【作者】 刘涛；

【导师】 王明辉； 李志刚；

【作者基本信息】 吉林大学 ， 材料加工工程， 2025， 硕士

【摘要】 随着工业化进程的加速,发展绿色、低碳的保温隔热材料对实现能源高效利用和可持续发展具有重要意义。但当前市面上的保温材料均存在一定局限性,因此,开发一种新型、轻质、稳定且高效的隔热材料有助于可持续发展战略的实施。二氧化硅气凝胶内部由纳米级别的孔隙结构组合而成,是具有低密度、高比表面积、高孔隙率、低导热系数等独特性质的一种新型隔热材料。但制备工期长、机械性能差等性质限制了实际应用。因此,本文对二氧化硅气凝胶的化学组成和网络结构进行了精确调控,并结合多尺度增强策略,分别选用纤维素（微米级）和碳纤维毡（宏观级）作为增强相,构建了分级增强体系。系统地研究了纤维含量等制备参数对复合材料微观结构、力学性能及热学性能的影响规律,以解决二氧化硅气凝胶及复合材料在实际应用中的掉粉掉渣问题。具体研究工作如下:优化正硅酸乙酯（TEOS）基SiO₂气凝胶的制备工艺,在常温常压条件下实现了快速制备。经过调控水解、缩聚阶段pH值和温度,以及TEOS、EtOH和H₂O的摩尔比,可将传统制备周期从5-7天缩短至48小时。所得SiO₂气凝胶具有优异的性能:密度低至0.1581 g/cm³,孔隙率高达92.81%,比表面积为728.8225m²/g,平均孔径为5.2477 nm,形成了典型的三维纳米多孔网络结构。且在三甲基氯硅烷（TMCS）改性后,气凝胶接触角达到143.973°,表现出良好的疏水性能。采用汉麻秸秆芯提取的纤维素作为增强相,结合壳聚糖和甲基三甲氧基硅烷（MTMS）交联剂,制备了纤维素-二氧化硅复合气凝胶。该复合材料具有超轻特性,密度低且疏水性能优异,接触角最高可达130°。具备良好的力学性能,在86.65%应变下最大应力为55.056 KPa;经过100次压缩循环测试后,材料仍能保持75%的原始高度。此外,复合材料导热系数稳定在0.0465～0.0653 W/（m·K）之间,具有显著的隔热优势。在优化后的TEOS基气凝胶的基础上结合碳纤维毡材料,制备了SiO₂复合气凝胶毡材料。通过引入树脂熔融工艺,形成三维结构,解决了传统气凝胶毡掉粉掉渣的问题。研究表明,280℃、5-10 min的熔融条件可有效避免树脂碳化,同时增强气凝胶与碳纤维的物理结合。树脂含量为10%时,复合材料界面结合显著改善,热稳定性提高,有效解决了掉粉掉渣问题。本研究通过多尺度增强策略和工艺优化,显著提升了SiO₂气凝胶的力学性能和结构完整性,为其在隔热、减震等领域的实际应用提供了理论依据和技术支持。更多还原

【Abstract】 With the acceleration of industrialization and the increasingly severe energy crisis,the development of green and low-carbon thermal insulation materials holds significant importance for achieving energy-efficient utilization and sustainable development.However,current commercial thermal insulation materials exhibit inherent limitations.Consequently,developing novel,lightweight,stable,and highly efficient insulating materials could mitigate energy losses and facilitate the implementation of sustainable development strategies.Silica aerogel is a new type of thermal insulation material with unique properties such as low density,high specific surface area,high porosity,low thermal conductivity,and so on,which is composed of nanometer-level pore structure.However,the practical applications of silica aerogels are constrained by inherent limitations such as prolonged preparation periods and inferior mechanical properties.To address these challenges,this study implemented precise modulation of the chemical composition and network architecture of silica aerogels,coupled with a multiscale reinforcement strategy.Cellulose（microscale）and carbon fiber felt（macroscale）were strategically selected as reinforcing phases to construct a hierarchical reinforcement system.The influence laws of preparation parameters such as fiber content on the microstructure,mechanical properties and thermal properties of the composites were systematically investigated to solve the problem of fallout and slagging of silica aerogels and composites in practical applications.The specific research work is as follows:The preparation process of TEOS-derived Si O₂aerogels was optimized to achieve rapid fabrication under ambient temperature and pressure conditions.By precisely controlling the pH and temperature during the hydrolysis-condensation stages,along with the molar ratios of TEOS,EtOH,and H₂O,the conventional preparation cycle was significantly reduced from 5–7 days to 48 hours.The resulting Si O₂aerogels exhibited exceptional properties:an ultralow density of 0.1581 g/cm³,a high porosity of 92.81%,a specific surface area of 728.8225 m²/g,and an average pore diameter of 5.2477 nm,collectively forming a characteristic three-dimensional nanoporous network structure.Furthermore,after TMCS modification,the aerogel demonstrated a water contact angle of 143.973°,indicating robust hydrophobicity.Cellulose-silica composite aerogels were prepared by using cellulose extracted from hemp straw cores as the reinforcing phase,integrated with chitosan and MTMS crosslinkers.The composite exhibited ultralight characteristics with low density and superior hydrophobicity,achieving a maximum water contact angle of 130°.It demonstrated robust mechanical properties,including a maximum stress of 55.056k Pa at 86.65%strain,and retained 75%of its original height after 100 compressive cycles.Furthermore,the composite maintained a stable thermal conductivity ranging from 0.046469 to 0.06534 W/（m·K）,highlighting its remarkable thermal insulation advantages.Building upon the optimized TEOS-derived silica aerogel,a Si O₂composite aerogel felt was fabricated by integrating carbon fiber felt.By introducing the resin melting process to form a three-dimensional structure,the problem of powder and slag falling from traditional aerogel mats was solved.It was shown that the melting conditions of 280℃and 5-10 min could effectively avoid the carbonization of the resin,and at the same time enhance the physical bonding between the aerogel and the carbon fiber.When the resin content is 10%,the interfacial bonding of the composite material is significantly improved,the thermal stability is improved,and the problem of powder and slagging is effectively solved.In this study,the mechanical properties and structural integrity of Si O₂aerogels were significantly enhanced through multi-scale enhancement strategies and process optimization,which provided theoretical basis and technical support for their practical applications in the fields of heat insulation and vibration damping.更多还原