在惰性气氛条件下,将PAN原丝在180-280℃进行恒温热处理.通过傅里叶变换红外、13C固体核磁共振方法研究了PAN纤维在热稳定化过程中的结构演变规律,并对PAN纤维的热稳定化反应进程进行了探索.结果表明:随着热处理温度升高,共聚单体中的羧基首先引发环化交联反应;在220℃左右开始发生剧烈的环化交联反应;当热处理温度高于240℃时,环化交联反应趋于平缓,脱氢反应逐渐占据主导地位.通过差式扫描量热仪、热重-质谱联立分析仪和元素分析仪分别研究了不同热稳定化阶段PAN纤维的剩余焓变量、H2的选出量及纤维中剩余H元素的含量.结果进一步佐证了提出的热稳定化反应进程.牵伸实验表明,张力越大,PAN纤维初期的热稳定化进程越缓慢.
参考文献
| [1] | Watt W;Johnson W .Mechanism of oxidation of polyacrylonitrile fibers[J].Nature,1975,257:210-212. |
| [2] | Sivy G T;Gordon B;Coleman M M .Studies of the degradation of copolymers of acrylonitrile and aerylamide in air at 200℃-speculations on the role of the preoxidation step in carbon fiber formation[J].CARBO,1983,21(06):573-578. |
| [3] | Coleman M M;Sivy G T;Painter P C et al.Studies of the degradation of acrylonitrile/acrylamide copelymers a function of compositing and temperature[J].CARBO,1983,21(03):255-267. |
| [4] | Fitzer E;Frohs W;Heine M .Optimization of stabilization and carbonization treatment of PAN fibers and structural characterization of the resulting carbon fibers[J].CARBO,1986,24(04):387-394. |
| [5] | Bajaj P;Sreekumar T V;Sen K .Thermal behavior of acrylonitrile copolymers having methacrylic and itaconic acid comonomers[J].Polymers,2001,42(04):1707-1718. |
| [6] | Ouyang Q;Cheng L;Wang HJ;Li KX .Mechanism and kinetics of the stabilization reactions of itaconic acid-modified polyacrylonitrile[J].Polymer Degradation and Stability,2008(8):1415-1421. |
| [7] | Usami T;Itoh T;Ohtani H et al.Structure study of polyacrylonitrile fibers during oxidative thermaldegradation by pyrolysis-gas chromatography,solid-state 13C nuclear magnetic resonance,and fourier transform infrared spectroscopy[J].Macromolecules,1990,23:2460-2465. |
| [8] | Fochler H S;Mooney I R;Ball L E et al.Infrared and NMR spectroscopic studies of the thermal degradation of polyacrylonitrile[J].Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy,1985,41:271-278. |
| [9] | Kakida H.;Tashiro K. .Mechanism and kinetics of stabilization reactions of polyacrylonitrile and related copolymers - IV. Effects of atmosphere on isothermal DSC thermograms and FTIR spectral changes during stabilization reaction of acrylonitrile methacrylic acid copolyme[J].Polymer Journal,1998(6):463-469. |
| [10] | Collins G L;Thomas N W;Williams G E .Kinetics relationships between heat generation and nitrile consumption in the reaction of poly(acrylonitrile)in air at 265℃[J].CARBO,1988,26(05):671-679. |
| [11] | Martin SC.;Snape CE.;Liggat JJ. .In situ NMR investigation into the thermal degradation and stabilisation of PAN[J].Polymer Degradation and Stability,2001(3):407-412. |
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