title: Development of high-porosity resorcinol formaldehyde aerogels with enhanced mechanical properties through improved particle necking under CO2supercritical conditions.
abstract: A new high porosity resorcinol-formaldehyde (RF) aerogel with improved particle necking is presented in this work. This RF aerogel was developed under CO2supercritical 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 0.0249W/mK were obtained.
authors.affiliation: Microcellular Plastic Manufacturing Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario M5S 3G8, Canada.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Alshrah
authors.affiliation: Microcellular Plastic Manufacturing Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario M5S 3G8, Canada.
authors.forename: Minh-Phuong
authors.initials: MP
authors.lastname: Tran
authors.affiliation: Microcellular Plastic Manufacturing Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario M5S 3G8, Canada.
authors.forename: Pengjian
authors.initials: P
authors.lastname: Gong
authors.affiliation: Smart and Adaptive Polymers & Composites Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario M5S 3G8, Canada.
authors.forename: Hani E
authors.initials: HE
authors.lastname: Naguib
authors.affiliation: Microcellular Plastic Manufacturing Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario M5S 3G8, Canada. Electronic address: park@mie.utoronto.ca.
authors.forename: Chul B
authors.initials: CB
authors.lastname: Park
keywords: Aerogel; Gelation; Heat transfer; Nanomaterials