PDF(Pubmed)
Abstract：
Thermally stable high-performance phenolic resin aerogels (PRAs) are of great interest for thermal insulation because of their light weight, fire retardancy and low thermal conductivity. However, the drawbacks of PRA synthesis, such as long processing time, inherent brittleness and significant shrinkage during drying, greatly restrict their wide applications. In this work, PRAs were synthesized at ambient pressure through a near-net shape manufacturing technique, where boron-containing thermosetting phenolic resin (BPR) was introduced into the conventional linear phenolic resin (LPR) to improve the pore characteristics, mechanical properties and thermal performances. Compared with the traditional LPR-synthesized aerogel, the processing time and the linear shrinkage rate during the drying of the PRAs could be significantly reduced, which was attributed to the enhanced rigidity and the unique bimodal pore size distribution. Furthermore, no catastrophic failure and almost no mechanical degradation were observed on the PRAs, even with a compressive strain of up to 60% at temperatures ranging from 25 to 200 °C, indicating low brittleness and excellent thermo-mechanical stability. The PRAs also showed outstanding fire retardancy. On the other hand, the PRAs with a density of 0.194 g/cm3 possessed a high Young\'s modulus of 12.85 MPa and a low thermal conductivity of 0.038 W/(m·K).
摘要：
热稳定的高性能酚醛树脂气凝胶（PRAs）由于重量轻，对隔热具有极大的兴趣，阻燃性和低导热性。然而,PRA合成的缺点，如处理时间长，干燥过程中固有的脆性和显著的收缩，极大地限制了其广泛应用。在这项工作中,PRAs是通过近净形状制造技术在环境压力下合成的，其中含硼热固性酚醛树脂（BPR）被引入到传统的线性酚醛树脂（LPR），以改善孔特性，力学性能和热性能。与传统的LPR合成气凝胶相比,可以显着减少PRAs干燥过程中的处理时间和线性收缩率，这归因于增强的刚性和独特的双峰孔径分布。此外，在PRAs上没有观察到灾难性故障和几乎没有机械退化，即使在25至200°C的温度下具有高达60％的压缩应变，表明低脆性和优异的热机械稳定性。PRAs还显示出优异的阻燃性。另一方面,密度为0.194g/cm3的PRAs具有12.85MPa的高杨氏模量和0.038W/（m·K）的低热导率。
