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。     

抗盐聚合物流变性影响因素研究

通过实验研究聚合物浓度、水矿化度、温度,聚合物分子量、剪切速率等对抗盐聚合物流变性的影响,总结了它们的影响规律。实验结果表明:在低剪切速率下抗盐聚合物较稳定,有利于驱油;抗盐聚合物受水矿化度影响不大;随着温度的升高,抗盐聚合物的动力黏度变化不大;对于抗盐聚合物,在任何剪切速率下,分子量大的动力黏度值也大;在低剪切速率(81 s~(-1))下,抗盐聚合物溶液的动力黏度与浓度无线性关系;当较高剪切速率(81 s~(-1))下,动力黏度与浓度成线性关系。通过抗盐聚合物与普通阴离子聚合物的对比研究,得出了抗盐聚合物更适用于驱油的优点。     

PEN和PET的流变性能

聚2,6-萘二甲酸乙二醇酯(PEN)是一种结构上与PET非常相近的新型聚酯,近年来逐渐成为研究的热点.利用哈克流变仪对PET和PEN在不同温度及剪切速率下的流变性能进行了研究.流变行为研究表明:PEN的剪切黏度随剪切速度的增加而减小,属于典型的非牛顿流体;从流变曲线上来看,随着剪切速率的改变,PEN的剪切黏度的变化要小;而黏流活化能则表明:PEN剪切黏度的变化对温度的变化更敏感,这就意味着PEN对加工工艺具有更高的要求.     

磺化木质素水溶液的流变行为

采用旋转黏度仪研究三种磺化木质素(钙离子、镁离子和钠离子)的水溶液流变行为,发现磺化木质素(LGS)水溶液的流变行为随着剪切速率的变化显示出不同的特征,其中存在一个临界剪切速率(γc),将剪切速率分为低和高两个区域。γc与相对分子质量和温度(t)都有关,其γc―t呈现非常好的线性关系,从而可以外推得到一个特性剪切速率[γ]。而由于[γ]不仅是一个唯一值,而且正比于特性黏度[η],所以可能是一个新的高分子流变性能的参数,可以用来预测高分子的流变性能,或根据高分子的相对分子质量预测其流变行为。通过研究LGS水溶液的浓度对流变性能的影响发现,低浓度时具有切力变稀和增稠两种不同的流变行为,而高浓度时仅有单一的切力变稀或增稠行为。     

含氯对位芳香族聚酰胺溶液流变特性研究

采用ARES-RFS流变仪研究了低温缩聚法制备的含氯对位芳香族聚酰胺(Cl-PPTA)溶液的流变特性,讨论了Cl-PPTA浓度、Cl-PPTA相对分子质量及温度对溶液流变特性的影响,并运用Cox-Merz关系式研究了稳态剪切粘度(ηa)和动态复数黏度(η*)的相互关系。结果表明:Cl-PPTA溶液为切力变稀的非牛顿流体;随着溶液中Cl-PPTA浓度和相对分子质量的增加,温度的降低,溶液的非牛顿性增加;Cl-PPTA浓度越高,相对分子质量越大,则溶液黏流活化能(△Eη)越大;随着Cl-PPTA浓度和相对分子质量增加,相应的储能模量(G')、损耗模量(G″)和η*越大;Cl-PPTA溶液浓度或温度增大时,在一定的剪切速率(γ)和角频率(ω)范围内,ηa和η*两曲线出现了重叠区域,仅在较高或较低的γ和ω时,两曲线出现偏离,Cl-PPTA溶液的流变特性符合Cox-Merz关系式。     

聚丙烯腈/离子液体溶液流变性能的研究

采用应力流变仪对聚丙烯腈/1-丁基-3-甲基咪唑氯化物(PAN/[BMIM]Cl)溶液体系的稳态和动态流变性能进行了研究,讨论了PAN相对分子质量(Mη)对溶液稳态和动态流变性能的影响。结果表明:PAN/[BMIM]Cl溶液在低剪切速率区表现出牛顿流体特征,在高剪切速率区随着剪切速率的增大粘度降低,表现为切力变稀流体;溶液的粘度大于常规溶剂体系,随着PAN的Mη增大,PAN/[BMIM]Cl溶液表观粘度明显增大,非牛顿指数减小,粘流活化能增大;溶液的损耗模量和储能模量越大,溶液更容易表现出弹性效应。     

渤海注聚油田配注系统模拟仿真方法研究

海上油田聚驱技术现场驱油效果显著,有逐渐扩大应用的趋势.聚合物溶液的高黏度特性是聚驱增油机理的核心.然而,聚合物溶液在流经配注流程、近井地带进入地层的过程中,却发生不同程度的降解,严重影响驱油效果;同时,聚合物溶液不同于水为非牛顿流体,其黏度受剪切速率、分子量以及矿化度等多重因素的影响,所以聚合物溶液黏度会出现较复杂变化,其计算精度直接影响着井口最大注入压力计算结果的准确性,进而影响安全性或注入性.因此,对聚合物溶液注入过程的精确模拟是十分必要的,然而截止目前,该方面研究却较少.本文在物模实验与矿场测试数据相验证的基础上,结合fluent软件形成了一套注聚井配注过程数值模拟仿真方法,以期能为注聚管柱、流动通道、注入速率的优选及工艺改进,注聚井最大井口注入压力计算,油藏方案设计等提供参考.利用该方法对聚合物溶液在S油田F06井Id段的黏度分布、速率分布、压力计算、沿程摩阻以及流场进行数值模拟,得出S油田母液地面粘损70％～80％左右,F06井Id段仍有2MPa的加压余量,可提高配注量约30％,可显著提高驱油效果等结论.     

基于流变特性探讨聚芳砜酰胺纺丝液的稳定性

利用旋转流变仪研究了聚芳砜酰胺(PSA)纺丝液的稳态和动态流变行为,结果表明:以二甲基乙酰胺(DMAc)为溶剂的聚芳砜酰胺溶液表现出典型的聚合物浓溶液流变特性,在低剪切速率区表现为牛顿流体特性,而随着剪切速率的增大,呈现出切力变稀行为,纺丝液的零切黏度、松弛时间随PSA特性黏度的增大而增大,非牛顿特性增强;证明了PSA纺丝溶液在测试温度范围内处于均质溶液状态,在进一步的动态温度扫描分析中,没有发现溶液的凝胶化转变现象,说明在试验温度范围内,PSA纺丝液处于均质稳定状态。     

低浓度淀粉溶液的流变性及其影响因素分析

文章研究了低浓度淀粉溶液的流变性能及其影响因素,结果发现：低浓度淀粉溶液呈现牛顿流体的性质,随着浓度、温度的升高,黏度逐渐升高;不抗酸抗碱;随着搅拌时间和剪切速率的增大,黏度逐渐降低的.     

基于注塑机的聚合物流变特性在线测试

提出一种基于注塑机的聚合物流变性能在线测试新方法,在实际成型工艺条件下测得LDPE和PP的流变特性数据.利用Cross-WLF黏度模型对实验结果进行拟合,测试得到的黏度曲线与Molflow软件材料数据库结果一致.同时导出不同工艺条件下非牛顿指数,n和零剪切黏度η0的计算方法.     

Viscosity of polystyrene solutions expanded with carbon dioxide

The viscosity of solutions of polystyrene (PS) in decahydronaphthalene (DHN) was measured in the presence of carbon dioxide (CO₂) with a moving‐piston viscometer. The effects of the CO₂ pressure (0–21 MPa), polymer concentration (1–15 wt %), temperature (306–423 K), and polymer molecular weight (126 and 412 kDa) on the viscosity were investigated. In the absence of CO₂, the increase in the viscosity with increasing polymer concentration was approximately exponential in concentration and was well described by the Martin equation. All the data fell on a single line when the relative viscosity was plotted against cM^0.50 (where c is the concentration of the polymer in solution and M is the molecular weight of the polymer). The viscosity of the polymer solution decreased with increasing CO₂ pressure under otherwise constant conditions. For a given CO₂ pressure, the viscosity reduction was greatest when the relative viscosity was high in the absence of CO₂, that is, for high‐molecular‐weight polymer, high polymer concentrations, and low temperatures. Reductions in the relative viscosity of almost 2 orders of magnitude were observed in some cases. The viscosity of solutions of PS in DHN also was measured in the presence of sulfur hexafluoride (SF₆). At a given pressure, SF₆ was about as effective as CO₂ in reducing the solution viscosity. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 540–549, 2006     

水解聚丙烯酰胺盐水溶液表观粘度的数学模拟(Ⅲ)——表观粘度与剪切速率的通用关系式

通过对水解聚丙烯酰胺盐水溶液的流动曲线的分析,提出了两点假设.据此分别建立了Meter-Bird式常数γ_(1/2)和P_α与零剪切粘度η_0间的经验式,及表观粘度η_α和剪切速率γ间的通用 Meter-Bird式.用此方程式与本文(Ⅰ)报通用 MHS方程式和(Ⅱ)报式(4) 联用,模拟水解聚丙烯酰胺盐水溶液的表观粘度,取得了较好的结果.     

Viscous flow in aqueous solution of quaternary ammonium salts: high concentration range

By introducing the condition that the viscosity of solutions η → η₀, the viscosity of the solvent as the concentration of the salt N → 0, we have recast Angell's equation in the following form, ln η_rel = kN/[N_o(N_o  N)]. This equation has been found to represent satisfactorily the viscosity behaviour of quaternary ammonium halides in aqueous solution up to high concentration and the values of N₀, the hypothetical concentration at which the solution becomes a glass, agree with those obtained from Angell's equation. The relationship with Vand's equation of fluidity is also discussed.     

乙酸甲酯水解催化精馏过程催化剂包内的传质模型(Ⅰ)数学模型

分析了催化精馏过程催化剂包内的传质 ,提出催化剂颗粒的不完全润湿和包内反应物浓度的不均匀是造成催化剂效率下降的原因 .催化剂包总效率因子是表征催化剂不完全润湿程度的表面润湿率 η_s 和表征由于包内反应物浓度的不均造成催化剂效率下降的效率因子 η_c 的乘积 .建立了一个二维传质模型 ,给出了 η_c 的计算式 .结果表明 ,η_c 不仅与反映扩散速率的Thiele模数有关 ,还与反映包内液体轴向流速的参数Ψ或γ有关 .由于催化剂包内存在液体的轴向流动 ,大大减小了扩散传质速率对催化剂包效率因子的影响     

［bmim］Cl-CH3OH作为吸收式制冷工质对的潜能分析

提出将［bmim］Cl/CH₃OH应用为吸收式制冷工质对,并从多角度对其应用潜能进行分析。采用静态法饱和蒸气压测定装置、DSC、乌氏黏度计和比重瓶等测定了293.15～353.15 K温度范围内［bmim］Cl/CH₃OH溶液的汽液平衡、比热容、黏度和密度,拟合得到溶液汽液平衡的NRTL模型参数以及比热容、黏度、密度随浓度和温度的经验关联式。结果表明：［bmim］Cl/CH₃OH溶液的性质满足理想吸收式制冷工质对的要求,在吸收式制冷中有较大的应用潜能。     

Comparative studies of rheological properties of polyacrylamide and partially hydrolyzed polyacrylamide solutions

The present work is concerned with experimental results of rheological characteristics of polyacrylamide (PAM) and of partially hydrolyzed polyacrylamide (HPAM) (degree of hydrolysis up to 80%) in aqueous and aqueous/sodium chloride solutions with changing experimental conditions such as polymer concentration, temperature, solvent quality, and shear rate applied. It has been observed that the all‐aqueous and aqueous/NaCl solution of PAM and of HPAM exhibited the non‐Newtonian behavior with shear‐thinning and shear‐thickening areas. The onset of shear‐thickening at depends mainly on the degree of HPAM hydrolysis, as well as on solution concentration, temperature, solvent quality, and polymer molecular weight. Rheological parameters from power law (Ostwald de Waele model) and activation energy of viscous flow (E_a) are determined and discussed. The changes in apparent shear viscosity during aging of solutions of PAM and HPAM are also described. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2235–2241, 2007     

Dipolar polymeric compounds and their properties in the aqueous medium

Reactions between poly(4-vinylpyridine) and acrylic acid as well as poly(vinylimidazole) and the same acid led to polymers containing carboxybetaine repeating units with a percentage higher than 90%. Chemical structures and compositions of chemically modified polymers were established from their ¹H NMR and IR spectra. The solution properties of the two poly(carboxybetaines) were analyzed by potentiometric titrations and viscometric measurements. Deionized water as well as CaCl₂ and NaCl aqueous solutions of different concentrations were used as solvents. From potentiometric titrations with 0.5 M HCl, the apparent pK_a values were determined using Henderson–Hasselbach equation. These values are strongly depended of the solvent nature. Thus, both poly(carboxybetaines) have the lowest pK_a values when deionized water was used as solvent. Therefore, the lowest binding ability of the H⁺ by COO⁻ groups occurs in this solvent.The viscometric measurements revealed that reduced viscosity values are non-responsive towards the polymer solution concentrations irrespective of the used solvent (i.e., deionized water or NaCl and CaCl₂ aqueous solutions). Therefore, the behaviour of these carboxybetaine macromolecules in the above-mentioned solvents is that of hung up hard spheres. Consequently, the intrinsic viscosity values were calculated according to the Einstein–Simha equation applicable for such systems. The [η] versus salt solution concentration plots show a decreasing part in the concentration range from 0 to 0.05 M that is followed by a slow [η] increasing.In 0.5 M HCl both poly(carboxybetaines) exhibit the viscometric polyelectrolyte behaviours because of their shift to the corresponding cationic polyelectrolytes.     

缔合聚合物近井地带剪切模拟实验研究

通过近井地带剪切模拟装置对缔合聚合物溶液进行多次重复高速渗流剪切,研究近井地带的剪切作用对缔合聚合物溶液性能影响。结果表明,聚合物溶液高速流经近井地带各段后(包括射孔孔眼段、射孔压实带和近井地带地层),其溶液表观粘度大幅度下降;随着剪切次数的增加,聚合物溶液粘度下降趋势减缓;剪切作用造成缔合聚合物溶液结构破坏,使聚合物分子间的堆积程度降低,进一步消弱缔合聚合物溶液网络结构的强度,致使溶液表观粘度出现大幅度下降。     

Influence of polymerization conditions on the viscosity of polyacrylamide via experimental design

Polyacrylamide was synthesized by a free‐radical inverse emulsion technique and optimized via statistical experimental design, with the objective of developing a polymer with a high viscosity within this synthesis technique. The factors considered to affect the response variable, the viscosity of the polymer, were initiator (K₂S₂O₈) concentration (c), reaction temperature (T), stirring rate (r), and initiator addition method (s, batch or dropwise). An experimental design of the four factors at two levels (2⁴) was carried out to study the effect of these process variables on the viscosity of the polymer. The results show that the main factor having an effect on the viscosity was T, with smaller contributions from r and cs. The optimum combination of values for the factors yielding maximum viscosity was T = 65°C, c = 1 mM, r = 230 rpm, and s = dropwise addition. A close fit was obtained between the experimental and predicted values of the viscosity of the polymer solution. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5719–5724, 2006     

Solution properties of a hyamine based on N,N‐dimethyl diallyl ammonium chloride–acrylamide copolymer

A hyamine based on N,N‐dimethyl diallyl ammonium chloride–acrylamide copolymer was successfully synthesized in this study. Solution properties of this hyamine including electrical conductivity and viscosity behavior were studied in detail, and effects of temperature and counter ion concentration on electrical conductivity of the solution were also discussed. It was found that a solution of hyamine in water showed a typical viscosity behavior of polyelectrolytes, which followed the Fuoss equation. With the increase of ion radius (cationic ion or anionic ion), or with the increase of salt concentration, the shrinkage degree of the polymer chain increased, with a concomitant decrease in reduced viscosity and intrinsic viscosity and an increase of Huggins constant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 765–771, 2003