冀浩博 李坤 孙彦琳 唐晓宁 李凯 郑华 张弘

(昆明冶金高等专科学校，昆明，650033) (中国林业科学研究院资源昆虫研究所，国家林业局特色森林资源工程技术研究中心) (昆明理工大学) (中国林业科学研究院资源昆虫研究所，国家林业局特色森林资源工程技术研究中心)

By using the thermal decomposition kinetics, TG and DSC curves of lac resin from room temperature to high temperature were simultaneously monitored in oxygen atmosphere. DTG curves were plotted with corresponding software. The characteristic parameters of lac resin during aerobic thermal decomposition were determined. According to TG and DTG curves, the thermal decomposition activation energy of lac resin in oxygen atmosphere was calculated by four different mathematical methods (Kissinger, Starink, FWO, and FRL method), and the linear correlation test was carried out for the calculated results. Malek method was used to calculate and infer the thermal decomposition mathematical model of lac resin in oxygen atmosphere. The results show that the thermal decomposition reaction of lac resin in oxygen atmosphere is a two-step reaction, and the exothermic quantity of the system is higher than that of absorbed heat in the process of thermal decomposition. Because lac resin has polymer properties, the maximum decomposition rate temperature increases with the increase of heating rate. Because of the complexity of the thermal decomposition reaction system, only Kissinger and Starink methods have close linear correlation in the four mathematical methods, and the activation energies of thermal decomposition reaction are 287.192 and 287.294 kJ/mol, respectively. The results of FWO method and FRL method do not have close linear correlation, and FRL method is worse. However, the thermal decomposition mechanism can be inferred and analyzed according to the calculation results of FWO method and the shapes of TG, DTG and DSC curves. Malek method was used to calculate the most probable mechanism function of thermal decomposition reaction. The thermal decomposition reaction of lac resin in oxygen atmosphere was the closest to J-M-A equation. According to the reaction mechanism of this equation, random nucleation and subsequent growth were obtained. According to the curves of DSC, the average values of the beginning, ending and peak temperature of the viscous flow change of lac resin at the heating rates of 10, 15, 20, 25 ℃/min are 46.6 ℃, 146.5 ℃, and 80.1 ℃, respectively. The enthalpy and entropy changes of viscous flow transition at corresponding heating rate are calculated with the average values of 199.4 J/g and 0.56 J/(g·K), respectively.

紫胶树脂是少有的几类由昆虫分泌，并兼具优良成膜性、阻水性等性能的相对分子质量较大(相对分子质量介于500～2 000之间)聚合物[1]。其作为胶黏剂、密封剂、高档实木家具的表面覆层等材料应用时[2-7]，难免会暴露于空气中，若长期置于高温环境或一旦遭遇明火时，存在老化、热分解甚至燃烧的可能；而关于紫胶树脂在高温(温度>127 ℃)条件下的性能变化研究较少。所以，对紫胶树脂进行有氧条件下的热分解机理及高温热性质探索尤为必要。

常见的探索固体材料热分解性质的技术，包括热质量(TG)、差示扫描量热(DSC)、TG-DSC-傅里叶变换红外(FTIR)联用[8]等；表征参数，包括热分解温度、最大热分解速率温度、质量损失率，以及结合数学模型计算的热分解活化能等。本文采用TG进行试验[9-11]，在氧气气氛中同时监测紫胶树脂由室温至高温条件范围内的TG和DSC曲线，并应用相应软件绘制微分热质量(DTG)曲线，测定紫胶树脂有氧热分解过程的特征参数变化，包括紫胶树脂热分解之前的黏流转变过程中部分热力学参数；根据TG、DTG曲线，采用4种不同方法(Kissinger法、Starink法、FWO法、FRL法)计算紫胶树脂在氧气气氛中的热分解活化能；应用Malek法计算并推断紫胶树脂在氧气气氛中的热分解数学模型。旨……