Patent ID: 11873584
Assignee: DEAKIN UNIVERSITY
Field: Textile and paper machines (Mechanical engineering)
Classification: CPC D  C | IPC C  D

Claim 8:
9. A process for preparing a carbon fibre comprising the steps of:
providing a stabilised precursor fibre prepared according to a process comprising
heating a precursor comprising polyacrylonitrile at a temperature in a range of from 250° C. to 400° C. in a substantially oxygen-free atmosphere containing not more than 0.005% by volume of an oxygen containing molecule while applying a substantially constant amount of tension that varies by less than 5% to the precursor to promote cyclisation of nitrile groups in the precursor, the temperature and time period in which the precursor is heated in the substantially oxygen-free atmosphere and the amount of tension applied to the precursor each being selected to form a pre-stabilised precursor having at least 10% cyclised nitrile groups (EOR (%)) as determined by Fourier transform infrared (FT-IR) spectroscopy using the following equation:, EOR
   ⁢
      
   
    (
    %
    )
   
  
  =
  
   
    (
    
     100
     ×
     0.29
     ×
     
      Abs
      ⁡
      (
      1590
      )
     
    
    )
   
   
    (
    
     (
     
      
       Abs
       ⁡
       (
       2242
       )
      
      +
      
       (
       
        0.29
        ×
        
         Abs
         ⁡
         (
         1590
         )
        
       
       ), where Abs (1590) and Abs (2242) are absorbance peaks recorded at 1590 cm−1 and 2242 cm−1, which correspond to C═N groups and nitrile (—CN) groups, respectively; and
exposing the pre-stabilised precursor to an oxygen containing atmosphere at a temperature in a range of from 200° C. to 300° C. to form the stabilised precursor in a time period of no more than 25 minutes, wherein prior to the pre-stabilised precursor being exposed to the oxygen containing atmosphere it is cooled to a temperature below the temperature of the oxygen containing atmosphere; and
carbonising the stabilised precursor fibre to form the carbon fibre.