Bio-based aerogels are sustainable and eco-friendly materials that have gained increasing attention. However, their development is hindered by complex technological processes and unsatisfactory mechanical properties. To obtain a multi-scale hierarchical micro-meso porous composite aerogel with extraordinary thermal insulation and mechanical properties via simple and facile preparation process, we used oxidized cotton linter fiber (CF) as the skeleton and reinforcement, oxidized microcrystalline cellulose (MCC) as the supporting and filling matrix, and PVA as the crosslinking agent and a good glue to enhance the interaction between CF and MCC, and the porous network of the composite aerogel. The composite aerogel is very light, strong, and flexible. The best obtained composite aerogel has a apparent density of only 67.5% of the pure cotton fiber composite aerogel (CF), a maximum compressive stress of 1.22 MPa, which is 22 times higher than the pure microcrystalline composite aerogel (MCC), and a thermal conductivity of 0.0335 W/m.K, which is 89% lower than CF. These properties make the composite aerogel suitable for various thermal insulation applications, such as protective clothing for extremely cold environment.

中文翻译：

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由棉花废料制成的坚固纤维素复合气凝胶，具有增强的隔热性和机械性能

生物基气凝胶是可持续且环保的材料，受到越来越多的关注。然而，其发展受到复杂的工艺流程和不令人满意的机械性能的阻碍。为了通过简单易行的制备工艺获得具有优异隔热性能和力学性能的多尺度分级微介孔复合气凝胶，我们以氧化棉短绒纤维（CF）为骨架和增强体，氧化微晶纤维素（MCC）为支撑和填充基体，PVA作为交联剂和良好的胶水，增强CF和MCC之间的相互作用，以及复合气凝胶的多孔网络。复合气凝胶非常轻、坚固且柔韧。获得的最佳复合气凝胶的表观密度仅为纯棉纤维复合气凝胶（CF）的67.5%，最大压应力为1.22 MPa，比纯微晶复合气凝胶（MCC）高22倍，热力学性能优异。电导率0.0335 W/mK，比CF低89%。这些特性使得复合气凝胶适用于各种隔热应用，例如极冷环境下的防护服。