Pinilla-Peñalver Esther, Cantero Darío, Romero Amaya, Sánchez-Silva Luz
Department of Chemical Engineering, University of Castilla-La Mancha, Avda. Camilo José Cela 12, 13071 Ciudad Real, Spain.
Gels. 2024 Mar 20;10(3):209. doi: 10.3390/gels10030209.
This research presents a novel approach to synthesising polyurethane (PUR)-based aerogels at the pilot scale, optimizing synthesis variables such as the gelation solvent, solids content, chain extender/isocyanate ratio, and dispersion mode. The solids content (2-11 wt.%) is the parameter with the most influence on the density of the aerogels, with a clear decrease in this property as the solids content decreases. On the other hand, it was demonstrated that minimizing the excess of ethylenediamine (used as chain extender) in relation to the isocyanate is a valuable consideration to improve the thermal conductivity of the aerogel. Related to the chain extender/isocyanate ratio, a compromise situation where the initial isocyanate reacts almost completely is crucial. Fourier-transform infrared spectroscopy was used to conduct such monitoring during the reaction. Once the conditions were optimised, the aerogel showing improved properties was synthesised using ethyl acetate as the gelling solvent, a 3.7 wt.% solids content, an ethylenediamine/isocyanate ratio of 0.20, and sonication as the dispersion mode, attaining a thermal conductivity of 0.030 W m K and a density of 0.046 g cm. Therefore, the synthesized aerogel emerges as a promising candidate for use in the construction and automotive industries.
本研究提出了一种在中试规模下合成聚氨酯（PUR）基气凝胶的新方法，优化了诸如凝胶化溶剂、固体含量、扩链剂/异氰酸酯比例和分散方式等合成变量。固体含量（2-11 wt.%）是对气凝胶密度影响最大的参数，随着固体含量的降低，该性能明显下降。另一方面，已证明相对于异氰酸酯，尽量减少乙二胺（用作扩链剂）的过量是提高气凝胶热导率的一个重要考虑因素。关于扩链剂/异氰酸酯比例，初始异氰酸酯几乎完全反应的折衷情况至关重要。在反应过程中使用傅里叶变换红外光谱进行此类监测。一旦条件优化后，使用乙酸乙酯作为凝胶化溶剂、3.7 wt.%的固体含量、乙二胺/异氰酸酯比例为0.20以及超声处理作为分散方式，合成了性能得到改善的气凝胶，其热导率为0.030 W m K，密度为0.046 g cm。因此，合成的气凝胶成为建筑和汽车行业应用的有前景的候选材料。
