimide ring, possess the strong bond dissociation energy. It is known that mechanical and thermomechanical properties of polyimides are greatly dominated by primary and secondary molecular structures.
