Surface modification of cellulosic nanofibrils by spray drying: Drying yield and microstructural, thermal and chemical characterization

This study investigated the effect of the addition of cationic surfactant cetyltrimethylammonium bromide (CTAB) in cellulose nanofibril suspensions (CNF) on the efficiency of the spray drying process, as well as on the properties of the dried microparticles and on their water redispersibility. The results indicated that CNF pretreated with 10% sodium silicate and modified with surfactant resulted in higher drying yields. The particle sizes formed by drying depended on the characteristics of the precursor CNF, in general, the particles were smaller than 8 µm. The crystalline fraction of all particles produced was higher than that of never dried (ND) CNF, furthermore the powders were thermostable at elevated temperatures (>200 °C), which provides good evidence for applications in composites. Water stability showed that the rehydrated cellulose solutions were influenced by the treatments and the drying process. The addition of surfactant proves attractive to increase the spray drying yield of CNF, bringing prospects regarding cost reduction and expansion of CNF commercialization. Furthermore, the results provide fundamental insights into the relationship between the surface modification of CNF associated with the drying process with the characteristics of the spray-dried material.