火灾频发导致人类的生命及财产安全受到极大威胁，快速高效扑灭火灾以最大程度减少损失意义重大。温敏性水凝胶兼具“溶胶-凝胶”后相变吸热、高汽化潜热和高粘附性等特点，在火灾防控领域具有较好的应用前景。本文首次在甲基纤维素（MC）中加入聚丙烯酸钠（PAAS）、氯化镁（MgCl₂）以制备温敏性水凝胶，探讨其对木垛和煤体两种不同燃烧形式固体火灾的灭火效果，揭示其灭火机理。

       采用单因素法研究了三元体系下各组分浓度对凝胶时间、凝胶强度、常温粘度及临界转变温度等参数的影响，从宏观和微观两个角度揭示了凝胶转变机理。采用CCD响应曲面法对配方进行优化设计，优选制备比例为MC：PAAS：MgCl₂=1.3：2.11：16。通过失水率测试、傅立叶红外光谱（FT-IR）及扫描电镜（SEM）等方法表征了凝胶性能。

       MC-PAAS-MgCl₂凝胶灭木垛火效果，通过降温速率、火焰面积和灭火时间变化等参数表征灭火效率，为温敏性水凝胶灭火工艺及参数设置提供依据。采用2wt%的温敏性水凝胶进行灭1A木垛火实验，结果表明：温敏性水凝胶灭火后无复燃现象发生，由于溶胶-凝胶转变过程可逆，灭火结束后随着火场温度降低温敏性水凝胶逐渐变稀，残存的灭火剂容易处理，灭火效率较高。

       通过程序升温实验测试了三种不同变质程度煤样经温敏性水凝胶处理前后的气体产物、阻化率及耗氧速率等参数，分析了胶体在煤自燃过程中的抑制作用。搭建中型煤火试验台（装煤量200 kg）进行了胶体灭煤火性能测试，结果表明：温敏性凝胶注入高温煤体后相变降温，吸收了煤体火区的高温热能，降低了煤氧复合速度，致使煤火熄灭。本文的研究成果为凝胶类灭火剂的研究与应用提供了新的思路。

        The frequent occurrence of fires has greatly threatened human life and property safety. It is of great significance to quickly and efficiently extinguish fires to minimize losses. Thermosensitive hydrogels have good application prospects in the field of fire prevention and control due to their characteristics of "sol-gel" post-phase transition endothermic, high latent heat of vaporization, and high adhesion. In this paper, sodium polyacrylate (PAAS) and magnesium chloride (MgCl₂) were added to methylcellulose (MC) for the first time to prepare thermosensitive hydrogel to discuss their fire-extinguishing effects on wood stacks and coal and revealt their fire-extinguishing mechanism.

        The effects of the concentration of each component on the parameters of gelation time, gel strength, room temperature viscosity and critical transition temperature were tested by single factor method, and the gel transition mechanism was revealed from both macroscopic and microscopic perspectives. The formula was optimized by CCD response surface method, and the preferred preparation ratio was: MC: PAAS: MgCl₂=1.3: 2.11: 16. The gel properties were characterized by water loss rate test, fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM).

        A small fire extinguishing test bench was built to test the fire extinguishing effect of three concentrations of MC: PAAS: MgCl₂ gel, and the fire extinguishing efficiency was characterized by parameters of cooling rate, flame area and fire extinguishing time, which can provide the basis for fire extinguishing process and parameter setting of thermosensitive hydrogel. The 1A wood stack fire extinguishing experiment was carried out with 2wt% thermosensitive hydrogel. The results showed that there was no re-ignition phenomenon after the thermosensitive hydrogel extinguished the fire. Since the sol-gel transition was reversible, the thermosensitive hydrogel gradually became thinner as the temperature of the fire field decreases after the fire extinguishing, the remaining fire extinguishing agent was easy to handle, and the fire extinguishing efficiency was high.

         The parameters such as gas product, resistance rate and oxygen consumption rate before and after treatment with thermosensitive hydrogels were tested by temperature-programmed experiments, and the inhibitory effect of colloids on coal spontaneous combustion was analyzed. A medium-sized test bench (with a coal loading capacity of 200 kg) was built to test the fire extinguishing performance of colloial coal. The results showed that the thermosensitive gel was injected into the high-temperature coal after phase change and cooled down, absorbed the high-temperature heat energy in the fire area, and reduced the coal-oxygen recombination speed, and caused the coal fire to extinguish. The research results of this paper provide new ideas for the research and application of gel fire extinguishing agents.

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