High-Temperature Chemical and Microstructural Transformations of a Nanocomposite Organoceramic

This paper describes the microstructural and chemical transformations occurring at high temperatures in polymer /inorganic crystal nanocomposites referred to as organoceramics. The organoceramic investigated consists of alternating layers of poly(vinyl alcohol) (PVA) and the layered double hydroxide [Ca sub 2 Al(OH) sub 6 ] exp + [(OH)mult3H sub 2 o] exp - , with a structural repeat distance of approx18 A. The nanocomposite was heated to various temperatures up to 1000 deg C and analyzed using x-ray diffraction, infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and chemical analysis. The layered structure of the organoceramic was found to be stable up to a temperature of 400 deg C, whereas the pure layered double hydroxide lacking organic material decomposed at 125 deg C. The high thermal stability of the organoceramic nanocomposite may arise from an extensive and strongly bonded interface between organic and inorganic components. Interestingly, the organoceramic heated to 100 deg C transforms into an inorganic solid which has a different phase composition than the layered double hydroxide heated to the same temperature.