Evaluation of the requirements for the rheological characteristics of the polymer solution for production of high-strength polyaramid fibres

Rheological studies of samples of spinning solutions on a Rheotest 2 viscometer showed that for the same viscosity values determined with the falling ball method, the rheological characteristics such as the flow index, initial Newtonian viscosity, and apparent viscosity, differ. The highest strength of aramid fibres is attained in spinning from a spinning solution with the following rheological characteristics: apparent viscosity of 59.3 Pa⋅sec, initial Newtonian viscosity of 73.2 Pa⋅sec, and flow index of 0.808.     

计算机模拟醋酸纤维纺丝液的过滤过程

通过恒压过滤理论与高分子浓溶液的粘度特性对醋酸纤维纺丝液的过滤过程做了理论推导,通过计算机对纺丝液固含量、过滤温度、过滤压力等工艺参数对纺丝液过滤过程的影响做了模拟和分析。结果表明：纺鳇液圃含量升高后体系粘度会增加,同时过滤速率明显降低;升高过滤温度后纺丝液粘度有所下降,过滤速率将增大;纺丝液的过滤常数会随压差的升高而增大,过滤速率也随之所提高。     

聚酰胺酸纺丝溶液的流变性能研究

由均苯四酸二酐(PMDA)和4,4'-二氨基二苯醚(ODA)在N,N-二甲基乙酰胺(DMAc)中共聚合制得聚酰亚胺前驱体——聚酰胺酸的纺丝溶液,采用哈克流变仪研究了溶液的流变性能。结果表明:聚酰胺酸溶液属于切力变稀的非牛顿流体;溶液的表观黏度随溶液温度的升高而降低,随溶液浓度的升高或聚合物特性黏度的增大而增大。溶液温度的升高、浓度的降低或聚合物特性黏度的减小均使得聚酰胺酸溶液呈现切力变稀行为的临界剪切速率变大,使得溶液的非牛顿指数增大,同时使得溶液的结构黏度指数减小。溶液的黏流活化能随剪切速率的增加或随溶液浓度的增高而下降。     

CaCl_2配位PA6/甲酸溶液的流变性能研究

将相对黏度(ηr)为17.3～22.7的聚酰胺6(PA6)溶于甲酸中制备干法纺丝溶液,加入CaCl2作为配位剂,研究了溶液浓度、CaCl2/PA6配位比、PA6的ηr及溶液温度等对纺丝溶液流变性能的影响。结果表明:经CaCl2配位后的PA6/甲酸溶液属于假塑性流体,具有明显的非牛顿流体行为;溶液的表观黏度随PA6的ηr及溶液浓度的升高而升高,随温度升高而降低,CaCl2/PA6配位比为0.12～0.20对其影响不大;随着PA6的ηr及溶液浓度的增加,溶液的非牛顿指数减小,结构黏度指数增大;PA6的ηr约18.0,溶液中PA6质量分数控制在13%～18%,溶液可纺性较好;溶液的黏流活化能随着PA6的ηr的增加而增加。     

Effect of ammonia content on the stability of the cellulose cuprammonium complex in spinning solution

Conclusions Using a spectrophotometric method of investigation, it has been shown that in cuprammonium spinning solutions the complex compounds of copper, ammonia, and cellulose contain principally the tetraamine ion Cu(NH₃) ₄ ²⁺ .By using the molar value of the NH₃/Cu ratio in CCAC, one can calculate the free ammonia content of the spinning solution and of the precipitation bath.Translated from Khimicheskie Volokna, No. 2, pp. 30–32, March–April, 1987.     

纤维素铜氨溶液的溶解性能及流变性能

研究了纤维素在铜氨溶液中不同溶解条件下的溶解特性,以及纤维素铜氨溶液的流变性能。结果表明:当溶解温度为-10℃,Cu2+浓度为1.4 mol/L,溶解时间1 h时,纤维素在铜氨溶液中有较大的溶解度;纤维素铜氨溶液为假塑性流体,其黏度随温度的升高而降低,随纤维素含量的升高而增大,当纤维素含量较高时,其黏度随温度的变化幅度较大。     

碳纳米管对聚丙烯腈溶液流变行为的影响

将混酸处理后的多壁碳纳米管(MWNT)超声分散于含5%水的二甲基亚砜(DMSO)中,然后将其与聚丙烯腈(PAN)/DMSO(含5%水)的纺丝溶液剪切共混,制备含碳纳米管的PAN纺丝溶液。采用椎板旋转流变仪研究了PAN纺丝溶液的流变行为。结果表明,添加碳纳米管后,PAN纺丝溶液的表观粘度变大,且其对剪切速率的敏感性增强。同时,随着MWNT含量的增加,PAN纺丝溶液的非牛顿指数降低,结构粘度指数和粘流活化能增大。     

二醋酸纤维素丙酮溶液的流变性质研究

用TR - 1型气动式毛细管流变仪研究了二醋酸纤维素 (CA)丙酮溶液的流变性质 ,用X -射线衍射研究了CA的结晶结构 ,并探讨它们与流变性的关系。结果表明CA丙酮浓溶液为切力变稀的假塑性流体 ,随着溶液浓度和温度提高 ,流动曲线渐趋复杂 ;CA结晶度大小及取代均一性对流变行为有较大影响     

纤维素在NaOH/硫脲/尿素水溶液中的流变性能研究

采用新型碱复合溶剂NaOH/硫脲/尿素水溶液作为溶剂溶解纤维素,对纤维素溶液的流变性能进行探索,从而为纤维素/NaOH/硫脲/尿素溶液纺丝提供理论依据。研究结果表明,纤维素溶液表现出非牛顿流体的性质,溶液的粘流活化能随纤维素质量分数以及剪切速率的不同而有所差异,纤维素溶液的结构黏度指数随着温度的升高、纤维素质量分数的增大而增大。5~25℃是所测的纤维素溶液纺丝的适宜温度范围,随着温度的升高,凝胶点开始出现,且凝胶点随着温度的升高向高频率的方向移动。随着纤维素质量分数的增大,纤维素溶液凝胶温度降低。     

杂环芳香族聚酰胺纺丝原液孔口胀大效应的研究

采用摄影法研究了杂环芳香族聚酰胺纺丝原液的孔口胀大效应。结果表明:杂环芳香族聚酰胺纺丝原液在喷丝头挤出时会发生孔口胀大现象,在纺丝原液比浓对数黏数为4.20 dL/g,温度20～65℃,挤出压力0.25～0.45 MPa,喷丝孔长径比为1～7,滤布层数为1的条件下,纺丝原液的孔口胀大比为1.089 0～1.344 8;纺丝原液的孔口胀大比随着原液温度的上升、毛细管长径比的增大和滤布层数的增加呈逐渐减小趋势,随着聚合物相对分子质量的增大和挤出压力的增加呈逐渐增大趋势;纺丝原液的孔口胀大活化能随挤出压力的增加而增大。     

超高分子量聚丙烯腈溶液的流变性

本文研究了超高分子量聚丙烯腈—二甲基亚砜溶液的流变性能,探讨超高分子量聚丙烯腈(UHMW—PAN)的分子量、总固浓度及不同的毛细管长径比对纺丝原液的粘度、非牛顿流动指数、结构粘度指数、最大松弛时间的影响,并探讨了与原液可纺性的关系,为纺制高强高模聚丙烯腈纤维和能耐反冲洗的聚丙烯腈中空纤维膜提供了依据。     

Study on hyperbranched polyesters as rheological modifier for Spandex spinning solution

The rheological behavior of polyurethane (PU)/N,N‐dimethylformamide (DMF) spinning solutions with various contents of hyperbranched polyesters was studied using a RS150L‐controlled stress rotational rheometer. The results showed that the viscosity of the spinning solutions could be greatly reduced by adding hyperbranched polyesters even at 0.5 wt% loading. The zero‐shear viscosity of solutions with hyperbranched polyesters was much lower than that of pure PU/DMF solution, which indicated a lower degree of entanglement when solutions were in a static state. The apparent activation energy of viscous flow and the critical shear rate for shear thinning of solutions with hyperbranched polyesters were much lower than that for pure PU/DMF solution, which indicated a weaker entanglement structure formed. In addition, the effect of hyperbranched polyesters on the mechanical properties of Spandex fiber was discussed. Copyright © 2006 Society of Chemical Industry     

Some features of spinning cuprammonium fibres into precipitation baths containing calcium salts

Conclusions On the basis of data on precipitating power and the rate of dehydration of cuprammonium solutions of cellulose, the fundamental possibility has been demonstrated of spinning fibres from such solutions into precipitation baths containing calcium salts, using the technological scheme for viscose fibre manufacture.The dependence of the basic characteristics of the freshly-spun fibre on calcium salt content and temperature of the precipitation bath has been found.Moscow Textile Institute. Translated from Khimicheskie Volokna, No. 1, pp. 11–13, January–February, 1987.     

干纺氨纶纺丝原液的流变性能

利用RS150L型流变仪研究了干纺氨纶纺丝原液的流变性能。讨论了剪切速率、温度和溶液浓度对纺丝原液流变性能的影响,获得了纺丝原液在不同温度下的非牛顿指数,计算了不同剪切速率下纺丝原液的粘流活化能。进一步建立了干纺氨纶纺丝原液的零切黏度与温度、溶质的质量分数的关系式。     

共聚聚酰亚胺纺丝溶液流变性能的研究

研究了二苯酮四酸二酐-二异氰酸甲苯酯-二异氰酸二苯甲烷酯共聚聚酰亚胺(P84)的N-甲基吡咯烷酮(NMP)溶液的流变性能.结果表明:P84质黄分数为17%～21%的NMP溶液为切力变稀流体,在温度为40～60℃时,其非牛顿指数为0.80～0.98,随着P84浓度增加或温度降低,其溶液的非牛顿性增加;在低剪切速率下,P8...     

Electrospinning of aqueous lignin/poly(ethylene oxide) complexes

Microfibers of kraft lignin blended with poly(ethylene oxide) (PEO) were produced by electrospinning of the solution of lignin and high molecular weight poly(ethylene oxide) (PEO) in alkaline water. Interactions between lignin and PEO in alkaline aqueous solutions create association complexes, which increases the viscosity of the solution. The effect of polymer concentration, PEO molecular weight, and storage time of solution before spinning on the morphology of the fibers was studied. It showed that after one day the viscosity dropped and fiber diameter decreased. Results from the solutions in alkaline water and N,N‐dimethylformamide (DMF) with different polymer concentrations were compared. The 7 wt % of (Lignin/PEO: 95/5 wt/wt) in alkaline aqueous solution was successfully spun and the ratio of PEO in lignin/PEO mixture could be further reduced. In comparison, higher concentrations were needed to prepare a spinning solution in DMF and fiber diameters were in a much smaller range. The final target of spinning lignin is to produce carbonized fibers. Fibers spun from aqueous solutions had lower PEO content, which is a big advantage for the carbonization process as it reduces the challenges regarding melting of the fibers or void creation during carbonization. Furthermore, the larger diameter of these fibers inhibits disintegration of the carbonized fibers, which happens due to the mass loss during the process. © 2014 The Authors Journal of Applied Polymer Science Published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41260.     

纤维素/硅酸钠纺丝原液流变性能的研究

采用旋转流变仪对不同阻燃剂添加量的粘胶共混纺丝原液的流变性能进行了研究。结果表明,添加阻燃剂的粘胶共混原液为切力变稀型流体。随着温度升高,粘胶混合原液的粘度降低,温度在50℃以后有凝胶现象,粘度急剧增大。与普通粘胶纺丝原液相比,加入阻燃剂后的粘胶混合原液非牛顿指数n和结构粘度△η、粘流活化能△Eη等流变参数没有较大的变化,纤维素/硅酸钠纺丝原液符合纺丝要求。     

Man-made fibre production by verticaltube wet spinning

Conclusions The wet solution-spinning of polymers in tubes is highly advantageous compared with tubeless spinning. The various design solutions show that it is not possible to design a universal tube for the spinning of all types of man-made fibres by the wet method. The suitability of a given system or tube design depends on the nature and processability of the polymer, the type of yarn to be produced, and the desired physicomechanical properties of the yarn.System 1, for example, is used for spinning from solutions the density of which is lower than that of the precipitation liquor (viscose rayon, acetates, etc.). Systems 2 and 3 are used for spinning from solutions the density of which is higher than that of the precipitation liquor or for high-speed spinning. System 2 is normally used for spinning with a high jet stretch (cuprammonium rayon) and system 3 for spinning yarn below 100 tex at a speed in excess of 100 m/min (textile yarns).Translated from Khimicheskie Volokna, No. 5, pp. 35–41, September–October, 1978.     

Modification of polyacrylonitrile fibre with hydrolyzed wastes

Conclusions Principles governing the alkaline hydrolysis of wet Nitron fibre waste and their solubilities in 51.5% aqueous sodium thiocyanate solution have been studied. It has been found that the best solubility is attained at an SEC of 0.17–0.20 meq/g. The solutions obtained on addition of these wastes are characterized by reduced viscosity, better filterability, and a reduced gel-particle content.It has been found that stable spinning and preparation of fibre with better physicomechanical characteristics are achieved when 5% by wt. of the hydrolyzed products is added to the spinning solution.Translated from Khimicheskie Volokna, No. 1, pp. 10–11, January–February, 1989.     

海藻酸钠/羧甲基壳聚糖纺丝溶液的流变性能

采用RT-2000毛细管流变仪,研究了海藻酸钠(SAL)/羧甲基壳聚糖(CMCS)纺丝溶液的流变性能。结果表明:SAL/CMCS纺丝溶液是切力变稀型流体,随着剪切速率(γ)的增加,纺丝溶液的表观粘度(η_a)下降;随着纺丝液中CMCS含量的增加,SAL/CMCS纺丝溶液的η_a和结构粘度指数(△η)下降,非牛顿指数(n)增大;随着纺丝液温度的升高,SAL/CMCS纺丝溶液的η_a和△η下降,n增大。纺丝过程中应控制SAL/CMCS纺丝溶液的温度为35℃,纺丝溶液中CMCS质量分数为15%较适宜。