十溴二苯醚热解动力学及在聚苯乙烯中的热解行为

摘要

十溴二苯醚(decaBDE)是多种聚苯乙烯(PS)类塑料阻燃添加剂,其热解动力学对开发新型高效的电子塑料安全处置技术具有十分重要的意义,为此采用普适积分法成功关联了氮气中decaBDE的热解动力学参数.结果表明:固体decaBDE在306℃时熔融为液相并在400～450℃进一步汽化为气相,热重/红外(TG/IR)分析表明,其气相产物组成具有与decaBDE相同的红外特征；decaBDE热解过程可用三维扩散模型关联.进而通过对比分析decaBDE、PS和含decaBDE的阻燃PS样品的TG实验结果,发现阻燃塑料样品在热解时存在decaBDE与PS间的相互作用,表现为热解起始温度的降低和终止温度的升高.TG/IR分析表明:阻燃塑料样品的热解气相产物中不存在游离的HBr,decaBDE热解时产生的活性基团改变了PS的降解反应历程,使其气相产物具有与1,3-二苯基丁烷类似的红外特征.%Decabromodiphenyl ether (decaBDE) is one of the most popular flame retardants used with polystyrene. The interest in the thermal decomposition of decaBDE has intensified due to its potential production of polybrominated dibenzo-p-dioxins (PBDD) or dibenzofurans (PBDF) in the thermal recycle of plastic waste. Kinetics of thermal decomposition of decaBDE was studied by non-isothermal thermogravimetric analysis (TGA). The three-dimensional diffusion model was found to be the best correlation of TGA data by the general integration method. The activity energy and logarithmic pre-exponential factor were found to be 122. 7 kJ · mol-1 and 74. 3 s-1 in TGA of decaBDE. In the process of thermal decomposition of decaBDE in the atmosphere of nitrogen, solid decaBDE melt at 306℃ and then vaporized in the temperature range of 400-450℃. When PS was blended with decaBDE, the decomposition temperature of the mixture was lower than that of virgin PS and a higher temperature was needed to complete pyrolysis. The infrared spectral characteristics of 1,3-diphenylbutane was detected in the pyrolysis vapor-phase products of the mixture, whereas styrene was usually found in the pyrolysis product of PS. It indicated that the active groups released from decaBDE changes the path of depolymerization in thermal decomposition of PS.