CHANGES IN SOLID-STATE CELLULOSE NANOFIBERS INDUCED BY GAMMA-RAY IRRADIATION: COMPARATIVE EVALUATION OF PURE AND LIGNIN/HEMICELLULOSE-CONTAINING STRUCTURES

In this study, the effects of gamma-ray irradiation on the physicochemical properties of cellulose nanofiber (CNF) and lignin/hemicellulose-containing cellulose nanofiber (LHCNF) were investigated. Solid-state CNF (SS-CNF) and solid state LHCNF (SS-LHCNF) sheets were prepared and irradiated with gamma-rays at doses of 60 and 300 kGy. Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) analyses revealed no significant changes in the chemical structure or crystallinity. These results suggest that the chemical changes (damage) are minor and cannot be confirmed by the available instruments. Tensile testing showed a dose-dependent decrease in the maximum stress for both types of CNF sheets, indicating radiation-induced damage. However, while the elastic modulus of SS-CNF decreased with increasing irradiation dose, SS-LHCNF retained approximately 90% of its modulus, even after 300 kGy, demonstrating higher mechanical stability. Thermogravimetric analysis further revealed that the 1% weight-loss temperature decreased monotonically with irradiation dose for SS-CNF, whereas SS-LHCNF showed only a moderate decrease between 60 and 300 kGy. These results highlight that the presence of lignin and hemicelluloses (and their derivatives) in LHCNF influences the extent of changes in physicochemical properties induced by gamma-ray irradiation.