可纺沥青化学结构差异对其流变、纺丝及衍生碳纤维性能的影响OA

The structure and composition of a spin-nable pitch determine the properties of the carbon fibers produced from it.Spinnable pitches with low and high softening points(L-SP and H-SP)were pre-pared by air-blowing thermal polymerization of coal tar pitch.The polymerization mechanism,structural composition,properties of the pitch,and the carbon fiber properties were investigated by fluorescence excitation-emission spectroscopy with parallel factor analysis,EPR,13C-NMR,dynamic shear rheometry,XRD,Raman,etc.L-SP had the lower degree of polymerization,longer alkyl side chains,and a high-er proportion of C―O―C groups.At its spinning temperature,the molten L-SP had viscous-dominant rheological characteristics.H-SP had larger polycyclic aromatic hydrocarbon rings,a higher degree of branching,and a higher polarity.The molten H-SP had a high storage and loss moduli,and a rheological behavior with nearly balanced viscous and elastic properties.Although carbon fibers prepared from H-SP had the better physical properties,their inferior rheological prop-erties could lead to melt die swelling,the formation of surface particles and an increased number of irregularities.The superior viscoelasticity of L-SP promoted uniform stretching,maximizing the properties of carbon fibers.This ultimately resulted in similar tensile strengths and moduli of the carbon fibers prepared from the two pitches.The high-quality spinnable pitch had a high aromatic carbon content,a small size of its PAHs,and a low C=O/O―C=O content,which ensured viscosity-dominated rheological behavior,thereby reducing die swelling and melt fracture,and the spinning stability and properties of the carbon fibers produced were improved.