Preparation and compressive properties of polyimide/silica composite fibers via a vapor deposition method

Abstract To address the issues of the surface inertness and poor compression resistance of polyimide (PI) fibers, a series of PI/SiO₂ composite fibers were prepared by using a vapor deposition method to deposit an SiO₂ shell on the surface. The laws governing the evolution of the chemical structure and thickness of the SiO₂ shell over the vapor deposition time were investigated, and the effects of the properties of the shell layer on the surface contact angle, surface energy, interfacial shear strength (IFSS), mechanical properties of the monofilament, and compressive performance of the composites were explored. The results indicated that a uniform SiO₂ shell can be constructed on the PI fiber surface by the vapor deposition method. In comparison to the Origin, the surface energy and IFSS of the PI/SiO₂ composite fibers exhibited remarkable increases of 51% and 39%, respectively. The compressive strength of both monofilament and multifilament composites showed significant increases, rising from 350.8 to 613.5 MPa and from 268.5 to 345.8 MPa, respectively. The study presents a novel technical approach for the surface inorganic modification of high‐performance fibers and offers a fresh solution for improving the interface and compressive properties of organic fibers and their composites. Highlights A dense SiO₂ shell‐coated polyimide fiber was prepared by vapor deposition. Shell thickness was modulated by controlling the deposition time. The surface energy of the fiber was increased by approximately 51%. The compressive strength of polyimide fiber was enhanced by nearly 75%. The SiO₂ shell improved the interfacial properties of the fibers.