Manufacture of antibacterial carbon fiber-reinforced plastics (CFRP) using imine-based epoxy vitrimer for medical application.

An antibacterial carbon fiber-reinforced plastics (CFRP) was manufactured based on a vitrimer containing imine groups. A liquid curing agent was prepared to include an imine group in the matrix, and was synthesized without a simple mixing reaction and any purification process. The vitrimer used as the matrix for CFRP was prepared by reacting a commercial epoxy with a synthesized curing agent. The structural and thermal properties of the vitrimer were determined by Fourier transform-infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). In addition, the temperature-dependent behavior of the vitrimer was characterized by stress relaxation, reshaping, and shape memory experiments. The mechanical properties of composites fabricated using vitrimer were fully analyzed by tensile, flexural, short-beam strength, and Izod impact tests and had mechanical properties similar to reference material. Moreover, both the vitrimer and the vitrimer composites showed excellent antibacterial activity against Staphylococcus aureus and Escherichia coil due to the imine group inside the vitrimer. Therefore, vitrimer composites have potential for applications requiring antimicrobial properties, such as medical devices.

Investigation of Ib-Values for Determining Fracture Modes in Fiber-Reinforced Composite Materials by Acoustic Emission.

This study analyzed failure behavior using Ib-values obtained from acoustic emission (AE) signals. Carbon fiber/epoxy specimens were fabricated and tested under tensile loads, during which AE signals were collected. The dominant peak frequency exhibited a specific range according to fracture mode, depending on the fiber structures. Cross-ply specimens, with all fracture modes, were used and analyzed using b- and Ib-values. The b-values decreased over the specimens' entire lifetime. In contrast, the Ib-values decreased to 60% of the lifetime, and then increased because of the different fracture behaviors of matrix cracking and fiber fracture, demonstrating the usefulness of Ib-values over b-values. Finally, it was confirmed that abnormal conditions could be analyzed more quickly using failure modes classified by Ib-values, rather than using full AE data.