环境气氛对典型电缆外套材料热分解行为的影响

Effects of ambient atmosphere on thermal decomposition behaviors of typical cable hose material

采用热重分析方法研究环境气氛对典型电缆外套材料商用阻燃三元乙丙橡胶的热分解行为的影响。采用Kissinger-Akahira-Sunose (KAS)方法计算热解过程中的活化能,采用在线热重-红外光谱联用技术对热解逸出气体进行分析。结果表明:含氧气氛下材料的热分解速度比惰性气氛下快。惰性及含氧气氛下的热分解过程分别可分为3个及4个阶段。两种气氛下的最大质量损失速率均随升温速率升高而减小,含氧气氛下的最大及平均质量损失速率、总质量损失与活化能都比惰性气氛下的小。惰性气氛下的热解逸出气体包括3种,最大浓度排序为烃类化合物>芳香族化合物>CO2。含氧气氛下的包括4种,最大浓度排序为CO2>烃类化合物>CO>芳香族化合物。含氧气氛下的CO2的最大浓度比惰性气氛下的大,但烃类化合物及芳香族化合物的最大浓度均较小。惰性及含氧气氛下的CO2分别可能是由于成炭及燃烧反应产生的。

The effect of ambient atmosphere on thermal decomposition behavior of commercial flame retardant EPDM for typical cable jacket materials was studied by the rmogravimetry analysis(TGA). The activation energy was calculated using KissingerAkahira-Sunose(KAS) method. Volatile products generated in the thermal decomposition process were analyzed using online TG analyzer instrument coupled with Fourier Transform Infrared(TGAFTIR). Results showed that the thermal decomposition rate in oxygenous atmosphere was larger than that in inert atmosphere. The thermal decomposition in inert and oxygenous atmosphere showed a three-stage and four-stage process, respectively. The maximum mass loss rate(MLR) decreased with heating rate in both atmospheres. The maximum and average MLR, the total mass loss and the activation energy in oxygenous atmosphere were all less than those in inert atmosphere. Three volatile products occurred in inert atmosphere, and the maximum amount of these three volatile products in the order of most to least was aliphatic compounds > aromatic compounds > CO2. Four volatile products appeared in oxygenous atmosphere, and the maximum amount of these volatile products in the order of most to least was CO2> aliphatic compounds > CO > aromatic compounds. The maximum amount of CO2 in oxygenous atmosphere was larger than that of inert atmosphere. However, the maximum amount of aliphatic compounds and aromatic compounds in oxygenous atmosphere was less than those in inert atmosphere. It was indicated that the carbon dioxide may be generated from the char formation and combustion reaction in inert and oxygenous atmosphere, respectively.