Abstract We report on the relationship for structure, compression and thermal insulation properties of cellulose diacetate-based aerogels (CDBAs), prepared from cellulose diacetate (CDA) cross-linked with 2, 4-toluene diisocyanate (TDI) by using sol-gel and supercritical drying processes. Lower reactant dosage (no matter CDA or TDI), can induce smaller shrinkage (~12%) after supercritical drying, and even to achieve lower density (~0.06 g/cm3) of CDBAs. Monolith CDBAs have typical three-dimensional networks with lamella reinforced fiber-like skeletons and nanometric pores. Such reinforced networking structure with lamellas as reinforcement is responsible for the maximum compression strength of ~1.29 MPa at 10% strain and compressive modulus of 21.86 MPa in CDBAs. Besides, the excessive addition of TDI leads to accelerate the growth of secondary fiber-like skeletons to ultimately divide the large pores into the small ones inside the formed network. This structural evolution enables to synergistically reduce gaseous thermal conductivity by means of Knudsen effect and increase that of solid part due to wider solid contacted area. The minimum total thermal conductivity of ~0.0313 W m−1 K−1 at ambient environment is obtained when the synergetic effects reach up to the critical balance, whose solid and gaseous proportions are calculated as 51.76 and 48.24%, respectively.

中文翻译：

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基于二乙酸纤维素的气凝胶的结构、压缩和隔热性能

摘要 我们报告了二乙酸纤维素基气凝胶 (CDBA) 的结构、压缩和隔热性能的关系，该气凝胶由二乙酸纤维素 (CDA) 与 2, 4-甲苯二异氰酸酯 (TDI) 交联而成，使用溶胶-凝胶和超临界干燥工艺。较低的反应物用量（无论是 CDA 还是 TDI），在超临界干燥后可以引起较小的收缩（~12%），甚至可以实现更低的 CDBA 密度（~0.06 g/cm3）。整体式 CDBA 具有典型的三维网络，具有薄片增强的纤维状骨架和纳米孔。这种以薄片作为增强物的增强网络结构在 CDBA 中在 10% 应变和 21.86 MPa 的压缩模量下的最大压缩强度为~1.29 MPa。除了，过量添加TDI会加速二级纤维状骨架的生长，最终将形成的网络内部的大孔分成小孔。这种结构演变能够通过克努森效应协同降低气体热导率，并由于更宽的固体接触面积而增加固体部分的热导率。当协同效应达到临界平衡时，周围环境下的最小总热导率为~0.0313 W m-1 K-1，其固气比例分别计算为51.76和48.24%。这种结构演变能够通过克努森效应协同降低气体热导率，并由于更宽的固体接触面积而增加固体部分的热导率。当协同效应达到临界平衡时，周围环境下的最小总热导率为~0.0313 W m-1 K-1，其固气比例分别计算为51.76和48.24%。这种结构演变能够通过克努森效应协同降低气体热导率，并由于更宽的固体接触面积而增加固体部分的热导率。当协同效应达到临界平衡时，周围环境下的最小总热导率为~0.0313 W m-1 K-1，其固气比例分别计算为51.76和48.24%。