Cellulose Nanofibers/Polycarbonate Nanocomposite

Abstract

In this study, cellulose nanofiber (CNF) was prepared from carrot residues and further surface modification was carried out using suspension polymerization. Subsequently, these CNFs were added to polycarbonate (PC) to prepare a series CNF reinforced nanocomposites. TEM results show that the average diameter of the fiber after 2,2,6,6-Tetramethylpiperidinyloxy (TEMPO) radical oxidation is 4.46 nm, and the average diameter of the TEMPO oxidized nanofiber modified by suspension polymerization is 7.65 nm, which confirms that the carrot fiber has been successfully prepared into nanoscale. The results of FT-IR analysis show that the lignin and impurities on carrot fibers can be removed effectively after alkali treatment. In addition, the absorption peak of the functional group analyzed by FT-IR also confirmed that the TEMPO radical oxidation and suspension polymerization method were successfully carried out. Contact angle analysis results show that the contact angle of the CNF modified by suspension polymerization method was increased, indicating that the hydrophobicity of the fiber has been significantly improved. Moreover, this will lead to the better compatibility between CNF and PC matrix. Mechanical property analysis also shows that the surface modified CNF has a stronger reinforcing effect on PC than the unmodified one. Furthermore, the results show that the dispersion of CNF in the matrix of nanocomposite prepared by dilution of masterbatch was better than that of the one prepared by directly adding of CNFs. The better dispersion of CNFs in the PC matrix led to the better mechanical properties. The increment of tensile strength of the nanocomposite prepared by dilution of masterbatch can reach to 21.75%. In the analysis of transparency, the transmittance of modified CNF containing nanocomposite was larger than that of unmodified CNF containing one. The transmittance of the nanocomposites containing modified CNFs was larger than 70%, which was close to that of pure PC.