Thermal degradation behavior of cellulose nanofibers and nanowhiskers

Abstract

The thermal degradation behavior of different types of cellulose before and after mechanical defibrillation and lyophilization was studied using isothermal and nonisothermal 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°C min -1 ) in a nonisothermal 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.

Nanocomposite Film Based on Cellulose Acetate and Lignin-Rich Rice Straw Nanofibers

“…Thermal degradation of CA involves degradation of the cellulose backbone by decomposition of glycosidic linkages, depolymerization, dehydration, and the loss of acetate groups [ 42 ]. RSNF contains amorphous polymers—e.g., hemicellulose and lignin—in addition to the partially crystalline cellulose polymer, which has higher thermal stability than lignin and hemicelluloses [ 43 ]. As shown in the figure, CA shows the onset of degradation at a temperature of about 310 °C, while CA containing 2.5% and 10% RSNF showed an onset of degradation temperatures at about 291 and 285 °C, respectively.…”

Thermal and mechanical properties of chitosan nanocomposites with cellulose modified in ionic liquids

“…It is widely accepted that small particles with large number of free-end chains present in the sample induce decomposition at lower temperature [51,52]. According to that theory, TG results obtained for CHT/5 C II sample should be better than for CHT/5 CNC II.…”

Transparent lignin-containing wood nanofiber films with UV-blocking, oxygen barrier, and anti-microbial properties

“…The second step might also be the degradation point for the low crystalline parts of cellulose 96 generated during the CWNF production. The third degradation step could be the degradation point of the individualized cellulose nano-bers, 97 which were observed in TEM images. It is possible that the nal degradation step in the breakdown of lignin requires a higher temperature due to the formation of a protective char layer around the lignin particles, decreasing the heat transfer.…”