The morphology and mechanical properties of layer structured cellulose microfibril foams from ice-templating methods
Ice-templated (IT) cellulose microfibril porous foams with unique layer structure and controllable channels were successfully fabricated via unidirectional freezing methods. The cellulose microfibril foam prepared from 1.0 wt% suspension shows a cross-linked network structure. Increasing the content of the cellulose microfibril in the suspension up to 2.75 wt% led to a gradual transition from a crosslinked network structure to a lamellar channel structure. Increasing the concentration of microfibrils in the suspension up to 8.0 wt% caused an increase of the thickness of wall and bridge degree. The wavelength of IT channel structures could be controlled from 2.8 μm to 11.2 μm by changing the temperature gradient between the ice front and the cellulose microfibril suspension. The compressive stress of IT cellulose microfibril foams increases linearly from 30.7 KPa to 360.2 KPa with increasing concentrations of cellulose microfibril suspension from 2.0 wt% up to 8.0 wt%.