Nondestructive and noncontact evaluation of cellulose nanofiber-reinforced composites using terahertz time-domain spectroscopy

Cellulose nanofibers (CNFs) can be obtained from natural sources, such as plants and wood fibers. Thermoplastic resin composites reinforced with CNFs exhibit various features, including superior mechanical strength. As the mechanical properties of composites reinforced with CNFs are affected by the amount of fiber addition, it is important to determine the concentration of the CNF filler in the matrix after injection or extrusion molding. We confirmed that there was good linearity between the CNF concentration and terahertz absorption. We could distinguish the difference in the 1%-point-CNF concentration with terahertz time-domain spectroscopy. Furthermore, we estimated the mechanical properties of the CNF nanocomposites using terahertz information.