Handbook of Thermosetting Foams, Aerogels, and Hydrogels: From Fundamentals to Advanced Applications

Abstract

The development of phenolic resins that invigorated the polymer industry is considered to be the first synthetic resin developed and thus, leaves an indelible mark in the field of polymer science. These thermoset resins are synthesized by the condensation polymerization of phenol or a mixture of phenols along with an aldehyde. Among the various phenolic products, phenolic foams (PFs) are unique and versatile materials that have a wide variety of applications ranging from thermal insulation to marine applications. Because of its versatility and range of applications, PFs have huge research significance by virtue of its high thermal stability and flame resistance, low thermal conductivity combined with the lower generation of toxic gases during decomposition. PFs bearing a combination of excellent properties such as thermal and electrical insulation, light weight, energy absorption, and fire protection that made them an attractive engineering materials for a number of high-end technological and engineering applications. Although PFs exhibits excellent fire-retardant and thermal insulation properties, they suffer from insufficient mechanical properties (e.g., fatigue, flexural properties, and friability) for a range of engineering applications, compared to other thermosetting foam materials. The properties of PFs can easily tuned by controlled cross-linking, composite with different fillers, and their dosage. Cell density and cell size changes play a vital role in the overall enhancement of the strength and compressive properties of the PFs. In addition to this, a numerous approaches have been tried to enhance the mechanical properties of the PFs without deteriorating its excellent fire-retardant and electrically insulating properties. Incorporation of fibers and particulate fillers or the chemical modification of the PF resin also adopted to improve their mechanical properties; however these approaches showed certain limitation. A novel strategy adopted is reinforced the PF by incorporating nanostructured materials including nanosized metallic oxides, carbon nanomaterials, nanocellulose, and nanoclay. This reinforcement has been reported to improve the compressive, flexural, and impact strength of the PFs. The chapter comprehensively review and analyzes the PFs reinforced with various nanomaterials, their basic chemistry and technology, preparation, processing, and areas of their applications. © 2024 Elsevier Inc. All rights reserved.