| Quality of polyacrylonitrile (PAN) precursor is the premise of producing high performance carbon fiber (CF), high molecular weight PAN spinning is the fundamental way to improve the precursor performance. This paper adopts the mixed solvent method, in this paper with Diisopropyl azodicarboxylate (AIBN) as initiator, methyl acrylate (MA) that can be properly reduced intermolecular forces and reinforced fiber softness and handle as the second monomer; itaconic acid (IA) that the introduce polar groups and improve fiber dyeing performance as the third monomer. Different mixed solvent water/dimethyl sulfoxide (H2O/DMSO), ethanol/dimethyl sulfoxide (C2H5OH/DMSO), and n-butyl alcohol/dimethyl sulfoxide (C4H9OH/DMSO) as solvent synthesize PAN by mixed solvent in precipitation polymerization. In other side, DMSO and H2O as solvent synthesize PAN by mixed solvent in precipitation homogeneous polymerization. We know isotactic PAN has an important impact on the pre-oxidation, and therefore following the study on the basis of pre-doctoral research isotactic polymerization of isotactic PAN pre-oxidation process, the main works in the study are as follows:1. Molecular weight of homopolymerization and copolymerization and its contrast, analysis of the factors affecting molecular weight; the molecular weight of copolymerization is higher than the homopolymerization, should be used to gather legitimate to fabricate high-performance, high-quality precursor is made by mixed solvent in precipitation.2. The molecular weight of PAN is very high by mixed solvent in precipitation, high molecular weight, viscosity of the spinning solution is big, is not conducive to spinning, so we need to adjust the molecular weight, but the literature on the molecular weight regulator is obviously reported, so we control and regulate molecular weight by using C2H5OH and C4H9OH as solvent.3. According to sub-cluster statistical theory, we obtained the relationship between the solvent surface tension(γ), and cohesive energy density (ECED):In γ/M=A0+k0ECED according to a variety of solvent surface tension and cohesiveenergy density data, we verify its correctness, and have a good linear relationship.4. Uniform paricle size distribution, easy to make uniform spinning solution, provided an important condition for the stability of the subsequent spinning process, uneven paricle size distribution, the dissolution time heterogeneity, poor solubility, poor precursor formed, ultimately affecting the performance of precursor and carbon fiber. According to their morphology study on the relationship between particle size distribution and uniformity of high molecular weight PAN on the basis of statistical parameters of the Fourth Statistics-JRG Sub-cluster Statistics Theory. The results show that particle size uniformity has nothing to do with the mixed solvent but is related to the ratio of mixed solvent, the less the content of DMSO, the more homogeneous particle size distribution is.5. According to sub-cluster statistical theory, investigated from a theoretical point of view process of isotactic polyacrylonitrile oxidation and ring structured in the pre-oxidation process and derive the trend of the activation energy. By examining the TG data of isotactic polyacrylonitrile from32℃-297℃, calculated the competitive relationship of the ring structure and oxidation in the pre-oxidation process. Isotactic polyacrylonitrile through research showed that in the pre-oxidation process, at the low temperature oxidation stage through an oxygen atom to the ring structure of the trend is more obvious than carbon-carbon ring structure. But in the medium term of pre-oxidation, carbon-carbon and oxygen-carbon ring structure isn’t only fairly easy, but also pure oxygen consumption rate and oxygen-carbon ring structure is fairly easy; while the latter part of the pre-oxidized, carbon carbon ring structured and oxygen-carbon ring structure are accelerated, by contrast, when pure oxygen consuming reaction in a secondary position. |
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