硅基纳米含能亚稳态复合物Si@PVDF/CL-20的制备及热分解特性

Preparation and Thermal Decomposition Characteristics of Energetic Metastable Intermolecular Composite Si@PVDF/CL-20

为提高复合纳米金属材料的能量利用率,采用静电喷雾工艺制备了不同硅质量分数(20%、30%和40%)的亚稳态含能分子间复合物Si@PVDF/CL-20,采用氧弹燃烧仪测试了不同质量比PVDF/CL-20复合物的燃烧热;采用SEM分析了PVDF/CL-20复合物的形貌特征,以及Si含量对Si@PVDF/CL-20复合颗粒形貌的影响;通过同步热分析仪DSC-TG研究了不同硅含量含能复合物的热行为,并计算了其热分解动力学参数。结果表明,当PVDF/CL-20质量比为1∶6时,放热量达到了最大值,可作为包覆纳米硅粉的最优含能复合物组成比例;SEM分析发现,当硅质量分数为30%时,其复合颗粒(即Si-30%@PVDF/CL-20)的球形度最好;随硅含量增加(如60%和80%),硅沉积现象逐步加重,此时很难形成球形度较好的复合颗粒;DSC分析发现,硅质量分数为20%时,低升温速率下即可发生剧烈失控化学反应。随着硅含量进一步增加,硅粉对PVDF/CL-20复合物的分解影响较小;由Friedman方法计算得出不同硅含量复合物Si@PVDF/CL-20的表观活化能分别为470.6、182.1、91.7 kJ/mol,其中Si-20%@PVDF/CL-20分解反应物理过程不遵循单一动力学机理,Si-30%@PVDF/CL-20和Si-40%@PVDF/CL-20分解过程则可用成核和核生长模型描述。

In order to improve the energy efficiency of composite nano-metal materials,the energetic intermolecular complexes Si@PVDF/CL-20 with different silicon content(20%,30%and 40%)were prepared by electrostatic spray method.The heat of combustion of PVDF/CL-20 composites with different ratios was obtained by bomb calorimeter.The morphology of PVDF/CL-20 composite was clarified by using SEM.The effect of Si content on the morphology of Si@PVDF/CL-20 composite particles was also analyzed.The thermal behavior of energetic compounds with different silicon content was studied by DSC-TG,and the kinetic paramters of thermal decomposition were calculated.The thermal analyses indicate that when the PVDF/CL-20 mass ratio is 1∶6,the heat of combustion reaches a maximum value,which can be used as the optimal ratio incoating of nano-Si powder.The SEM results show that when the silicon content is 30%,the composite particles(Si-30%@PVDF/CL-20)exhibite the best sphericity.The DSC results show that when the silicon content is 20%,a runaway chemical reaction was likely occurred.The effect of Si powder on the decomposition of PVDF/CL-20 composite plays less significant role with the increase of content.The apparent activation energies of Si@PVDF/CL-20 composites calculated by Friedman method are 470.6,182.1,91.7 kJ/mol,respectively.The complex decomposition process of Si-20%@PVDF/CL-20 cannot be described by a single kinetic model,whereas those of Si-30%@PVDF/CL-20 and Si-40%@PVDF/CL-20 can be well described by a nucleation and growth model.