Pan Preoxidation Fibers Carbonization Tar To Eliminate And Control Research

The elimination and controlment of Polyacrylonitrile (PAN) carbon fiber carbonization tar can make carbon fiber not be polluted by impurities and improve its structure and properties during the process of manufacture. The paper analyzed the forming reactions and components of the tar and discussed the design schemes to eliminate and control it by chemical reagents from different points of view. The effective technology was optimally chosen based on diverse properties testing and experimental analyzing. Computer simulation was laso used to demonstrate the technology. The technology exploration provided preparations for developing PAN-based carbon fiber with high performance.The tar generated from PAN pre-oxidized fiber pyrolysis during carbonization process was a kind of complicated admixture composing of a great deal of components. By thermal analysis, pyrolysis of pre-oxidized fiber and gas chromatography-mass spectrometry, and infrared spectra analysis of the tar sample, the compositions of the tar were confirmed. Pentanedinitrile, hexanedinitrile, 2-methyl-pentanedinitrile, 1,3-dimethyl-pentanedinitrile etc acrylonitrile dimer series components and 1,2-benzenedicarbonitrile, 1,3,5-benzenetricarbonitrile, 1,3,5-trimethylcyclohexane, l,2-dicarbonitrile-4- amino-benzene etc acrylonitrile trimer series components were main compositions, trace cycloalkanes and quinoline, pyridine etc compounds containing O,N atoms were also included.The forming mechanism of the tar was established by PAN pre-oxidized fiber infrared spectra, element and EPR (Electron Paramagnetic Resonance) analysis and according to polymer pyrolysis reaction principle, in which linear chains among PAN trapeziform structure polymer pyrolysis in random was central reaction accompanied with atoms transfer between atoms in different chains and second reactions in high temperature.Infrared spectra anaysis to elaminate the tar was carried out from the point of view of residue nitriles hydrolyzing in hydrochloric acid, sulfuric acid mixed solution and sodium hydroxide solution. Infrared spectra and thermal analysis were also used to explain free radical electrons transferring among pyrolysis chains taking place in methyl alcohol and diethyl amine treatments. Considering the treatments effect on polymer structure, operation circumstance and the test performance contrasting, the mixed acid pretreatment was determined as the...