THERMAL-DEGRADATION OF HIGH-PERFORMANCE POLYMERS - INFLUENCE OF STRUCTURE ON POLYIMIDE THERMOSTABILITY

This work deals with the thermostability and thermal behavior of polyi mide materials such as bismaleimide and bisnadimide, which are usually used in aeronautic and electronic applications in high temperature en vironments. The thermostability of these materials has been studied by thermogravimetry analysis (TGA) both in air and in nitrogen to determ ine thermal and thermo-oxidative phenomenon. Limiting Oxygen Index (LO I) values have been determined and compared with the LOI of a PolyEthe r Imide thermoplastic polymer. Products which are formed during therma l degradation have been identified using mass spectrometry and relatio nships between LOI. During thermal degradation, water, carbon monoxide and carbon dioxide are the most important products formed; the major organic compounds detected were aniline, polycyclic molecules and isoc yanate products. LOI increases with the number of crosslinking points, either maleimide or nadimine types. Results also show a high sensitiv ity to oxygen for these materials and they indicate that the nadimide function increases material thermostability. (C) 1996 Elsevier Science Limited