Thermal degradation behavior of cellulose nanofibers and nanowhiskers

The thermal degradation behavior of different types of cellulose before and after mechanical defibrillation and lyophilization was studied using isothermal and non-isothermal thermogravimetric analyses, followed by other characterization techniques, such as X-ray diffraction, Fourier transform infrared spectroscopy, degree of polymerization and scanning electron microscopy with field emission analysis. The thermogravimetric experiments were carried out in a nitrogen atmosphere at four different heating rates (5, 10, 20 and 40 degrees C min(-1)) in a non-isothermal condition. Distinct thermal degradation behaviors were observed when the two types of cellulose were compared after defibrillation: (1) cellulose nanofibers tend to lose thermal stability and (2) cellulose nanowhiskers tend to gain thermal stability. The Flynn-Wall-Ozawa method results indicate that the apparent activation energies calculated for the cellulose fiber sample has higher values requiring more energy for the thermal decomposition. Criado curves indicated a degradation mechanism for the cellulose: one-dimensional diffusion.