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。     

不同聚乳酸切片的流变性能比较及其对熔融纺丝性能的影响研究

利用毛细管流变仪对四种不同聚乳酸切片的流变行为进行了对比分析,并探讨了流变性能差异对熔融纺丝性能的影响。结果表明:四种聚乳酸熔体均呈现剪切变稀现象,具有非牛顿流体的流动特征;随着温度升高,聚乳酸熔体的非牛顿指数n增大;四种聚乳酸熔体的粘流活化能E_η较小,粘度随温度的变化小,有利于纺丝成型;四种聚乳酸熔体的结构粘度指数△η介于0.8~1.4,可纺性和稳定性较好。     

高温法二醋片可纺性表征方法初探

本文利用毛细管流变仪研究几种醋片丙酮纺丝原液的流变性。分析了粘流活化能与可纺性的关系。认为ΔＥη可作ＣＡ－丙酮纺丝原液可纺性的表征参数。ΔＥη越小，可纺性越好。ΔＥη大于８０ＫＪ。ｍｏｌ＾－１时，可纺性差。     

聚丙烯腈分子量及纺丝溶液流变性研究

分别用高温凝胶渗透色谱PL-GPC220和安东帕MCR302型高级旋转流变仪测定聚丙烯腈(PAN)的分子量及纺丝溶液的流动曲线,讨论纺丝液流变性能的影响因素。结果表明,PAN的分子量随着引发剂浓度的增加而减小,分子量分布逐渐变窄。60℃下,聚丙烯腈/二甲基亚砜纺丝液属于"剪切变稀"的非牛顿型流体,温度升高,流动曲线lgηa~lgγ整体下移、非牛顿指数n增大、结构粘度指数Δη减小;增大剪切速率,粘流活化能Eη减小;增大分子量,非牛顿指数n减小、结构粘度指数Δη增大。     

PAN基碳纤维原丝用纺丝溶液的流变性质

为制备适于干 -喷湿纺用PAN(polyacrylonitrile)纺丝溶液 ,选用了较高粘均相对分子质量的PAN ,通过测定纺丝溶液的回转粘度 ,对其流变性能进行了较为详尽的研究。研究结果表明 :粘均相对分子质量为近 2 0万的PAN溶液为切力变稀型流体 ,具非牛顿性。在40～ 80℃的温度范围内 ,浓度为 18%～ 2 0 %的纺丝溶液的临界切变速率为 10 0 9～ 10 1 7。提高纺丝溶液的浓度可使溶液的粘流活化能 (Eη)及结构粘度指数 (Δη)增大、非牛顿指数 (n)减小 ;溶液温度升高则会导致n的增大和Δη的减小     

高相对分子质量PAN纺丝溶液的流变性质

研究了聚丙烯腈 (PAN )纺丝溶液的浓度、温度及聚合物相对分子质量对纺丝溶液的 lgηa ～lgγ流动曲线、粘流活化能、非牛顿指数和结构粘度指数的影响。结果表明 :高相对分子质量聚丙烯腈纺丝溶液具有明显的非牛顿性 ,结构粘度指数随纺丝溶液浓度的升高 ,PAN相对分子质量的增大而增大 ,随纺丝溶液温度的升高、聚合物相对分子质量和浓度的降低而减小。纺制高性能的高相对分子质量PA N纤维宜采用较低的溶液浓度和较高的纺丝温度。     

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。     

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。     

改性PBT熔体流变性能及其对可纺性影响研究

利用毛细管流变对不同组成的改性聚对苯二甲酸丁二醇酯(PBT)树脂进行了流变行为研究,探讨了流变性能差异对可纺性的影响。结果表明:不同组成的改性PBT熔体均呈现剪切变稀现象,具有非牛顿流体的流动特征;随着温度升高,改性PBT熔体的非牛顿指数n增大;改性PBT熔体的粘流活化能相对较小,对温度敏感度低,有利于纺丝成型;改性PBT熔体的结构黏度指数介于0.7～1.0,预期其可纺性和稳定性较好。     

UHMW—PAN中空纤维膜的研制及应用Ⅲ.温度对UHMW—PAN／DMSO溶液流变 …

在前文＾「１～３」的基础上，研究了温度对超高一聚丙烯腈／二甲基亚砜溶液的零切粘度、流动曲线、非牛顿指数、最大松弛时间、结构粘度指数的影响，探讨了它们与溶液流动性、可纺性和挤出过程稳定性的关系。发现与常规分子量聚丙烯腈／二甲基亚砜溶液相比，其非牛顿指数和粘流活化能较小；而最大松弛时间却高出约三个数量级，因此当原液温度低于１３０℃时，流动曲线上不出现第一牛顿区。确定了溶液流动性、可纺性和挤出过程稳定性     

低温溶液缩聚制备芳香族聚砜酰胺的研究

采用低温溶液缩聚的方法,将对位二氨基二苯砜(4,4′-DDS)、间位二氨基二苯砜(3,3′-DDS)和对苯二甲酰氯(TPC)在二甲基乙酰胺(DMAc)中进行缩聚,制得较高相对分子质量的芳香族聚砜酰胺树脂,并研究了各反应因素对聚合物相对分子质量的影响。结果表明:浆液浓度为13%,反应初始温度为10℃,TPC/DDS摩尔比为1.001～1.003,反应时间50～60min时,可获得理想的聚合物。     

含中草药成分的纤维制备与性能研究Ⅰ.柿叶/纤维素共混纤维的制备及力学性能

以二甲基亚砜(DMSO)／多聚甲醛(PF)为溶剂,添加柿叶活性成分,应用湿法纺丝技术,制得含柿叶提取物的再生纤维素纤维。研究了纺丝原液浓度、凝固浴温度、柿叶添加量对共混纤维的力学性能的影响。结果表明,当纺丝原液质量分数在10％-12％,凝固浴温度在40-50℃,柿叶提取物质量分数在5％左右,纤维具有较好的可纺性,柿叶的添加使共混纤维的结晶度、取向度、强度均有一定程度的下降。DSC测试表明柿叶与纤维素之间有较好的相容性。     

Shear flow behaviors of poly(p‐phenylene benzobisoxazole) spinning dope

In this study, the shear flow properties of Poly(p‐phenylene benzobisoxazole) (PBO)/poly(phosphoric acid) (PPA) spinning dope were studied by means of capillary rheometer. The effect of shear stress, temperature, PBO concentration, and PBO molecular weight on the apparent viscosity of PBO/PPA dope was discussed. The results showed that the apparent viscosity of the dope decreased with the increase of the shear stress and the temperature. The flow behavior index increased with the increase of temperature, which indicated that the non‐Newtonian behavior of the dope became weaker at high temperature. Moreover, it was also found that at high shear stress, the apparent viscosity of the dope was insensitive to the temperature, PBO molecular weight, and PBO concentration. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

影响干法氨纶中残留溶剂含量的因素

考察了甬道温度、原液质量分数、纺丝速度、单丝纤度、喷丝孔形状等对氨纶丝残留溶剂含量的影响。结果表明:在甬道长度恒定的情况下,甬道温度的增加、纺丝速度的降低以及单丝纤度的减少都有利于降低氨纶丝中残留溶剂的含量;原液质量分数对残留溶剂含量的影响则比较复杂,原液质量分数35%时,残留溶剂含量随原液质量分数的升高而降低,而原液质量分数35%时,残留溶剂的含量随浓度的升高而升高;另外,选择合适形状的喷丝板也有利于降低残留溶剂的含量。     

Hemodialysis membrane prepared from cellulose/N‐methylmorpholine‐N‐oxide solution. I. Effect of membrane preparation conditions on its permeation characteristics

Flat hemodialysis membranes were prepared from cellulose/N‐methylmorpholine‐N‐oxide (NMMO) solutions (dope) with different cellulose concentrations (6–8 wt %) by using a phase‐inversion method. The coagulant used was NMMO aqueous solution, of which the NMMO concentration and its temperature were varied in the range of 0 to 50 wt % and 5 to 60°C, respectively. The effects of these preparation conditions on the permeation characteristics, the ultrafiltration rate (UFR) of pure water, and sieving coefficient (SC) of dextran, were investigated. The decrease in cellulose concentration of the dope and the increases in both temperature and NMMO concentration of the coagulant gave a membrane with high UFR. Concerning the SC, the increase of the cellulose concentration and the decreases in both temperature and NMMO concentration gave a good result. Consequently, the membrane having the preferable UFR and SC as a hemodialysis membrane was obtained when the 8 wt % cellulose dope was coagulated in water at 5°C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2302–2307, 2002     

氨纶纺丝原液流变性能的研究

采用简易式毛细管流变仪、高聚物浓溶液动态粘弹仪和显微摄影技术,在模拟实际纺丝工艺条件下,测定了氨纶(PU)原液的稳态和动态流动曲线、孔口膨化比,重点研究了PU原液温度对其粘弹性的影响。研究结果证明,PU原液为切力变稀流体,结构粘度指数(Δη)、剪切弹性模量(G)均随温度升高而下降,在30—50℃范围内,Δη与G的变化甚微,这表明氨纶可在室温下纺丝,增加原液温度不仅使可纺性更佳,且有利于提高纺速,从而制得细旦氨纶。     

湿纺工艺纺制PAN中空纤维成形机理研究

利用C型喷丝板进行挤出凝固,采用湿法纺丝工艺制备聚丙烯腈(PAN)中空纤维,从PAN/二甲基亚砜(DMSO)纺丝原液的流变性能和凝固过程的相分离两个方面探讨了PAN中空纤维的成形机理。结果表明:纺丝液随剪切速率(γ)的增加逐渐发生由粘性向弹性的转变是挤出胀大的主要原因,其粘弹转变点随着温度的升高而向高γ移动,在60℃下的纺丝液弧片接触成孔的理论临界γ为212 s~(-1);纺丝液在凝固浴中表层成膜是PAN-DMSO-H_2O三元体系相分离的结果,纺丝液细流表面成膜速度是影响孔结构闭合的重要因素,可以通过凝固浴浓度和凝固浴调节剂来控制。     

Hollow Fiber Ultrafiltration Membranes from Poly(Vinyl Chloride): Preparation,Morphologies, and Properties

Hollow fiber poly(vinyl chloride) membranes were prepared by using the dry/wet spinning method. Cross-section, internal, and external surfaces of the hollow fibers structure were studied by SEM. The pore size and pore size distribution of the hollow fibers were measured by a PMI capillary flow porometer. UF experiments of pure water and aqueous solution of PVP K-90 were carried out. The effect of the PVC concentration on the hollow fibers mechanical properties was also investigated. It was found that the PVC fibers cross-sectional structure was affected by the polymer concentration in the dope solution. In particular, reduction of macrovoids size was observed when increasing PVC concentration from 15 to 19 wt%. The pore size distribution of the PVC hollow fibers was controlled by adjusting the PVC concentration. Indeed, an increase of PVC concentration up to 19 wt% leads to fibers with sharp pore size distribution (the 99% of pores is about 0.15 µm).The pure water permeation flux decreased from 162 to 128 (l/m² · h · bar), while the solute separation performance increased from 82 to 97.5%, when increasing the PVC concentration. The elongation at break, the tensile strength, and the Young's modulus of the PVC hollow fibers were improved with PVC concentration in dope solution.     

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。     

Two‐dimensional simulation of hollow fiber membrane fabricated by phase inversion method

In the steady fabricating process, two‐dimensional hollow fiber membrane near the spinneret was numerically simulated using the finite element method (FEM). The unknown positions of free surface and moving interface were calculated simultaneously by the velocity and pressure fields. The effects of seven relevant parameters, i.e., inertia term, gravity term, dope flow rate, bore flow rate, dope viscosity, tensile force, end velocity and non‐Newtonian on the velocity and diameter profile were studied. On the basis of the simulated results, the inertia term in hollow fiber‐spinning process was safely neglected in low speed, while the effect of gravity was not be neglected. Besides, the outer diameter of the fibers increased with an increase of dope flow rate and bore flow rate; Large tensile force or large end velocity could cause large deformation in the air gap; larger viscous dope solution tended to make less deformation in the air gap. It was found that an increase of the dope flow rate at small dope flow rate resulted in an increase of the inner diameter, while at large dope flow rate, it decreased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2067–2074, 2006