Modified stabilization route for the preparation of HDPE-derived porous carbon fibers

• A three-step stabilization strategy yields uniformly crosslinked carbon fibers. • Electron beam irradiation, sulfonation, and phosphorylation are used • The fibers have improved crystallite order and balanced micro-and mesoporosities. • The strategy can help produce high-performance PCFs from thermoplastic precursors. Porous carbon fibers offer high specific surface area, rapid adsorption kinetics, and excellent structural durability, making them attractive for environmental and energy-related applications. However, converting polyolefin-based precursors such as high-density polyethylene into carbon fibers is challenging because severe structural collapse often occurs during carbonization. In this study, we propose a three-step stabilization strategy consisting of electron-beam irradiation, sulfonation, and phosphorylation, which enhances thermal stability and enables the formation of uniformly crosslinked fibers throughout the fiber cross section. Thermogravimetric analysis showed that the multi-acid stabilization produced a char yield comparable to that obtained by sulfuric-acid-only treatment (47.36% vs. 47.41% at 800℃). Tensile strength measurements after carbonization revealed that fibers treated with the multi-acid stabilization method exhibited approximately a 40% improvement compared to sulfonation-only fibers. Microstructural analyses using SEM, Raman spectroscopy, and XRD confirmed suppressed core collapse, reduced defect gradients, and improved crystallite ordering, which collectively facilitated enhanced mesopore development in the resulting porous carbon fibers.