近年来，随着我国电力需求快速增长，电气系统的安全问题日益突出，尤其是在有限空间内的电气火灾成为一大隐患。全氟己酮（C₆F₁₂O）作为一种新型环保灭火剂，具有优异的灭火性能和环境友好性，但其易挥发性和低浓度下的助燃效应限制了其应用。本研究旨在通过微胶囊技术封装全氟己酮基复合灭火剂，开发一种高效、环保、稳定的新型灭火材料，为有限空间电气火灾防控提供创新解决方案。论文围绕微胶囊复合灭火芯材灭火特性、聚脲微胶囊壁材制备与优选、含复合芯材聚脲微胶囊制备方法、含复合芯材微胶囊结构强化及灭火机理等方面展开研究，主要取得如下成果：

通过改进标准杯式燃烧器实验系统，系统研究了C₆F₁₂O与顺式六氟丁烯（C₄H₂F₆）、2-溴-3,3,3-三氟丙烯（C₃H₂BrF₃）和全氟三乙胺（C₆F₁₅N）三种高沸点环保型灭火剂的复配效果，掌握其灭火特性。结果表明，C₆F₁₂O在低浓度下（<3%）对正庚烷火焰存在明显的助燃效应，最大火焰高度增加120.05%。当C₆F₁₂O与C₆F₁₅N复配时表现出最佳的协同灭火效果，当C₆F₁₅N摩尔分数为10%时，协同指数达到0.94，灭火浓度降低至5.35%。相比之下，C₆F₁₂O与C₃H₂BrF₃的组合虽然在低浓度下表现出一定的协同效应，但同时也增强了火焰燃烧强度。而C₆F₁₂O与C₄H₂F₆的复合则未表现出明显的协同作用，反而增强了燃烧现象。综合考虑灭火效能、环境友好性和安全性，最终选择C₆F₁₂O与C₆F₁₅N的复合灭火剂作为微胶囊芯材。

采用沉淀聚合法制备了异佛尔酮二异氰酸酯（IPDI）与六种不同多元胺（EDA、DAB、HMD、PPD、DETA、TETA）的聚脲壁材。通过表面氨基含量测定、形貌分析、红外光谱分析、X射线衍射分析和热重分析等方法对聚脲壁材进行了综合表征。研究发现，TETA制备的聚脲壁材表现出最优异的综合性能，具有均匀球状形貌（平均粒径43.92 μm）、低结晶度（9.8%）和良好热稳定性（初始分解温度334.7 ℃），因此被选为最适合的微胶囊壁材。

建立了含复合芯材微胶囊的质量评价方法，包括粒径分布、复合芯材包覆率和储存稳定性的测定方法。通过优化制备工艺参数，成功制备出含复合芯材的聚脲囊壳微胶囊。采用响应面分析法确定了最佳制备条件：乳化转速3000 rpm、乳化剂用量0.4g、水油比为3:1、聚合转速300 rpm。在此条件下，微胶囊的理论破裂温度为215.1 ℃，包覆率为59.6%。储存稳定性研究发现制备的微胶囊在60 d常温储存和24 h加速储存下的质量损失率均超过15%，表明单层线形结构的聚脲微胶囊外层囊材的强度和致密性不高，渗透性较强，长期储存稳定性低，无法有效保护挥发性强的液体复合芯材。并通过对聚脲囊壳微胶囊化过程与机理进行探讨，揭示了聚脲囊壳的自组装过程在微胶囊化中的作用。

设计并制备了三种不同结构（网状交联、聚脲/聚氨酯复合和聚脲/聚氨酯双层网状）强加的含复合芯材微胶囊。通过扫描电镜、激光粒度分析、傅里叶红外光谱、热重分析和热物性参数测试等方法对微胶囊进行了全面表征。结果显示，聚脲/聚氨酯双层网状结构微胶囊表现出最优异的综合性能，破裂温度262.3 ℃，包覆率69.1%，24 h加速储存后损失率仅7.31%。热物性分析显示，随结构复杂度增加，热扩散系数降低（0.1265 mm²/s至0.0883 mm²/s），比热容增加（1.21 J/(g·K)至1.56 J/(g·K)）。

通过自建微型有限空间灭火实验装置评估了不同结构微胶囊的灭火性能。首先通过通风条件测试，发现开6孔为最佳通风条件，既能保证有限空间的特性，又能有效防止因自然窒息而导致的非预期灭火。通过分析火焰形貌、火场氧浓度、温度分布和灭火时间等参数，系统评估了不同结构微胶囊的灭火性能。结果表明，不同结构微胶囊表现出不同的灭火特性，聚脲/聚氨酯双层网状结构微胶囊灭火时间最长（25 s），但表现出最强的温度耐受性（378.0 ℃）和最持久的氧气抑制效果（11.7%）。线性结构微胶囊灭火速度最快（18 s），但温度控制和氧气抑制效果较弱。

运用量子化学计算方法，对C₆F₁₂O和C₆F₁₅N的分子结构、前线轨道、能隙和静电势进行了深入分析，发现C₆F₁₂O主要通过羰基与OH自由基反应，而C₆F₁₅N则主要通过中心氮原子参与灭火过程。两种物质在微观层面上表现出互补的化学反应机制和协同的物理冷却效应，揭示了含复合灭火芯材的微观灭火机理。

本研究开发的复合芯材温敏微胶囊灭火材料，解决了C₆F₁₂O易挥发和低浓度助燃的问题，显著提高了灭火效率和稳定性。研究成果为有限空间电气火灾防控提供了新型高效灭火方案，同时也为微胶囊技术在消防领域的应用拓展了新的思路。

In recent years, with the rapid growth of China’s electric power demand, the safety of the electrical system is becoming more and more prominent, especially the electrical fire in the limited space has become a major hidden danger. Perfluorohexanone (C₆F₁₂O), as a new type of environmentally friendly extinguishing agent, has excellent fire extinguishing performance and environmental friendliness, but its volatility and combustion-enhancing effect at low concentrations limit its application. The aim of this study is to develop a new type of highly efficient, environmentally friendly and stable fire extinguishing material by encapsulating perfluorohexanone-based composite fire extinguishing agent through microencapsulation technology to provide innovative solutions for the prevention and control of electrical fires in limited spaces. The paper focuses on the fire extinguishing characteristics of composite fire extinguishing core materials, optimal selection of polyurea wall materials, preparation methods of polyurea microcapsules containing composite core materials, reinforcement of microcapsule structures, and fire extinguishing mechanisms. The main achievements are as follows:

By improving the experimental system of standard cup burner, the effect of compounding C₆F₁₂O with three high-boiling-point environmentally friendly fire extinguishing agents, namely, cis-hexafluorobutene (C₄H₂F₆), 2-bromo-3,3,3-trifluoropropene (C₃H₂BrF₃), and perfluoro-triethylamine (C₆F₁₅N), has been investigated in a systematic way. The results showed that C₆F₁₂O at low concentration (<3%) had an obvious ignition-assisting effect on n-heptane flame, and the maximum flame height increased by 120.05%. The best synergistic fire extinguishing effect was exhibited when C₆F₁₂O was compounded with C₆F₁₅N, and the synergistic index reached 0.94 and the extinguishing concentration was reduced to 5.35% when the C₆F₁₅N molar fraction was 10%. In contrast, the combination of C₆F₁₂O and C₃H₂BrF₃ exhibits a certain synergistic effect at low concentrations, but also enhances flame combustion intensity. The composite of C₆F₁₂O and C₄H₂F₆ did not show a significant synergistic effect, but instead enhanced the combustion phenomenon. Taking into account the fire extinguishing efficiency, environmental friendliness, and safety, the composite fire extinguishing agent of C₆F₁₂O and C₆F₁₅N was ultimately chosen as the microcapsule core material.

Polyurea wall materials made of isophorone diisocyanate (IPDI) and six different polyamines (EDA, DAB, HMD, PPD, DETA, TETA) were prepared by precipitation polymerization method. The polyurea walls were comprehensively characterized by surface amine content determination, morphological analysis, infrared spectral analysis, X-ray diffraction analysis and thermogravimetric analysis. It was found that the polyurea walls prepared by TETA exhibited the most excellent comprehensive performance with uniform spherical morphology (average particle size of 43.92 μm), low crystallinity (9.8%), and good thermal stability (initial decomposition temperature of 334.7 °C), and thus were selected as the most suitable microencapsulated wall materials.

A quality evaluation method for microcapsules containing composite core materials was established, including the determination of particle size distribution, composite core coating rate and storage stability. By optimizing the preparation process parameters, polyurea capsules containing composite core materials were successfully prepared. Response surface analysis was used to determine the optimal preparation conditions: emulsification speed of 3000 rpm, emulsifier dosage of 0.4 g, water-to-oil ratio of 3:1, and polymerization speed of 300 rpm. Under these conditions, the theoretical rupture temperature of the microcapsules was 215.1 °C, and the encapsulation rate was 59.6%. The storage stability study found that the mass loss rate of the prepared microcapsules was more than 15% under 60 days of ambient storage and 24 accelerated storage, indicating that the strength and density of the outer layer material of the single-layer linear structure polyurea microcapsules are not high, and the long-term storage stability is low, which cannot effectively protect the volatile liquid composite core material. And by exploring the process and mechanism of microencapsulation of polyurea capsule shells, the role of the self-assembly process of polyurea capsule shells in microencapsulation was revealed.

Microcapsules containing composite cores with three different structures (reticulated cross-linking, polyurea/polyurethane composite and bilayer reticulation) were designed and prepared. The microcapsules were fully characterized by scanning electron microscopy, laser particle size analysis, Fourier infrared spectroscopy, simultaneous thermal analysis and thermophysical parameter testing. The results showed that the polyurea/polyurethane bilayer mesh structure microcapsules exhibited the most excellent comprehensive performance, with a rupture temperature of 262.3°C, an encapsulation rate of 69.1%, and a loss rate of only 7.31% after 24-h accelerated storage. Thermophysical analysis showed that the thermal diffusion coefficient decreased (0.1265 mm²/s to 0.0883 mm²/s) and the specific heat capacity increased (1.21 J/(g·K) to 1.56 J/(g·K)) with increasing structural complexity.

The fire extinguishing performance of microcapsules with different structures was evaluated by a self-built experimental setup for fire extinguishing in miniature confined spaces. Firstly, through the test of ventilation conditions, it was found that opening 6 holes was the optimal ventilation condition, which could ensure the characteristics of the enclosed space and effectively prevent unintended fire extinguishing due to natural asphyxiation. The fire extinguishing performance of microcapsules with different structures was systematically evaluated by analyzing flame morphology, oxygen concentration in the fire scene, temperature distribution, and extinguishing time. The results showed that microcapsules with different structures exhibited different fire extinguishing characteristics. The polyurea/polyurethane double-layer network structure microcapsules had the longest fire extinguishing time of 25 s, but exhibited the strongest temperature tolerance (378.0 ℃) and the most persistent oxygen suppression effect (11.7%). Linear structure microcapsules have the fastest fire extinguishing speed (18 s), but their temperature control and oxygen suppression effects are weaker.

Using quantum chemical calculations, the molecular structures, front orbitals, energy gaps and electrostatic potentials of C₆F₁₂O and C₆F₁₅N were analyzed in depth, and it was found that C₆F₁₂O reacts with OH radicals mainly through carbonyl groups, while C₆F₁₅N participates in the fire extinguishing process mainly through the central nitrogen atom. The two substances showed complementary chemical reaction mechanisms and synergistic physical cooling effects at the microscopic level, revealing the microscopic fire extinguishing mechanism of the composite fire extinguishing core containing composite fire extinguishing materials.

The composite core temperature-sensitive microcapsule fire extinguishing material developed in this study solves the problem of volatile C₆F₁₂O and low concentration of combustion-assisted problems, and significantly improves the fire extinguishing efficiency and stability. The research results provide a new type of efficient fire extinguishing solution for the prevention and control of electrical fires in limited spaces, and also expand new ideas for the application of microcapsule technology in the field of fire protection.