Thermal properties and flame retardancy of polycarbonate/hydroxyapatite nanocomposite

The thermal degradation of polycarbonate (PC) and polycarbonate/hydroxyapatite (PC/HAP) composite was investigated by the thermogravimetric analysis (TGA) and the decomposition activation energy was calculated by Kissinger method. It was found that the first step decomposition activation energy (E-a1) was higher than that of pure PC while the second step decomposition (E-a2) decreased a little. The limiting oxygen index (LOT) of PC/HAP composite with 0.5 wt % HAP reached 34. The carbon char of PC and PC/HAP composite after cornbustion was analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and flourier transform infrared spectroscopy (FTIR) and similar morphology, components, and the same functional groups were found in the char residues. Based on these results, it can be concluded that a low content of HAP in PC matrix can significantly improve the thermal properties and flame retardancy of the composite. (c) 2008 Wiley Periodicals, Inc.