Structure and properties of thermoplastic/thermoset-blended phenolic fibers

Thermoplastic high-ortho phenolic resins (HOP-PRs) were blended with thermosetting high-ortho phenolic resins (HOT-PRs), and the resulting blended modified phenolic as-spun fibers (AFs) were obtained through wet spinning. The blended modified phenolic fibers (o-BPFs) were prepared using various curing methods, including solution thermal curing (STC) and microwave thermal curing (MTC). The characterization was performed using such techniques as infrared spectroscopy, nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), fibers strength testing, and scanning electron microscopy. The results showed that the blend modification by introducing HOP-PRs improved the spinnability of the fibers. With the assistance of microwaves, +CH2OH also reacted more fully with the phenolic rings inside the fibers, while the cross-linking degree of the fibers was also improved by heat treatment. Therefore, the MTC fibers showed the best mechanical properties with an elongation of 3.3% and a tensile strength of 124.4 MPa.