An initial weight loss was observed for all cellulosic samples in the region below 100 °C, mainly corresponding to the evaporation of moisture content or any other volatile low-molecular-weight compounds loosely bound to the surface or inside the materials . The presence of absorbed water was also observed by FTIR characteristic peaks at the signal of 1640 cm−1, which represents the bending vibration of intermolecular hydrogen bonding of water molecules. The DTG curve revealed there is a major difference in the decomposition temperature between native cellulose and CNCH2SO4, in which the CNCH2SO4 started to undergo a degradation process much earlier (at 210 °C) than that of cellulose as well as CNCCr(NO3)3. This phenomenon was accredited to several possible reasons: (i)The replacement of hydroxyl groups (O–H) by active sulfate groups (O–SO3H) via either esterification or direct catalysis would initiate the dehydration reaction to occur on the sulfated nanocellulose fiber, leading to the water formation, further catalyzing the decomposition of remaining cellulose fiber into smaller particles. On the other hand, the unsulfated crystals tend to collapse at higher decomposition temperature ;(ii)It was believed that the concentrated H2SO4 not only removes the loosely-packed defective parts but also has high potential to damage crystalline domains, making the molecules more susceptible to the degradation step in response to increased temperature ;(iii)The rapid reduction of molecular weight of nanocellulose during hydrolysis compared to that of its starting material contributed to its early decomposition during heating treatment ;(iv)The short nanocellulose chains provide a high specific surface area and result in the formation of a large number of free-end-chains in the surface that tended to decompose easily at a lower temperature. The high surface area of nanocellulose plays a significant role in diminishing their thermal stability due to the increased exposure to heat source .