Polyimide fibre containing benzimidazole structure and preparation method thereof

The invention discloses polyimide fiber with benzimidazole structure, which is characterized in that the infrared spectrum of the fiber is provided with character absorption peaks of imide ring of 1776-1774cm, 1726-1722cm and 1378-1373cm within the wave number range of 1300-1800cm and N-H functional group absorption wide peaks in the imidazole structure within the wave number range of 3000-3750cm. The tensile strength is 0.73-1.53GPa. The initial modulus is 45.2-220GPa. The invention also provides a preparation method of the fiber. The fiber disclosed by the invention contains the benzimidazole structure with secondary amine hydrogen. Therefore, compared with PMDA-ODA polyimide fiber prepared with the same process, the tensile strength can be improved by nearly three times at the most, the initial modulus can be improved by more than twenty times at the most, and the heat resistance is further improved. The preparation method provided by the invention has the advantages of mature technolog