Functionalisation of clay aerogel composites for applications in construction

Abstract

Clay aerogels are relatively a new class of materials with number of merits suitable for many applications in various industrial sectors. With the current mandate to utilise environmentally friendly materials to produce functional materials, clay aerogels provide an attractive potential green solution to overcome thermal issues in construction. However for it to be effectively used as an insulation material, research work is required to address several critical issues and setbacks: the first of these is poor mechanical properties highlighted in the literature as its main weakness; the second is there extremely high hydrophilic and hygroscopic nature identified as the main research gap, which not only can cause a significant increase in thermal conductivity but also can disintegrate the aerogels. This thesis investigates and develops novel methodologies to overcome the associated setbacks through comprehensive characterisation and better understanding of mechanisms of formulation, architecture, behaviour and corresponding performance of clay aerogel constituents and composites: (I) The anisotropic structure of the aerogel was thoroughly investigated and its influence on properties was established; (II) By adjusting and tuning the mixing temperatures, the compressive modulus was enhanced by more than 7 folds; (III) Ultrasonic technologies were used to prepare organoclay- polyvinyl alcohol aerogel composites with 40% less moisture absorption in addition to lower thermal conductivity; (IV) Implementing organosilanes and isocyanates to prepare clay-PVA aerogels resulted in an effective method to reduce the moisture absorption by more than 40% with a 6 fold increase in compressive modulus; (VI) soluble water repellent was incorporated to prepare hydrophobic aerogel composites with contact angles of 140°; and (VII) Organosilanes and isocyanates are combined with a water repellent to generate highly functional clay aerogel composites. Overall this thesis paves the way for the industrialisation of functional clay-aerogel insulation materials for construction and other sectors.