Drying cellulose nanocrystal suspensions
Publication Name: Production and Applications of Cellulose Nanomaterials
Publication URL: https://www.fpl.fs.usda.gov/documnts/pdf2013/fpl_2013_peng003.pdf
Drying cellulose nanocrystals (CNCs) while maintaining their nanoscale dimensions is a major chal- lenge for uses which require a dry form of the material. Three methods were examined here to dry CNC suspen- sions: (1) air drying, (2) freeze drying (FD), and (3) spray-drying (SD). The effect of drying methods on the morphology, thermostability, and surface energy of CNCs was evaluated using scanning electron microscopy, ther- mogravimetric analysis, and inverse gas chromatogra- phy. Air-drying formed solidly packed CNCs. FD formed ribbon-like structures of CNCs with nanoscale thickness- es. SD formed particles with a size distribution ranging from nanometers to several microns. Freeze-dried CNCs had a lower dispersion component of surface energy than air-dried and spray-dried CNCs. The drying methods do not significantly affect the onset temperatures of thermal degradation of CNCs. Spray-drying is proposed as a technically suitable manufacturing process to dry CNC suspensions.