基于中子反射技术研究HMX炸药晶体和氟橡胶粘结剂的界面结构

The interface failure and delamination of plastic bonded explosives (PBX), related to the interfacial structure and the compatibility between explosives and polymer binders, is a common phenomenon in PBX, which can lead to the mechanical deformation and safety problem. The week adhesive ability of fluoropolymer binders result in serious delamination problem for PBX based on fluoropolymer binders, so it is significantly important to study the interfacial structure between HMX and fluoropolymer，which will help the revolution of mechanical character. Neutron reflectometry is a great tool for investigating the interfacial structure of films. In this project, we plan to prepare HMX/ fluoropolymer double layers films at different conditions, study the interfacial structure through neutron reflectometry, and master the method of experiment and data analysis. The relationship between preparing conditions and the interfacial structures will be revealed. In order to analysis the neutron experiments, special models will be proposed, which can extended the theory of neutron scattering. Nanoindentation included AFM will be performed to explore the interface failure and delamination of all the samples. All the experiments results (SEM, IR, Angle Contact Meter are also included ) will be combined to find a relationship among the preparing condition, the interfacial structure, the character of delamination.

界面脱粘是一种普遍存在于PBX炸药中能够引发材料力学性能劣化和安全性降低的现象，其发生的程度与炸药晶体和聚合物之间的融合特性和粘结结构密切相关。氟橡胶的粘结性差导致氟橡胶系列PBX炸药的界面脱粘问题尤为严重，揭示氟橡胶系列炸药的粘结结构对于提高其力学性能至关重要。中子反射技术是表征材料界面结构独特而有效的工具。本项目旨在利用提拉法制备奥克托今（HMX）/氟橡胶(F2311和F2314)双层膜作为界面结构模拟材料，找出制备条件对结构参数的影响规律；利用中子反射谱仪测试不同工艺条件双层膜的界面粘结结构，建立中子反射技术表征HMX/氟橡胶双层膜的实验方法和数据处理方法；利用纳米压痕技术研究双层膜的力学性能，获得HMX和氟橡胶之间的界面脱粘特性；综合分析双层膜的制备工艺条件、界面结构参数、脱粘特性，建立三者之间的相互关系，发现HMX和氟橡胶界面融合的一般特性。

界面脱粘是导致PBX炸药力学性能发生劣化的一种重要原因，研究炸药晶体与粘结剂之间的界面粘结结构是揭示聚合物粘结炸药类复合材料界面脱粘机制的重要科学基础。本项目基于中子反射技术发展了一种采用HMX/氟橡胶双层膜结构来模拟研究PBX中界面粘结结构的方法。研究了F2311、F2314单层膜厚度可控的提拉制备方法，通过调控溶液浓度、提拉速度可获得厚度从5.2nm到63nm可调的F2311单层膜和厚度从6.6nm到55nm可调的F2314单层膜。鉴于实际PBX制备中存在温度时效处理工艺，研究了退火温度对氟橡胶薄膜微观结构的影响：发现F2311薄膜厚度随退火温度升高而略微减小、粗糙度一直增大，可能与薄膜中溶剂挥发和分子链收缩有关；而F2314薄膜厚度在120℃退火后减小3.2%，粗糙度会从0增加至1.9nm。对比研究了热压成型和溶剂挥发制备F2314体相材料的微相分离和结晶行为，证实F2314薄膜厚度和粗糙度随退火温度的变化规律起源于F2314分子链中三氟氯乙烯的结晶和相分离，同时发现薄膜结构对F2314相分离和结晶具有限域效应，160℃退火处理可显著减缓微相分离和结晶速度，这为通过退火来增强PBX界面粘结强度提供了科学依据。研究了HMX单层膜和HMX/氟橡胶双层膜的提拉制备及界面结构表征方法，发现HMX的存在会使得F2311厚度增大、F2314厚度则变化很小，乙酸乙酯的溶解冲刷作用会使得HMX厚度只有约4nm，界面扩散厚度约为0.7 nm ~0.8nm，这可为界面粘接的理论建模提供重要参考。通过测定不同温度退火F2314样品的表面能，发现相分离和结晶状态不会影响F2314样品的表面能，推测其不影响与HMX之间的结合能。本项目所建立的制备条件与膜结构参数的关联、发展的薄膜制备方法、界面参数表征方法可拓展至药物、无机材料填充增强高分子等复合材料的界面结构研究。