Comparative study of the structure, mechanical and thermomechanical properties of cellulose nanopapers with different thickness

This article describes the comparative study of the structure, mechanical and thermomechanical properties of cellulose nanopapers with different thicknesses. Cellulose nanopapers were fabricated by vacuum-filtering cellulose nanofiber (CNF) suspensions. The surfaces of the nanopapers consisted of long and entangled CNFs (10–30 nm in width) and their aggregates, while cross-sections exhibited parallel aligned lamellar structures. The nanopaper thickness can be tailored by controlling the amounts of CNF suspensions used for filtration. Owing to the packing density of CNFs, nanopapers with different thicknesses had similar densities of ~1.50 g cm⁻³. The thin nanopapers were transparent and flexible. With increasing thickness, the Young’s modulus of the nanopapers slightly decreased, while the ultimate strain and work of fracture increased. The thicker nanopapers displayed higher storage and loss modulus. The nanopapers still kept advantageous mechanical properties even at high temperatures around 260 °C because of the high thermal stability of CNFs and their strong entangled web-like structures.