Physical and bio-composite properties of nanocrystalline cellulose from wood, cotton linters, cattail, and red algae

Nanocrystalline celluloses (NCCs) were isolated from different cellulose sources such as wood (softwood and hardwood), non-wood plant (cotton linters and cattail), and marine pulp (red algae) by acid hydrolysis. The NCCs were compared with respect to their dimensions, shapes, degrees of polymerization, crystallinities, thermal stabilities, and effects on the properties of bio-composites. Self-assembly phenomena of the NCCs were observed by electron microscopy. The NCCs from red algae fibers had the longest length (~432 nm) and the highest aspect ratio among the five cellulose sources. The NCCs from cotton linters, cattail fibers, and red algae fibers showed greater thermal degradation resistance than those from wood fibers. The NCCs with much lower molecular weights than their starting materials showed much higher crystalline indices than their starting ones. All-cellulose bio-composites, where the prepared NCCs were used as filaments and the dissolved cellulose as matrix, displayed increased Young’s moduli in proportion to the added amount of the NCCs.