| Abstract:To address the poor interfacial compatibility between polyimide (PI) fibers and wood pulp fibers (WF) caused by the inert surface of PI, this study proposed a three-step synergistic modification strategy involving alkali treatment, acid protonation, and silane coupling agent (KH-550) grafting, followed by wet-laid papermaking to fabricate PI&WF composite paper. The effects of alkali concentration, treatment time, treatment temperature, KH-550 dosage, and PI addition ratio on the composite paper properties were systematically investigated. The results showed that the optimal conditions were alkali concentration of 0.8 mol·L-1, treatment time of 40 min, treatment temperature of 70 °C, and KH-550 dosage of 4 wt%. Under these conditions, the tensile index, burst index, internal bonding strength, and density of the composite paper reached 25.89 N·m·g-1、2.57 kPa·m2·g-1、454.40 J·m-2和0.74 g·cm-3, respectively. Thermogravimetric analysis revealed that the introduction of 30% PI fibers increased the char residue from 20.19% to 31.51%, while the composite paper maintained structural integrity at 250 °C. This strategy provides a novel pathway for the fabrication of high-performance heat-resistant fiber paper. |