Preparation and characteristics of nonflammable polyimide materials

The thermal and flame-retardant properties of homo- and copolyimides were e valuated. Those containing sulfone linkages in the backbone were found to b e more flame retardant. Both properties were dependent on the composition. A polyimide/silica nanocomposite was obtained through sol-gel processing. T he effects of the addition of silica an the dispersion, interfacial adhesio n, fire resistance, mechanical properties, and thermal stability of the com posites were investigated. SEM analysis showed a good dispersion of silica with a diameter of 50-300 nm in the organic matrices. The addition of silic a increased the fire retardancy and mechanical properties of the composites . (C) 2000 John Wiley & Sons, Inc.