高强度、低导热的本征成炭杂化网络气凝胶泡沫的设计研究

Building thermal insulation are mainly realized by foam meterials. However, it’s very difficult for commercial organic foams to achieve the A-grade of flame retardancy. When using aerogel as foams, the obvious drawbacks of inorganic aerogels and the carbon aerogels, such as poor processability, expensive raw materials and complicated preparation, impede their applications. In this project, design of aerogels with novel hybrid network structure is proposed. A network formed by cationic amylopectin glued negatively charged nano particles is first constructed. And an additional network is formed by crosslinked water soluble polymer. Based on the mechanism of intumescent flame retardant (IFR), we fabricate these hybrid network aerogels with acid sources, carbon sources and blowing agents. Because of the high charring capability of IFR, the resulted aerogels are thus with excellent flame retardancy and smoke suppression. The hybrid network could remarkably enhance the framework and reduce the density and thermal conductivity. By adjusting the parameters of the ingredients, such as structures, morphologies or weight percentages, and controlling the ice-templated process, the microstructure of the hybrid network, which formed under the multi-interactions, will be further investigated. And the relationship between structure and performances will be established. Based on these results, aerogels with low thermal conductivity, high mechanical strength and inherent charring capability will be prepared. They also own the advantages of abundant material sources and facile, green fabricating processes. Furthermore, for their inherent charring property, the study on fire resistance mechanism will also reveal the regulation of the char, which may support the development of charring hybrid materials.

建筑保温主要用泡沫材料实现。商品化有机泡沫材料难以达到A级防火标准。而将气凝胶应用于泡沫材料时，无机气凝胶和碳气凝胶受到加工性差、原料昂贵和工艺繁琐等因素的制约。本项目提出了以阳离子改性支链淀粉胶黏负电纳米粒子制备交联网络、与进一步交联的水溶性高分子构筑新颖的杂化网络气凝胶。基于膨胀阻燃原理，杂化网络以碳源、酸源和气源成分进行构建，使之具有高效的阻燃、成炭和抑烟能力。通过杂化网络显著提升气凝胶的强度、降低其密度和导热。通过调节组分的结构、形貌和含量等参数、结合冰晶生长诱导-冷冻干燥过程，调控多相互作用力条件下形成的凝胶网络微结构，深入研究其构效关系，据此制备具有低密度、低导热率、高机械强度和高阻燃成炭能力的气凝胶材料。该材料所选原料来源广泛，制备过程温和绿色。基于材料的成炭剂本质，在研究其阻燃机理的同时可揭示炭层的调控机制，为广泛制备高效成炭复合材料提供理论和实践依据。

在我国，建筑单位面积能耗是气候相近的发达国家的3~5倍，建筑能耗高达社会总能耗的3~4成，既有建筑中超过80%为高能耗建筑。因此，走节能减排的可持续发展道路，减少建筑能耗是关键。然而，广泛采用的有机泡沫建筑保温材料非常易燃。在若干高层建筑重大火灾发生后，公安部消防局紧急提高了建筑用材的阻燃标准（公消[2011]65号文），在一段时期内，严格要求“民用建筑外保温材料采用燃烧性能为 A 级的材料”。.本项目的研究目标为，制备一系列不同分子结构的阳离子改性支链淀粉交联的负电荷纳米粒子凝胶网络，在此基础上以高效成炭体系为依据制备的杂化网络气凝胶。充分揭示多微观相互作用下导致的杂化网络气凝胶结构和性能上差异，以及配方变化条件下炭层结构的变化规律，在此基础上制备若干能达到GB8624-2012 A级阻燃标准的气凝胶泡沫材料。.本研究揭示了支链淀粉被阳离子改性以结合两种类型的纳米粘土分散体所得水凝胶或粘性流体的流变行为，并与气凝胶的微观结构和力学性能相关联。非常小比例阳离子化支链淀粉即可将纳米蒙脱土交联成紧密交联的三维网络，得到具有“水泥墙砖”特殊微结构的气凝胶，其机械强度、耐火性均达到预期目标。更进一步的，我们设计了聚乙烯醇/Laponite/粉煤灰杂化网络气凝胶，达到了轻质、高强和A级难燃标准。而聚乙烯醇-三聚氰胺-甲醛树脂杂化网络气凝胶，据我们所知，是当前相关性能最好的纯有机高分子气凝胶。.上述研究结果为建筑用高强、难燃的气凝胶的选择和设计指出了方向，为固体废弃物的高效利用提供了新的途径，若将上述气凝胶应用于建筑保温，在过火场合，能有效地保护墙体不倒塌，为人员疏散留出足够的时间。