Preparation and Properties of Epoxy-Modified Thermosetting High-ortho Phenolic Fibers

This study focused on thermosetting high-ortho phenolic epoxy fibers prepared by blending thermosetting high-ortho phenolic resins (HOT-PRs) with F-704 epoxy resins and using dry spinning, thermal curing, and microwave curing methods. The structure was characterized by infrared spectroscopy, microinfrared spectroscopy, nuclear magnetic resonance spectroscopy, and scanning electron microscopy. The heat resistance of different fibers was studied by thermogravimetric analysis, and the mechanical properties of the fibers were determined using a fiber tensile strength tester. Results showed that the HOT-PRs successfully used the phenolic hydroxyl groups and the hydroxyl groups in the methylol groups to promote the ring-opening reaction of the epoxy groups to form ether bonds. The breaking strength of the thermally cured fibers was 206 MPa, and the elongation at break was 14.5%. The microwave-cured fibers had good heat resistance with an initial weight loss temperature of 315°C and a char yield of 59.7% at 800°C.