5.2.3 Cellulose Nanocrystals5.2.3.1 Acid HydrolysisCNC have been traditionally produced by acid hydrolysis, where disordered or para-crystalline regions are first solubilized, leaving behind the crystalline domains or CNC, which possess a higher resistance to acid [190]. Although both sulfuric and hydrochloric acids have been the most used for this purpose, other acids, like phosphoric or hydrobromic acids, can be used. However, the dispersability of CNC produced from these acids is different. Due to the abundance of charged sulfate or phosphate groups on its surface, CNC obtained from sulfuric or phosphoricacid hydrolysis dispersed readily in water, while those produced from hydrochloric or hydrobromic acid hydrolysis are not as easy to disperse since their aqueous suspensionstend to flocculate. In addition, differences in the thermal stability and rheological behavior between the CNC produced from sulfuric acid and those from hydrochloric acid were observed [6].