Merillas Beatriz, Lamy-Mendes Alyne, Villafañe Fernando, Durães Luisa, Rodríguez-Pérez Miguel Ángel
Cellular Materials Laboratory (CellMat), Condensed Matter Physics Department, Faculty of Science, University of Valladolid, Paseo de Belén 7, 47011 Valladolid, Spain.
CIEPQPF, Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima, 3030-790 Coimbra, Portugal.
Gels. 2022 Jun 21;8(7):392. doi: 10.3390/gels8070392.
In this work, silica aerogel composites reinforced with reticulated polyurethane (PU) foams have been manufactured having densities in the range from 117 to 266 kg/m and porosities between 85.7 and 92.3%. Two different drying processes were employed (ambient pressure drying and supercritical drying) and a surface modification step was applied to some of the silica formulations. These composites, together with the reference PU foam and the monolithic silica aerogels, were fully characterized in terms of their textural properties, mechanical properties and thermal conductivities. The surface modification with hexamethyldisilazane (HMDZ) proved to improve the cohesion between the reticulated foam and the silica aerogels, giving rise to a continuous network of aerogel reinforced by a polyurethane porous structure. The samples dried under supercritical conditions showed the best interaction between matrixes as well as mechanical and insulating properties. These samples present better mechanical properties than the monolithic aerogels having a higher elastic modulus (from 130 to 450 kPa), a really exceptional flexibility and resilience, and the capacity of being deformed without breaking. Moreover, these silica aerogel-polyurethane foam (Sil-PU) composites showed an excellent insulating capacity, reaching thermal conductivities as low as 14 mW/(m·K).
在这项工作中，制备了用网状聚氨酯（PU）泡沫增强的二氧化硅气凝胶复合材料，其密度范围为117至266 kg/m³，孔隙率在85.7%至92.3%之间。采用了两种不同的干燥工艺（常压干燥和超临界干燥），并对一些二氧化硅配方进行了表面改性步骤。这些复合材料，连同参考PU泡沫和整体式二氧化硅气凝胶，在其结构性质、机械性能和热导率方面进行了全面表征。用六甲基二硅氮烷（HMDZ）进行的表面改性证明改善了网状泡沫与二氧化硅气凝胶之间的内聚力，形成了由聚氨酯多孔结构增强的连续气凝胶网络。在超临界条件下干燥的样品在基体之间表现出最佳的相互作用以及机械和绝缘性能。这些样品比整体式气凝胶具有更好的机械性能，具有更高的弹性模量（从130到450 kPa）、非常出色的柔韧性和弹性，以及能够在不破裂的情况下变形。此外，这些二氧化硅气凝胶-聚氨酯泡沫（Sil-PU）复合材料表现出优异的绝缘能力，热导率低至14 mW/(m·K)。
