Optimisation of silica-cork aerogel composites for efficient fire-retardant thermoacoustic barrier

Abstract The development and optimisation of silica-cork aerogel composites, prepared with tetraethyl orthosilicate (TEOS) and vinyltrimethoxysilane (VTMS) as co-precursors and reinforced with short cut aramid fibres is herein presented. Different synthesis parameters, such as co-precursor ratio, amount of fibres, and cork granulate dimensions, were investigated using a design of experiments approach to obtain composites with lower bulk densities and thermal conductivities. The obtained materials presented densities ranged from 0.140 to 0.190 g cm −3 and thermal conductivities in the superinsulation range (16.6–19.1 mW m −1 K −1 ). These features, combined with their flexibility and thermal stability up to 300 °C, make the produced composites promising candidates for high-end applications in the automotive, buildings, and space industry, where high-performance insulation materials are needed. Also, the produced samples present sound absorption performance which expands their applicability to double barrier purpose, for heat and sound. Moreover, the composites exhibited excellent flame resistance after a qualitative test, even achieving flame extinction, positioning them as promising candidates for applications in the building industry. By utilizing renewable cork resources and improving energy efficiency, these materials can contribute to the reduction of environmental impact of insulator materials and will promote sustainable development in multiple sectors.