PAN原丝取向行为与初生纤维结构的相关性
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摘要
通过改变浓度、温度等凝固浴条件,获得取向行为不同的PAN原丝,采用声速法测定原丝的取向结构,使用X射线衍射仪、光学显微镜对PAN初生纤维的聚集态结构、截面形貌进行表征,建立原丝取向与初生纤维结构的相关性。依据取向度随牵伸倍数变化对数拟合曲线的斜率,定义原丝的分子链取向能力a,研究a与初生纤维结晶度的关联性。结果表明:初生纤维结晶度越高,PAN原丝可牵伸性越小,在同一牵伸倍数下纤维全取向度越高;原丝最大牵伸倍数受初生纤维径向结构影响显著,在凝固浴浓度74%时出现极大值;高溶剂含量的纤维分子链取向能力大于低溶剂含量的纤维;原丝的分子链取向能力随初生纤维结晶度增大而增大。
Polyacrylonitrile(PAN) precursors with different orientation behaviors were prepared by changing the coagulation bath conditions such as concentration and temperature. The orientation structure of the PAN precursor was determined by the method of sound velocity. X-ray diffraction and optical microscopy were used to investigate the crystalline structure and morphological characterization of nascent fiber, and the correlation between orientation of precursor and structure of nascent fiber was established. The molecular chain orientation ability "a" was defined as the slope of the logarithmic fitting curve of the degree of orientation varying with the drafting ratio, and the relationship between "a" and the crystallinity of nascent fiber was studied. The results show that the higher crystallinity nascent fiber has, the lower drawing ability PAN precursor has, and the higher degree of orientation has under the same drafting ratios. The maximum drafting factor of polyacrylonitrile precursor is significantly affected by radial structure of nascent fiber, it reaches the local maximum when the coagulation bath concentration is 74%. The fiber with high solvent content has higher molecular chain orientation ability than the fiber with low solvent content.The molecular chain orientation ability of precursor increases with the crystallinity of nascent fiber.
Polyacrylonitrile(PAN) precursors with different orientation behaviors were prepared by changing the coagulation bath conditions such as concentration and temperature. The orientation structure of the PAN precursor was determined by the method of sound velocity. X-ray diffraction and optical microscopy were used to investigate the crystalline structure and morphological characterization of nascent fiber, and the correlation between orientation of precursor and structure of nascent fiber was established. The molecular chain orientation ability "a" was defined as the slope of the logarithmic fitting curve of the degree of orientation varying with the drafting ratio, and the relationship between "a" and the crystallinity of nascent fiber was studied. The results show that the higher crystallinity nascent fiber has, the lower drawing ability PAN precursor has, and the higher degree of orientation has under the same drafting ratios. The maximum drafting factor of polyacrylonitrile precursor is significantly affected by radial structure of nascent fiber, it reaches the local maximum when the coagulation bath concentration is 74%. The fiber with high solvent content has higher molecular chain orientation ability than the fiber with low solvent content.The molecular chain orientation ability of precursor increases with the crystallinity of nascent fiber.
引文
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[2]贺福.碳纤维及其应用技术[M].北京:化学工业出版社,2004.(HE F.Carbon fiber and its application technology[M].Beijing:Chemical Industry Press,2004.)
[3]贾存龙.高分子量聚丙烯腈湿法纺丝工艺研究[D].北京:北京化工大学,2011.(JIA C L.Study on wet-spinning process of high molecular weight PAN precursor[D].Beijing:Beijing University of Chemical Technology,2011.)
[4]YU M J,WANG C G,BAI Y J,et al.Combined effect of procession parameters on thermal stabilization of PAN fibers[J].Polymer Bulletin,2006,57:757-763.
[5]葛曷一,柳华实,陈娟.湿法纺聚丙烯腈原丝的微观结构分析[J].材料工程,2009(7):50-53.(GE H Y,LIU H S,CHEN J.Microstructure of PANprecursor fibers in wet-spinning[J].Journal of Materials Engineering,2009(7):50-53.)
[6]李龙,王梦梵,焦娜,等.力场对PAN干湿法/湿法初生纤维结晶及其取向结构的影响[J].高分子通报,2014(1):43-48.(LI L,WANG M F,JIAO N,et al.The effect of the force field on the crystalline and orientation structure of PAN nascent fiber during dry jet wet-spinning and wetspinning processes[J].Chinese Polymer Bulletin,2014(1):43-48.)
[7]CHEN J,WANG C G,DONG X G,et al.Study on the coagulation mechanism of wet-spinning PANfibers[J].Journal of Polymer Research,2006,13:515-519.
[8]董兴广.聚丙烯腈纤维纺丝成形机理及工艺相关性研究[D].济南:山东大学,2009.(DONG X G.Study on spinning formation mechanism and processing of polyacrylonitrile fibers[D].Jinan:Shandong University,2009.)
[9]彭公秋,温月芳,杨永岗,等.影响湿纺PAN初生纤维取向和性能因素的探讨[J].化工新型材料,2009,37(2):89-91.(PENG G Q,WEN Y F,YANG Y G,et al.Discussion of influential factors on the orientation and properties of PAN nascent fibers[J].New Chemical Materials,2009,37(2):89-91.)
[10]李婷,武帅,崔东旭,等.溶液特性对聚丙烯腈初生纤维凝聚态形成的影响[J].化工新型材料,2015,43(2):89-92.(LI T,WU S,CUI D X,et al.Influence of solution property on the formation of aggregation structure of polyacrylonitrile nascent fibers[J].New Chemical Materials,2015,43(2):89-92.)
[11]王贺团,李常清,石鑫,等.PAN/DMSO溶液的挤出对初生纤维结构的影响[J].合成纤维工业,2009,32(4):4-6.(WANG H T,LI C Q,SHI X,et al.Effect of PAN/DMSO solution extrusion on structure of as-spun fiber[J].China Synthetic Fiber Industry,2009,32(4):4-6.)
[12]朱镇.PAN初生纤维聚集态结构形成机理及调控[D].北京:北京化工大学,2013.(ZHU Z.The regulation and the forming mechanism of PAN nascent fiber accumulative state[D].Beijing:Beijing University of Chemical Technology,2013.)
[13]朱镇,袁俊崧,肖阳,等.凝固浴中物质极性对PAN结晶度的影响[J].高分子通报,2013(2):51-55.(ZHU Z,YUAN J S,XIAO Y,et al.Effect of substance polarity in coagulation bath on PANcrystallinity[J].Chinese Polymer Bulletin,2013(2):51-55.)
[14]韩曙鹏,徐樑华,曹维宇,等.成纤过程中PAN纤维聚集态结构的形成[J].新型炭材料,2006,21(2):54-58.(HAN S P,XU L H,CAO W Y,et al.Aggregate states of PAN in the process of fiber formation[J].New Carbon Materials,2006,21(2):54-58.)
[15]ISMAIL A F,RAHMAN M A,MUSTAFA A,et al.The effect of processing conditions on a polyacrylonitrile fiber produced using a solvent-free coagulation process[J].Materials Science and Engineering,2008:251-257.
[16]励杭泉,张晨,张帆.高分子物理[M].北京:中国轻工业出版社,2009:139-141.(LI H Q,ZHANG C,ZHANG F.Polymer physics[M].Beijing:China Light Industry Press,2009:139-141.)