Development of high-porosity resorcinol formaldehyde aerogels with enhanced mechanical properties through improved particle necking under CO₂ supercritical conditions

详细信息    查看全文

• 作者：Mohammed Alshrah^a ; Minh-Phuong Tran^a ; Pengjian Gong^a ; Hani E. Naguib^b ; Chul B. Park^a ; ^{park@mie.utoronto.ca" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Aerogel ; Gelation ; Heat transfer ; Nanomaterials
• 刊名：Journal of Colloid and Interface Science
• 出版年：2017
• 出版时间：1 January 2017
• 年：2017
• 卷：485
• 期：Complete
• 页码：65-74
• 全文大小：3253 K

文摘

A new high porosity resorcinol-formaldehyde (RF) aerogel with improved particle necking is presented in this work. This RF aerogel was developed under CO₂ supercritical drying conditions without any structural shrinkage. The water content and the catalyst percentage were varied to modify the particles’ nucleation and growth mechanisms and to control particle-particle connections. The nucleation mechanism solely dependent on the initial catalyst percentage; the number of nuclei increased with the catalyst percentage. However, the growth and connection of the particles dependent on both the water content and the catalyst percentage through their effect on the pH value. As the water content increased to have a larger void fraction, the pH value decreased. Consequently, the spherical growth of the particles became dominant and, thereby, the connection of the particles became more difficult. But as the catalyst percentage increased, the pH value increased, and the connection of the particles became facilitated with the formation of necks around the particles. As a result, the semi-fibril-like structure was developed with a high void fraction. A 30% increase in the structural elasticity and a very low thermal conductivity of 0.0249 W/mK were obtained.