扁平腈纶湿法成形过程中的挤出胀大行为的模拟

应用Polyflow软件通过理论模拟的方法,对扁平腈纶(PAN纤维)湿法成形过程中的挤出胀大行为进行模拟,建立了喷丝孔口挤出胀大比与纺丝工艺参数之间的关系,研究了纺丝温度、喷头挤出速度、负拉伸率、凝固浴温度等工艺参数对挤出胀大比的影响规律。结果表明:挤出胀大比随着挤出速度、负拉伸率的增大而增大,随着纺丝温度的增大而减小,而挤出胀大比受凝固浴温度的影响较小;对模拟结果进行了实验验证,在喷丝板为0. 1 mm×0. 04 mm、板厚为1 mm、纺丝温度40℃、凝固浴温度10℃、凝固浴质量分数14%、入口流量2. 21×10~(-3)mL/s、喷丝头负拉伸率为-43%的条件下,纺丝制得的扁平PAN纤维的扁平度达到6. 4,线密度为11 dtex,且可纺性好,模拟结果具有合理性。     

次氯酸钠处理多孔PAN纤维的结构与吸附性能研究

以聚丙烯腈/聚乙烯吡咯烷酮/二甲基亚砜(PAN/PVP/DMSO)三元体系为纺丝液,以DMSO/H_2O为凝固浴,在凝固浴温度为60℃下,通过湿法纺丝制备了具有介孔结构的多孔PAN/PVP纤维;用次氯酸钠(NaClO)对多孔PAN/PVP纤维进行处理,制得了NaClO@PAN/PVP纤维,采用场发射扫描电镜、元素分析仪和氮气气体吸附仪对处理前后纤维的表面形貌、元素组成、比表面积和孔径进行了表征,研究了凝固浴浓度和温度对PAN/PVP纤维和NaClO@PAN/PVP纤维的PVP含量及比表面积和孔径的影响。结果表明:经NaClO处理后,NaClO@PAN/PVP纤维中氧含量减少,氮含量增多,PVP含量减少,纤维表面变得光滑,平均孔径减小,孔数增多,比表面积增大;随着凝固浴DMSO浓度增大或温度升高,PAN/PVP纤维,NaClO@PAN/PVP纤维中的PVP含量降低,但其比表面积随凝固浴浓度的增大而减小,随凝固浴温度的升高而先升高后减小;在凝固浴DMSO质量分数为0,温度为60℃的条件下制得的PAN纤维、PAN/PVP纤维、NaClO@PAN/PVP纤维的比表面积分别为38,96,108 m~2/g,平均孔径分别为22.7,20.4,19.0 nm;PAN/PVP纤维、NaClO@PAN/PVP纤维的最可几孔径分布在40 nm左右,属于介孔结构。     

聚丙烯腈中空纤维膜的纺制及其应用

PAN中空纤维膜是一种具有高附加价值和广泛用途的功能纤维。本文以PAN—DMSO—添加剂溶液纺制成PAN中空纤维膜,并探讨了纺丝方法和纺丝工艺;用扫描电镜观察了PAN中空纤维膜的形态结构,并解释了成膜机理;从三个方面探索了PAN中空纤维膜的应用,取得了满意的结果。     

凝固浴对PAN原丝性能的影响

在生产聚丙烯腈(PAN)炭纤维过程中,纺丝期间凝固浴的各种条件对纤维的成型和性能起着关键作用。本文介绍PAN高聚物在湿法一步法纺丝过程中二甲基亚砜(DMSO)凝固浴各种成型工艺条件对PAN原丝的结构、机械和物理性能的影响。     

凝固条件对PAN初生纤维微结构的影响

通过湿法纺丝工艺制备聚丙烯腈(PAN)初生纤维,借助于X射线衍射仪、声速仪、扫描电子显微镜、小角X光散射仪等,研究了凝固浴温度、凝固浴浓度、喷丝头拉伸等凝固条件对初生纤维晶态结构、取向结构、形态结构的影响。结果表明:PAN纤维的凝聚态结构和形态结构在初生纤维形成时已基本形成;PAN初生纤维的结晶度达40%以上,其结晶度和结晶尺寸受凝固浴温度和浓度的影响;PAN初生纤维和原丝的晶区取向和全取向随着喷丝头拉伸的增大而增大;PAN初生纤维具有沿纤维轴向高度取向的沟槽,通过改变成形条件,可以获得沟槽浅且规整性完美的纤维表面;提高凝固浴浓度,可以形成结构均质、致密的PAN初生纤维,避免皮芯结构及芯部出现较多孔洞。     

凝固浴氨化对PAN湿法纺丝凝固行为的影响

在二甲基亚砜/水(DMSO/H_2O)凝固体系中加入氨水,以pH值控制凝固浴氨化程度,研究了凝固浴氨化对聚丙烯腈(PAN)湿法纺丝凝固行为的影响;采用扫描电子显微镜表征PAN初生纤维的皮层结构,采用卡尔费休水分仪和气相色谱仪研究了氨化对水和DMSO扩散系数的影响。结果表明:当凝固浴pH值为8.0时,PAN初生纤维的皮层最薄;随着凝固浴pH值的增大,水的扩散系数逐渐减小,DMSO的扩散系数(D_(DMSO))先减小后增大,当pH值为8.0时,D_(DMSO)出现最小值;氨化的作用机理是通过氨与水和DMSO分子间的氢键作用来实现的。     

三角形PAN纤维湿法纺丝工艺研究

采用三角形喷丝板,以二甲基亚砜为溶剂,进行聚丙烯腈(PAN)湿法纺丝。探讨凝固成形条件及后拉伸对三角形PAN纤维截面形状、声速和力学性能的影响。结果表明:随着凝固浴浓度的升高,PAN初生纤维的异形度降低,声速和力学性能均先升高后降低;随着凝固浴温度的升高,PAN初生纤维的异形度增大,声速和力学性能均降低;随着喷丝头拉伸比的增加,PAN初生纤维的异形度增加,声速和力学性能也都呈上升趋势,随着后拉伸的进行,三角形PAN纤维的异形度基本保持不变,其力学性能和声速均逐渐升高。     

聚丙烯腈原丝的凝固成形与相分离研究进展

以热力学相图为工具,探讨了聚丙烯睛(PAN)原丝凝固成形过程。从相图中原丝凝固成形的不同途径和相应的织态结构可以知道,原液体系以旋节方式分相是最佳的热力学路径。原丝凝固成形可以看作是浓度致变相分离(CIPS)和热致变相分离(TIPS)两种相分离形式的组合,通过后者得到高性能原丝要容易实现得多。可以根据相图来优化纺丝工艺条件,通过调节凝固浴浓度、纺丝液浓度、初始纺丝温度以及淬火深度.削弱CIPS过程在凝固成形中的作用,使凝固成彤尽可能多的以TIPS方式通过旋节线和双节线的交界处进行,以得到具有理想结构的优质的PAN原丝。     

湿纺凝固负拉伸对初生纤维结构与性能的影响

研究了凝固负拉伸对聚丙烯腈(PAN)纺丝液的膨胀效应、初生纤维聚集态结构和性能的影响,初步揭示了膨胀效应和凝固取向的产生机理及其对初生纤维结构与性能的影响;指出溶剂与水之间的传质速率差是控制初生纤维结构进而控制其性能的最关键因素,它决定了原液细流表面凝固层的组成及结构,而凝固速率反映了凝固层的生长速度。研究发现:随着凝固负拉伸的降低,PAN纺丝液的挤出胀大比减小,其传质速率差与凝固速率均下降,初生纤维的凝固取向、结晶度和晶粒尺寸均增加,其截面形状趋于圆形,内部结构变得均匀致密、缺陷减少,从而使断裂强度得以提高。     

专利产品

一种氧化铝基陶瓷中空纤维膜制备方法 本发明涉及一种增强型氧化铝基陶瓷中空纤维膜的制备方法。将主体膜材料氧化铝粉料和增强剂进行球磨混合，之后干燥研磨过筛。配制聚合物溶液，把混合均匀的陶瓷粉料加入其中并分散均匀，得到适宜粘度的纺丝液。纺丝液脱泡处理后由喷丝头挤出，经过一定干纺程进入外凝固浴，此期间发生相分离过程，同时形成中...     

湿法腈纶质量控制的影响因素

浅析了影响腈纶生产质量稳定的控制因素,主要包括原液质量、纤维成形工艺等。正常生产中,控制聚丙烯腈(PAN)浆化液质量分数为26%,PAN溶液质量分数为13.5%,凝固浴硫氰酸钠质量分数为8%～12%,以及严格控制其他工艺条件,有利于生产稳定。     

Investigating the jet stretch in the wet spinning of PAN fiber

The jet stretch of wet‐spun PAN fiber and its effects on the cross‐section shape and properties of fibers were investigated for the PAN‐DMSO‐H₂O system. Evidently, the spinning parameters, such as dope temperature, bath concentration, and bath temperature, influenced the jet stretch. Also, under uniform conditions, the postdrawing ratio changed as well as that of jet stretch. When coagulation temperature was 35°C simultaneously with bath concentration of 70%, jet stretch impacted obviously the cross‐section shapes of PAN fiber, but had little effect when the temperature was below 10°C or above 70°C. As the jet stretch ratio increased, the crystallinity, crystal size, sonic orientation, and mechanical properties of the as‐spun fiber changed rapidly to a major value for jet stretch ratio of 0.9 where the cross section of as‐spun fiber was circular. With further increasing of jet stretch ratio, the properties changed slightly but the fiber shape was not circular. The results indicated that appropriate jet stretch, under milder formation conditions in wet‐spinning, could result in the higher postdrawing ratio and circular profile of PAN fiber, which were helpful to produce round PAN precursor with minor titer and perfect properties for carbon fiber. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

细旦腈纶的生产

研究细旦腈纶的纺丝工艺条件。并在纺丝线上进行试生产。讨论了纺丝原液温度、凝固浴条件、喷丝板负拉伸率、总收缩率、总拉伸倍数、纺丝速度对细旦腈纶质量和生产稳定性的影响。工业化试验表明:纺制0.89 dtex细旦腈纶的主要工艺条件为,纺丝原液温度74~76℃,喷丝板负拉伸率70％,总收缩率23%~25％,总拉伸倍数15,纺丝速度155m/min以及适当的凝固浴条件。     

三元共聚聚酰亚胺初生纤维结构与性能的研究

以BTDA-TDI/MDI(P84)三元共聚聚酰亚胺(PI)粉末为原料,采用湿法纺丝技术制备BTDA-TDI/MDI三元共聚PI初生纤维,并对其结构和性能进行表征。实验结果表明:三元共聚PI初生纤维的最高抗断裂强度为0.65 cN/dtex;纺丝浆液PI质量分数19%时所得初生纤维表面较光滑;凝固浴溶液NMP质量分数70%时初生纤维结晶度分别比质量分数60%和80%时结晶度大;不同NMP质量分数凝固浴溶液所得初生纤维的热稳定性相差不大。     

Integrally skinned polysulfone hollow fiber membranes for pervaporation

From polysulfone as polymer, integrally skinned hollow fiber membranes with a defect-free top layer have been spun. The spinning process described here differs from the traditional dry-wet spinning process where the fiber enters the coagulation bath after passing a certain air gap. In the present process, a specially designed tripple orifice spinneret has been used that allows spinning without contact with the air. This spinneret makes it possible to use two different nonsolvents subsequently. During the contact time with the first nonsolvent, the polymer concentration in the top layer is enhanced, after which the second coagulation bath causes further phase separation and solidification of the ultimate hollow fiber membrane. Top layers of ± 1 μm have been obtained, supported by a porous sublayer. The effect of spinning parameters that might influence the membrane structure and, therefore, the membrane properties, are studied by scanning electron microscopy and pervaporation experiments, using a mixture of 80 wt % acetic acid and 20 wt % water at a temperature of 70°C. Higher fluxes as a result of a lower resistance in the substructure could be obtained by adding glycerol to the spinning dope, by decreasing the polymer concentration, and by adding a certain amount of solvent to the bore liquid. Other parameters studied are the type of the solvent in the spinning dope and the type of the first nonsolvent. © 1994 John Wiley & Sons, Inc.     

Investigation the jet stretch in PAN fiber dry‐jet wet spinning for PAN‐DMSO‐H2O system

The jet stretch of dry‐jet wet spun PAN fiber and its effects on the cross‐section shape of fibers were investigated for a PAN‐DMSO‐H₂O system. Clearly, the spinning parameters, such as dope temperature, bath concentration, bath temperature, and air gap, all influenced the jet stretch. Also, under uniform conditions, the postdrawing ratio as well as that of jet stretch changed. Under given conditions, as the bath temperature was below 30°C or above 45°C, jet stretch had little effect on the cross‐sectional shapes of PAN fiber. Within the temperature of 30–45°C, fiber's cross‐section shapes change obviously from round over an approximate circular shape into to an elliptical or a flat shape. The scope of jet stretch produced PAN fiber with circular cross‐section was bigger than that in wet spinning. These results indicated that appropriate air gap height, under milder formation conditions in dry‐jet wet spinning, could result in higher jet stretch and higher postdrawing ratio. The appropriate jet stretch and postdrawing ratio could result in circular profile of PAN fiber, which were helpful to produce round PAN precursor with finer size and better properties for carbon fiber. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

干湿纺中聚丙烯腈原丝凝固成形的探讨

介绍了聚丙烯腈（PAN）碳纤维原丝在以温度为主导的热致变和浓度为主导的双扩散致变下的成形过程,分析了凝固pH及牵伸率等对凝固成形的影响,并对干湿纺下淬火成膜,膜内液滴变化、细颈区拉伸等作出新的解释,从而对干湿纺下凝固成形的机理有一定的宏观把握,为纺出高品质的PAN原丝奠定理论基础.