BPO在等温条件下的热稳定性研究

On the thermal stability of BPO under isothermal conditions

借助差示扫描量热仪（DifferentialScanningCalorimetry，DSC）对过氧化苯甲酰（BenzoylPeroxide，BPO）的热分解过程进行研究。动态DSC结果表明，BPO的吸热峰和分锯峰重叠，因而无法通过基于放热曲线的转化率计算其动力学参数。这也表明了该物质的高度危险性。等温DSC结果表明，BPO在固态时就会发生分解，具有自催化性质，易发生热分解反应失控；该物质的熔点在90～92℃。基于等温DSC数据，利用Friedman法计算了BPO的热分解动力学参数，推导出等温诱导期与温度的函数关系，计算得到等温诱导期为7d时的环境温度（约为75℃）。使用有限元分析方法（FiniteElementAnalysis，FEA）模拟得到50kgBPO的自加速分解温度（Self-AcceleratingDecompositionTem—perature，SADT）约为79℃。

This paper is aimed to study the way on how to assess the thermal stability of benzoyl peroxide （BPO） under the isothermal con- ditions. For this purpose, we have investigated the thermal decompo- sition behavior of BPO by means of differential scanning calorimetry （DSC） in the non-isothermal modes at four heating rates （1 ℃/rain; 2 ℃/min; 4 ℃/min, and 8 ℃/min） and isothermal modes at five different temperatures （in a range of 88 - 96 ℃ ） . Since it was found that the non-isothermal DSC curves of BPO indicate that the endother- mic peak and the decomposition peak of BPO were overlapped, it means that BPO is potential of high risks. Therefore, it is impossible to get the kinetic parameters by means of conversion rate based on the exothermic curve, for the curve of BPO at 1 ℃/min indicates that BPO could be decomposed prior to the transition phase. In addition, since the heat-releasing rate of BPO began to decrease when reaching the maximum value in the isothermal DSC curve, the thermal decom- position reaction of BPO naturally belongs to the autocatalytic exother- mic reaction, and therefore, it should be regarded as being hazardous for it is unexpected for its initiation and unexpected heat evolution. We can also conclude that the melting point of BPO stands between 90 -92 ℃ . Based on the isothermal DSC data, it is possible for us to work out its thermal decomposition kinetic parameters through the dif- ferential iso-conversion （Friedman method）. Thus, the experimental data help us to find the function of isothermal induction period and the temperature at which the period tends to have an exponential function of temperature. Thus, taking the ambient temperature （ap- proximately 75 ℃ ） as a useful parameter, it can be deduced that the isothermal induction period should last about 7 days. The self-accel- erating decomposition temperature （SADT） is a highly indicative pa- rameter for assessing the safety management of self-reactive sub- stances in storage, transportation and application. By using the kinet- ic parameters, it is possible to use the AKTS-Thermal Safety Software to determine the self-accelerating decomposition temperature of BPO in a 50 kg package, whose predicted self-accelerating decomposition temperature should be 79 ℃ , a bit lower than US - TEST value. Therefore, in the actual production process, usage, storage and transportation of BPO, it is essential to improve the temperature con- trol and monitoring.