【作者】 胡敏；

【导师】 李治； 步磊；

【作者基本信息】 中南大学 ， 资源与环境（专业学位）， 2025， 硕士

【摘要】 SiO₂ 气凝胶（SA）是一种优异的保温隔热材料,但其疏水改性过程中引入的有机基团会带来的潜在火灾风险,制约其推广应用。本研究通过引入还原氧化石墨烯（rGO）制备了rGO/SiO₂气凝胶复合材料（rGO/SA）,引入植酸（PA）制备了PA/SiO₂气凝胶复合材料（PA/SA）,分别研究了rGO和PA对SA的热安全性能的影响。在此基础上,利用植酸对氧化石墨烯进行还原改性（PA-GO）,制备了PA-GO/SiO₂气凝胶复合材料（PA-GO/SA）,实现了SA热安全性能的提升。研究分析了rGO、PA、PA-GO对气凝胶复合材料物化性质、隔热、热稳定性以及阻燃特性的影响机制,明晰了热安全调控机制。主要研究成果如下:（1）通过常压干燥法制备了rGO/SA复合材料,rGO/SA保持着低密度（0.10 g/cm³）、低热导率（22.9 m W/（m·K））和高比表面积（863.4m²/g-913.1 m²/g）。当rGO添加量为0.45%时,rGO/SA的初始分解温度对比纯SA升高了129.8℃,总热值和总热释放量分别降低了8.0%和25.4%。适量的rGO能够提升SA的热稳定性和阻燃性能,其作用机制是rGO在基体中质量屏障效应与高导热性的协同竞争。（2）使用PA作为催化剂和阻燃剂制备了PA/SA复合材料,PA/SA保持了低密度（0.09 g/cm³）和低热导率（23.2 m W/（m·K））。PA的加入使SA的分解温度提高208.1℃,质量残留率提高到92.6%,GCV最大降幅为51.6%,总热释放量和热释放速率峰值分别降低了63.6%和28.7%。PA通过在气相中捕获材料燃烧过程中产生的自由基,淬灭燃烧链式反应;在凝聚相中促进SA的快速脱水和炭化,建立物理屏障,达到阻燃效果。（3）制备了具有低密度（0.12 g/cm³）和低热导率（24.1 m W/（m·K））的PA-GO/SA气凝胶复合材料。PA-GO/SA-0.45%初始分解温度提高了62.5℃,热释放速率峰值降低了13.4%,总燃烧热值降幅为13.8%,热稳定性和阻燃性能显著提升。结合rGO和PA的阻燃机理推测出PA-GO的阻燃机理为:在凝结相,石墨烯片层形成物理屏障、植酸促进碳化形成炭层,阻挡热量传递;在气相,石墨烯和植酸通过捕获自由基终止链式反应,释放惰性气体,抑制燃烧反应进行。图56幅,表8个,参考文献173篇更多还原

【Abstract】 SiO₂ aerogel（SA）is an excellent thermal insulation material,but the potential fire risks introduced by organic groups during its hydrophobic modification process restrict its large-scale application.In this study,reduced graphene oxide（rGO）was introduced to prepare rGO/SiO₂ aerogel composites（rGO/SA）,and phytic acid（PA）was used to fabricate PA/SiO₂ aerogel composites（PA/SA）,systematically investigating the effects of rGO and PA on the thermal safety performance of SA.On this basis,graphene oxide was reductively modified with phytic acid（PA-GO）to prepare PA-GO/SiO₂ aerogel composites（PA-GO/SA）,achieving enhanced thermal safety performance of SA.The study analyzed the influence mechanisms of rGO,PA,and PA-GO on the physicochemical properties,thermal insulation,thermal stability,and flame retardant characteristics of the aerogel composites,and clarified the thermal safety regulation mechanism.The main research achievements are as follows:（1）The rGO/SA composite was prepared via atmospheric pressure drying,maintaining low density（0.10 g/cm³）,low thermal conductivity（22.9m W/（m·K））,and high specific surface area（863.4 m²/g–913.1 m²/g）.When the rGO loading was 0.45%,the initial decomposition temperature of rGO/SA increased by 129.8℃ compared with pure SA,while the total heat value and total heat release decreased by 8.0%and 25.4%,respectively.Appropriate amounts of rGO can improve the thermal stability and flame retardancy of SA,with the mechanism attributed to the competitive synergy between the mass barrier effect and high thermal conductivity of rGO in the matrix.（2）Using phytic acid as both an acid catalyst and flame retardant,the PA/SA composite was prepared,retaining low density（0.09 g/cm³）and low thermal conductivity（23.2 m W/（m·K））.The addition of PA increased the aerogel’s decomposition temperature by 208.1℃,raised the mass residue rate to 92.6%,and caused a maximum decrease of 51.6%in the gross calorific value（GCV）.The total heat release and peak heat release rate decreased by 63.6%and 28.7%,respectively.The flame retardant mechanism of PA in SA was revealed as follows:in the gas phase,PA captures free radicals generated during combustion to quench the chain reaction;in the condensed phase,it promotes rapid dehydration and carbonization of SA,forming a physical barrier to achieve flame retardancy.（3）The PA-GO/SA aerogel composite exhibited low density（0.12 g/cm³）and low thermal conductivity（24.1 m W/（m·K））.With a 0.45%PA-GO loading,the initial decomposition temperature increased by 62.5℃,the peak heat release rate decreased by 13.4%,and the total combustion heat value decreased by 13.8%,significantly enhancing thermal stability and flame retardancy.Combining the flame retardant mechanisms of rGO and PA,the flame retardant mechanism of PA-GO was proposed as follows:in the condensed phase,graphene sheets form a physical barrier,and phytic acid promotes carbonization to form a char layer,blocking heat transfer;in the gas phase,both graphene and phytic acid terminate chain reactions by capturing free radicals,inhibiting combustion.更多还原