Rheological premonitory of nanoclay morphology on the mechanical characteristics of composite aerogels

Abstract

Composite aerogels with polymers and nanofillers have been attracting heterogeneous attention recently. Various nanofillers, with different morphologies, are used for requiring properties. However, these fundamental relationship between the morphology and the resulting properties are still unclear. In this study, amylopectin is modified with cations to bind two types of nanoclay dispersions, i.e. (1) disk-like type (D type) of montmorillonite (MMT) and Laponite (Lap) and (2) rod-like type (R type) of sepiolite (Sep) and halloysite (Hal). The rheological behaviors of resulting hydrogels or sticky fluids are carefully investigated, and subsequently, related to the microstructure and mechanical properties of the aerogels. By comparing, D type nanoclays can gel with cationic amylopectin because of high surface area and charge density. In addition, more regular cell structure and higher compression strength of the aerogels are obtained with higher specific area and low viscosity of MMT dispersion. The aerogel samples, with simple infrastructure, are further proved with extremely high fire safety and promising as, for instance, building insulation.