Focusing on lignin flowability of bamboo fibers extracted from machining centers a study of optimum molding conditions for self-adhesive molded bamboo fibers

Abstract

In this study, we are attempting to create self-adhesive moldings made entirely from bamboo fibers extracted by a machining center in order to solve global environmental problems and the destruction of ecosystems caused by bamboo. However, the mechanical properties of the moldings are still insufficient. In the present report, we clarify the molding conditions that can improve the mechanical properties of the molded plates. First, the cause of fracture of the plates during tensile testing was investigated. As a result, it was considered that the cause was the fracture at the adhesion area or fiber withdrawal. To enhance the adhesive action, we focused on lignin, an adhesive component in bamboo, and its flow process during molding. We investigated the effects of in-mold temperature and pressure and molding time on the thermal flow of lignin. As a result, it was found that the thermal flow of lignin progressed and the mechanical properties improved as the time and pressure were increased. Therefore, we attempted to determine the molding conditions that maximize the tensile strength of the moldings by referring to a manufacturing process model for fiber-reinforced composites. Five specimens were fabricated, and a tensile strength of 32.37 MPa was achieved with a standard deviation of 0.55 MPa, which is equivalent to that of general-purpose plastics.