PAN纤维在惰性气氛中的热行为研究
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摘要
聚丙烯腈(PAN)纤维在惰性气氛中的热行为主要包括3个反应:热致收缩反应、环化反应和热解反应。通过差示扫描量热仪和热重分析仪研究了PAN纤维在惰性气氛中的热行为。结果表明,热致收缩和热解反应并无明显的吸放热现象,而环化反应放热剧烈且短促。环化反应过程中存在明显的传热过程,环化反应速率达到最大值时,温度随着升温速率的提高而上升。热解反应使得可发生环化反应的原料总量下降,且随着升温速率的提高,反应放热量下降。分别采用Ozawa法与Kissinger法计算了环化反应的表观活化能,并建立了修正后的动力学模型。该模型可以有效地描述不同升温速率条件下的反应过程。
The thermal behavior of PAN precursor under inert atmosphere consisted of heat-inducing shrinking,cyclization reaction and pyrolysis reaction.The thermal behavior of PAN precursor was discussed with differential scanning calorimetry(DSC)and thermal gravimetric analysis(TG).The results showed that there were not any obvious endothermal or exothermal phenomena during heat-inducing shrinking or pyrolysis reaction,while cyclization reaction given out massive heat with short duration.The temperature of cyclization reaction reached maximum with the increase of heating rate,which indicated that there was a heat conduction process within PAN precursor during the rise of heat treatment temperature.The total heat release droped with the increase of heating rate,which proved that the pyrolysis reaction consumed some of the PAN precursor that could have cyclized.Ozawa method and Kissinger method were used to calculate the apparent activation energy during cyclization reaction,and corrected kinetic model was established.The result showed that the model formula can describe situations with different heating rate.
The thermal behavior of PAN precursor under inert atmosphere consisted of heat-inducing shrinking,cyclization reaction and pyrolysis reaction.The thermal behavior of PAN precursor was discussed with differential scanning calorimetry(DSC)and thermal gravimetric analysis(TG).The results showed that there were not any obvious endothermal or exothermal phenomena during heat-inducing shrinking or pyrolysis reaction,while cyclization reaction given out massive heat with short duration.The temperature of cyclization reaction reached maximum with the increase of heating rate,which indicated that there was a heat conduction process within PAN precursor during the rise of heat treatment temperature.The total heat release droped with the increase of heating rate,which proved that the pyrolysis reaction consumed some of the PAN precursor that could have cyclized.Ozawa method and Kissinger method were used to calculate the apparent activation energy during cyclization reaction,and corrected kinetic model was established.The result showed that the model formula can describe situations with different heating rate.
引文
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[3]于美杰,王成国,朱波,等.聚丙烯腈基碳纤维原丝热稳定化研究进展[J].材料工程,2006(11):62-66.
[4]Yusof N,Ismail A F.Post spinning and pyrolysis processes of polyacrylonitrile(PAN)-based carbon fiber and activated carbon fiber:a review[J].Journal of Analytical &Applied Pyrolysis,2012,93(1):1-13.
[5]肖士洁,昌志龙,童元建,等.聚丙烯腈纤维热稳定化反应动力学研究[J].北京化工大学学报:自然科学版,2011,38(1):87-91.
[6]Rahaman M S A,Ismail A F,Mustafa A.A review of heat treatment on polyacrylonitrile fiber[J].Polymer Degradation&Stability,2007,92(8):1421-1432.
[7]Ko T H,Lin C H,Ting H Y.Structural changes and molecular motion of polyacrylonitrile fibers during pyrolysis[J].Journal of Applied Polymer Science,2010,37(2):553-566.
[8]Xiao S,Lv H,Tong Y,et al.Thermal behavior and kinetics during the stabilization of polyacrylonitrile precursor in inert gas[J].Journal of Applied Polymer Science,2011,122(1):480-488.
[9]于美杰,吴益民,朱波,等.聚丙烯腈纤维预氧化过程中氧化反应和环化反应的动力学研究[J].中南民族大学学报:自然科学版,2011,30(1):29-32.
[10]李常清,杨策宇,马晓娜,等.成纤过程对PAN纤维晶态结构的影响[J].高分子材料科学与工程,2013,29(1):104-106.
[11]杨波,张红波,汪学锋.某国产聚丙烯腈原丝的预氧化研究[J].中南大学学报:自然科学版,2011,42(11):3320-3325.
[12]Ozawa T.A new method of analyzing thermogravimetric data[J].Bulletin of the Chemical Society of Japan,1965,38(11):1881-1886.
[13]Kissinger H E.Reaction kinetics in differential thermal analysis[J].Analytical Chemistry,1957,29(11):1702-1706.
[14]Malek J,Criado J M.Empirical kinetic models in thermal analysis[J].Thermochimica Acta,1992,203:25-30.
[15]张竞,李全步,蒋英,等.非等温DSC法研究高韧性低收缩环氧体系固化动力学[J].高分子材料科学与工程,2009,25(6):99-102.
[16]田建军,张学军,田艳红,等.改性氰酸酯树脂体系的固化动力学[J].高分子材料科学与工程,2012,28(9):36-39.
[17]樊孟金,谭家顶,刘嘉林,等.风电叶片用低粘度环氧树脂体系固化反应动力学[C].北京粘接学会学术年会暨粘接技术创新与发展论坛,2012.