木质纳米纤维素基材料热传导性能研究进展

木质纳米纤维素基材料，如气凝胶或泡沫，具有原料广泛、生物可降解且多孔性等特征。作为常温常压下使用的非导体材料，其热传导主要取决于气体传导，其次为固体传导，而对流和辐射换热则可忽略不计。研究者致力于通过筛选干燥方式（如超临界干燥、冷冻干燥、气干或者烘干）、优化干燥工艺参数、添加纳米填料以及疏水改性来调控材料的孔径以及超微结构，进而获得热导率低于空气热导率，室温下为25 mW/（m·K）的超级保温材料。这类材料有望替代市场上常见的建筑或包装用石油基保温材料，可极大地减少环境污染压力。文中概述木质纳米纤维素基材料的热传递过程，讨论木质纳米纤维素基材料的热传导及其影响因子和作用机制，期望对开发新型的、具有低热导率的超级保温材料提供参考。

Heat Transfer Property of Ligno-Nanocellulose-based Materials: A Review

Ligno-nanocellulose-based materials, such as aerogels or foams, have the characteristics of plenty source, biodegradability and porosity. The gas conduction contribution is the dominating contribution to the thermal conductivity of nonconductive materials at ambient conditions, followed by solid conduction, while the convection and radiation contribution are usually negligible under the same conditions. To obtain super-insulating materials, i.e., materials with thermal conductivity significantly lower than the value for air (25 mW/m·K at room temperature), many researches have attempted to control the pore size and ultra-microstructure of materials, including screening drying methods (e.g., supercritically dried, freeze-dried, ambient-dried and oven-dried methods), drying process parameters optimization, adding nano-fillers and hydrophobic modification. Super-insulating material is expected to replace common petroleum-based insulation materials for construction or packaging available on the market and thus can greatly reduce the environmental pollution. The paper summarizes the heat transfer process of ligno-nanocellulose-based materials and discusses the thermal conduction and its factors and acting mechanism. It is expected that this review will play an important role in the development of new super-insulation materials with low thermal conductivity.