Effect of lignin on the thermal stability of cellulose nanofibrils produced from bagasse pulp

Abstract

In this work, the effects of lignin on the thermal stability of bagasse cellulose nanofibrils (CNFs) were investigated. The CNFs were prepared with different lignin content bagasse pulp using ultrafine grinding combined with high-pressure homogenization. Scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and thermogravimetric analysis were used to study the influence mechanisms of lignin content on the thermal stability of the CNFs. The thermal stability of cellulose was tested by thermogravimetric analyzer at different heating rates, and the activation energy of bagasse cellulose nanofibrils was calculated by Flynn-Wall-Ozawa method. The results showed that the average width of CNFs prepared by the mechanical method was approximately 20 nm. The higher the lignin contents in the CNFs, the lower the crystallinity and the better the thermal stability. The thermal decomposition activation energy of CNF fluctuates with the change of conversion rate. Under the same conversion rate, the higher the lignin contents in the CNFs, the larger the activation energy value. The average activation energies of NO-LCNF, L-LCNF, ML-LCNF, MH-LCNF, and H-LCNF were 208.14, 254.49, 412.95, 530.54 and 652.10 kJ/mol, respectively, during the conversion rate of 20% to 90%. The research results provide a theoretical basis for the pyrolysis mechanism and high value utilization of CNFs and have a profound impact on promoting the application and development of CNFs in emerging nanocomposites.