PBO纤维的热降解过程分析

Thermal Degradation Process of PBO Fiber

运用裂解-色谱/质谱(Py-GC/MS)、热失重-红外(TGA-DTA/FT-IR)、热失重-质谱(TGA-DTA/MS)等联用技术分析聚对苯撑苯并双唑(PBO)纤维的热降解行为。其中,PBO纤维在Py-GC/MS中迅速裂解产生的碎片记录了分子链断裂的过程,而在TGA-DTA/FT-IR、TGA-DTA/MS中连续升温的热降解特征及其释放物反映了纤维受热后分子链的断裂、重组等过程。升温到1 000℃时,在惰性气体中,PBO纤维的热失重剩余量为76.5%,而在空气中几乎完全失重,氧化作用对纤维的失重影响很大。在两种气氛下降解产物均以小分子物质为主,其中CO2占最大比例。

The thermal degradation behaviors of Poly（p-phenylene-2,6-benzoxazole）（PBO）fiber were studied using pyrolysis-gas chromatography/mass spectrometry （Py-GC/MS）, thermogravimetric analysis coupled with mass spectrometry （TGA-DTA/MS） and thermogravimetric analysis coupled with Fourier transform infrared spectroscopy（TGA-DTA/FT-IR）. Py-GC/MS affords the advantages to detect temporarily thermal stability and volatile fragments, and the rupture process of molecular chain can be recorded. TGA-DTA/FFIR and TGA-DTA/MS undertake the continuous heated processes,and the thermal properties and volatiles illustrate the chemical reactions of decomposed PBO, which involving scission, recomposition and so on can be illustrated. Ascending the temperature to 1 000 ℃, PBO fiber keeps the residues of 76.5% in inert gas and almost losses all mass in air. Oxidation takes a great effect on mass loss. In both inert gas and air, the little molecular volatiles of thermal degradation are the main products and CO2 keeps the largest fraction.