高聚物粘结剂中基于高效导热通路的设计及机制研究

The binder of polymer bonded explosive (PBX) has low thermal conductivity. When PBX is subjected to temperature impact, the heat can’t be transferred rapidly, which results in non-uniform temperature field and internal stress, and so affects the PBX performance. Owing to have large surface and extreme high thermal conductivity, adding graphene can form effective path of heat transfer in the binder, and improve the uniformity of heat distribution and rise the thermal conductivity, and is meaningful to reduce internal stress and increase the safety of weapon system. In this proposal, by the combination of tests, simulation and modelling, the manufacture processing, thermal and mechanical properties of novel graphene filled fluoropolymer binder composite will be investigated. By different modification methods of graphene surface, the composites with different interface properties will be obtained. The microstructures of graphene surface, composite and interface will be microscopically observed and characterized. The thermal and mechanical properties of composites and interface will be measured. Molecular dynamic simulation will be made to characterize thermal properties of interface. Theoretical modelling will be undertaken to predict equivalent thermal conductivity and elastic modulus. The formation process and mechanisms of highly effective network of heat transfer by graphene will be emphasized. A series of processing and properties characterization methods for novel graphene/ fluoropolymer binder composite will be established, which will provide the theoretical and experimental foundation for its engineering applications.

高聚物粘结炸药（PBX）的粘结剂热导率较低，使得PBX在经受温度冲击时，热量无法较快传递，导致炸药内部温度不均匀，产生内部热应力，影响PBX性能。由于石墨烯具有大的比表面积和极高的热导率，它可以在粘接剂内形成高效的导热通路，改善热分布的均匀性和提高热导率，对于降低内部热应力和提升武器系统安全性具有重要意义。本课题通过实验测试、数值模拟和理论分析相结合的方法，开展新型石墨烯填充氟聚物粘接剂复合材料制备工艺、热学和力学性能的研究。通过对石墨烯进行不同的表面处理，获得不同界面性能的复合材料。观测石墨烯表面、复合材料及界面的成分及微观结构，测定复合材料及界面的热学和力学性能。采用分子动力学模拟界面的热学性能，通过理论建模给出复合材料的等效热导率和弹性模量。重点研究石墨烯形成高效导热通路的工艺方法和机制，建立新型石墨烯/氟聚物粘接剂复合材料的制备与性能表征的一套方法，为其工程应用提供理论和实验依据。

针对高聚物粘结炸药（PBX）的粘结剂热导率较低的问题，本课题通过实验测试、数值模拟和理论分析相结合的方法，开展了新型石墨烯填充粘接剂复合材料制备工艺、热学和力学性能的研究。以石墨烯、氧化石墨烯、氮化硼（BN）、氧化铝（Al2O3）等为填充粒子，以氟聚物（PVDF）、端羟基聚丁二烯（HTPB）和热塑性聚氨酯（TPU）为基体，采用热压、注塑和3D打印技术制备了复合材料，并完成了热学和力学性能表征。研究发现，微波处理可以有效地获得高质量的少层石墨烯，利用甲苯二异氰酸酯toluene diisocyanate (TDI)修饰石墨烯，在石墨烯片层之间形成共价键连接。在添加13.8 wt.%粒子时，修饰石墨烯与短切碳纤维共同填充的PVDF复合材料的面外热导率达到7.96 Wm-1K-1，是纯基体的~3980%。利用异佛尔酮二异氰酸酯（IPDI）对氧化石墨烯进行表面功能化修饰，获得了具有双交联分子结构的HTPB复合材料，其热膨胀系数降低为150ppm/°C，比纯HTPB减小38.8%，变形回复率达到99.3%，动态剪切储能模量提高了105.9%。利用静电吸附和冰分离诱导自组装相结合的方法，组装成有序的三维石墨烯/氧化铝/HTPB（3DGS/Al2O3/HTPB）仿生互锁复合材料。在平行于层方向上的杨氏模量、拉伸强度和压缩模量分别提高了211%、41%和145%，热导率从HTPB的0.208W m-1 K-1提高为0.502W m-1 K-1。制备了NaNO3/GO复合氧化剂颗粒，制成了NaNO3/GO/HTPB复合含能材料，其断裂伸长率与NaNO3/HTPB相比提高了72.4%，断裂前的循环拉伸次数也显著增加，NaNO3/GO的热分解温度降低了239°C，且热分解速率随着氧化石墨烯质量分数的增加显著增大。利用三种类型苯二胺对h-BN进行表面修饰，使得表面形成H-C和B-N偶联，然后将其与液态TPU树脂共混，加热固化后形成复合材料。成功制备了石墨烯/TPU复合材料线材，实现了精细化的控制过程，所制备的复合材料热导率超过了绝大部分所报道的3D打印粒子填充复合材料，最高可达12Wm-1K-1。将高热导率的3D高导热石墨烯/TPU复合材料应用于锂离子电池的散热器外壳上，替代普通的塑料外壳，在4C充放电的情况下温度可下降5.7℃。