Influences of different imidization conditions on polyimide fiber properties and structure

Abstract In the present work we prepared co‐polyimide (PI) fibers with excellent mechanical and dielectric properties by the wet‐spinning method. The co‐PI fiber exhibited high mechanical property with a tensile strength of 2.61 GPa and modulus of 86.7 Gpa as well as a low dielectric constant and a dielectric loss factor of 2.7463 and 0.00793 at 10 GHz, respectively. The relationship between the properties and the microstructure of co‐PI fibers after heat‐drawing was investigated. The results revealed that the hydrogen‐bond associations and the microvoids structure were highly affected by imidization conditions. Both the formations of the hydrogen‐bond associations and the evolution of microvoids were attributed to the change in tensile strength. Furthermore, the fibers prepared at proper conditions possessed fewer surface defects as well as homogeneous inner structure. Our work demonstrates the structure–property relationship in annealed PI fibers, which may provides a new avenue to access high‐performance PI fibers.