聚丙烯酰胺水溶液的流变特性

通过测定聚丙烯酰胺(PAM)水溶液不同状态下的表观黏度,研究了质量浓度、剪切速率和温度对PAM溶液流变特性的影响。结果表明,在浓度范围1.0～4.0 g/L时,PAM溶液表观黏度随浓度的增加呈线性递增。在浓度范围2.0～4.0 g/L时,PAM溶液表现为假塑性流体特性,其表观黏度随剪切速率的升高而降低,且两者的对数值呈线性关系,非牛顿指数n随稠度系数K的增加而降低;溶液表观黏度随温度的升高而降低,其黏流活化能约为10 kJ/mol。PAM溶液表现为明显的正触变性。     

Functionalization of fullerene nanowhiskers using pyrenebutanoic acid, succinimidyl ester in an aqueous solution

The functionalization of fullerene nanowhiskers was accomplished by non-covalent π-π interaction using pyrenebutanoic acid, succinimidyl ester to immobilize target molecules on the nanowhiskers. Fourier-transform infrared spectroscopy and fluorescence microscopy proved that the fullerene nanowhiskers were functionalized without damaging the nanostructure.     

Viscoelastic properties of aqueous solution of methylcellulose

The viscoelastic properties of aqueous solution of methylcellulose were investigated using three types of rheometers, which enabled us to cover more than 8 decades of frequency range. At first, the entanglement density X/q at various temperatures was estimated by comparing G′, and G″ curves and relaxation spectra experimentally obtained with those calculated from Hayashi's theory. At lower temperatures, the concentration dependence of X/q was small as observed for polyelectrolytes, but increased at higher temperatures. The same tendency was observed in the concentration dependence of the entanglement function GeN. It is supposed that water molecules adsorbed on methylcellulose and depressing the entanglement formation dissociate with increasing temperature. The relaxation mechanism was then examined from the concentration dependences of G′, η′, and ηo at various temperatures and frequencies. It is concluded that the structural networks in a solution become closer with increasing temperature, and the corresponding viscoelastic mechanism varies from the intermolecular interaction such as entanglements to the intramolecular motion with increasing frequency.     

Flow properties of aqueous solution of methylcellulose

Flow properties of aqueous solution of methylcellulose, especially nonlinear viscoelasticity, were investigated. The peculiar flow properties of the aqueous solution of methylcellulose were compared with the existing theories of non-Newtonian viscosity of concentrated polymer solutions and the experimental results obtained for the aqueous solution of sodium alginate which behaves as polyelectrolyte in solution. The characteristic time for the formation of entanglement couplings between molecular chains was mainly examined. To investigate the elastic behavior under steady-shear flow, normal stress difference was measured with a coaxial cylinder apparatus, and extinction angles were determined with a flow birefringence apparatus. The values of normal stress difference obtained by the mechanical and the optical methods coincided with each other. For the aqueous solution of methylcellulose as reported for solutions of nonpolar polymers, the relation between normal stress difference and shear stress was represented by a single curve irrespective of temperature and concentration. Non-Hooken behavior was observed for the relation between recoverable shear and shear stress and attributed to the strong intermolecular interactions and the stretching-out effect of structural networks.     

Synthesis and aqueous solution properties of hydrophobically modified polyacrylamide

Hydrophobically modified polyacrylamide (HMPAM) is synthesized by a free radical micellar polymerization method with low amounts of anionic long‐chain alkyl, sodium 9‐(and 10)‐acrylamidostearate (NaAAS), which is derived from a renewable resource material, oleic acid. In this progress, the molar ratio of Sodium dodecyl sulfate (SDS) to NaAAS is adjusted, so polymers with different lengths of the hydrophobic blocks (NH = 3 and NH = 6) are obtained. The copolymers are characterized by ¹H NMR, and the polymer weight and polydispersity are determined by gel permeation chromatography. The solution behaviors of the copolymers are studied as functions of concentrations, pH, and added electrolytes by steady‐flow and oscillatory experiments. The viscosities of these HMPAMs increase enormously above the critical concentration (c*). The sample with longer hydrophobic blocks exhibits better thickening effect. The rheological behaviors of aqueous solutions of HMPAMs are also investigated at different pH and brine environments. Low pH or the presence of brine promotes the intramolecular associating of hydrophobes for the both copolymers in semidilute solutions. The introduction of ionizable carboxylic group on the long hydrophobic side chain significantly influences the aggregation behaviors of the copolymers, leading to unique solution behaviors of the poly(AAm/NaAAS) copolymers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40754.     

Effect of added salt on properties of aqueous SMP solution

Sulfomethylated phenolic resin (SMP) is a drilling mud additive having good fluid loss and dispersion characters and may be resistant to the action of high temperature and high salt frequently encountered in well drilling, especially in deep wells. SMP is one kind of polyelectrolyte. There are dissociable groups (? CH₂SO^?₃Na⁺) along the chain of SMP. The conformations and properties of SMP in solution are affected greatly due to electrostatic attraction and repulsion. From the experimental results of viscosities and fluorescence spectra of polyelectrolyte SMP in pure water and aqueous solutions containing added salt, the effects of added salt on molecular conformations of SMP in aqueous solution and properties of reducing fluid loss of water base drilling mud are discussed. © 1995 John Wiley & Sons, Inc.     

新型聚合物表面活性剂的水溶液性质研究

采用布氏粘度计测定大庆油田用的4种聚表剂的水溶液粘度及粘度稳定性,结构表明,4种聚表剂溶液的粘度随着聚表剂浓度的增加而增大;随着剪切速率的增大先快速降低,随后变化较小,且在模拟污水中,聚表剂溶液的粘度降低较快;聚表剂溶液的粘度随着时间的延长而降低,在模拟污水,聚表剂溶液的粘度相对稳定。     

Synthesis and aqueous solution properties of novel thermosensitive polyacrylamide derivatives

A series of novel thermosensitive polymers were synthesized with acrylamide and thermosensitive macromonomers by radical polymerization in water solution. The structures of the copolymers were characterized by ¹H‐NMR. The effects of the polymer concentration, NaCl concentration, shear rate, and chemical structure on the thermothickening behavior of the polymer solution were investigated by advanced rheometry. The luminous transmittance of the solution with various polymer concentrations was tested by visible spectrometry. The results show that the thermothickening behavior was due to the phase separation of the polymer solution or intramolecular repulsions between the hydrophobic side chains and hydrophilic backbone at high temperatures. Finally, the thermothickening properties of the novel copolymer were studied under conditions simulating an underground oil reservoir. This novel copolymer is expected to be used as an oil‐displacing agent to enhance oil recovery in the future. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 766‐775, 2013     

沸石材料的改性及其对水体污染物的吸附性能

吸附法以其选择性强、操作简易、二次污染少等优势逐步成为污水处理的重要方法。天然沸石材料具有孔腔结构丰富、吸附成本低廉以及吸附性能高等优势,但存在选择吸附性差、与水相分离困难、再生成本偏高等问题。通过改性,可以为沸石吸附剂对阴离子污染物的吸附提供更多吸附活性位点。本文基于沸石材料改性制备的国内外最新研究进展,总结了不同改性材料制备复合吸附材料的研究工作,重点介绍了沸石材料改性方法及其应用,进一步回顾了改性沸石材料对水中污染物的吸附性能和影响因素。通过改性提高沸石材料的选择吸附性能及吸附后的绿色再生将是推动沸石吸附材料规模化应用发展的核心。     

Rheological properties of hydroxypropyl- and sodium carboxymethyl-substituted guar gums in aqueous solution

The aqueous solutions of guar gum and its hydroxypropyl (HP) and sodium carboxymethyl (sod CM) derivatives are pseudoplastic, and the transition from Newtonian to pseudoplastic occurs in the low-shear-rate range at the concentrations of interest to industries. The flow properties of these polysaccharide solutions were studied in the range of low to moderately high shear rates, using a very simple technique and instrument. The flow of these polysaccharide solutions can be described by equation of state based on Cross model, and the basic rheological parameters, like zero shear rate viscosity (η₀), elasticity modulus (G₀), and relaxation time (γ₀), were calculated from simple and established relations. Master viscosity curves indicate that the molecular weight distribution of native guar gum has not been changed by derivatization. The effect of concentration and temperature on rheological parameters (η₀ and γ₀) has been studied, and the relations among these were established by simple equations.     

Study of the rheological properties and solution microstructure of progressively cross-linked aqueous gels

A stepwise cross-linking polyacrylamide hydrogel was prepared using the laboratory homemade stepwise crosslinker PVC-PP-Cr and partially hydrolyzed polyacrylamide. The microstructure was investigated by using the scanning electron microscope and dynamic light scattering. The results show that the system has a controllable cross-linking time of 4 ~ 6 h, good heat resistance, and maximum gel strength of >300,000 mPa.S. In terms of viscoelastic behavior, a stepwise cross-linking process between crosslinker and hydrolyzed polyacrylamide (HPAM) is presented, and the viscoelasticity is increased step by step. During the stepwise cross-linking process, the dendritic structure, network structure and lamellar structure to a stable spatial network structure is obtained. Here, the cross-linked structure between polymer molecular chains is formed after addition of the crosslinker, which increases the steric hindrance of macromolecular chains and further enhances the stability of the system. With the gradual release of chromium ions from the PVC-PP-Cr stepwise crosslinker, the gel system is formed continuously. When intermolecular friction stopped increasing, intermolecular entanglement and interaction are enhanced, and elasticity is also increased.     

DMSO溶液玻璃化过程氢键生命期特性

引言 许多液体被冷却到某个特征温度时,容易结晶,这个温度是熔融温度.这个过程中,首先形成晶核,然后晶体生长,无序的分子排列于是变得高度有序.但是只要超过一定速度降温到另外一个特征温度,液体就能避免结晶,这个特征温度被称为玻璃化温度.随着液体的温度被降到玻璃化温度以下,液体分子还是保留着无序的状态.     

Viscoelastic properties of dilute aqueous solution of methylcellulose at ultrasonic frequencies

The viscoelastic properties of dilute aqueous solutions of methylcellulose at ultrasonic frequencies were investigated by a torsional method using quartz crystal resonators. The concentration dependences of G′ and G″ – ωη_s increased with increasing temperature at 13 kHz, but at higher frequencies G′ and G″ – ωη_s were simply proportional to the concentration irrespective of temperature. These results may be explained by the difference of corresponding viscoelastic mechanism at measuring frequencies. In order to examine the configuration of methylcellulose in water, which changes remarkably with temperature, the intrinsic values at various temperatures were experimentally obtained by extrapolation to zero concentration, and the frequency dependence of intrinsic dynamic viscosity was examined. The values of components of the complex intrinsic viscosity at various temperatures and their frequency dependences were quantitatively compared with those calculated from the Tschoegl theory. The values of hydrodynamic strength parameter in the Tschoegl theory for an aqueous solution of methylcellulose increased with increasing temperature, and an effect of the internal viscosity due to the aggregation of methylcellulose was observed at higher temperatures. However, on the whole, the viscoelastic behavior was relatively close to Rouse-like behavior.     

聚甲基丙烯酸甲酯-g-聚乙二醇单甲醚的合成及水溶液性质研究

采用主链接枝法合成了梳形表面活性剂聚甲基丙烯酸甲酯-g-聚乙二醇单甲醚(PMMA-g-MPEG).利用红外光谱(IR)、核磁共振氢谱(1HNMR)和凝胶渗透色谱(GPC)对其结构进行了表征.分别对PMMA-g-MPEG水溶液的浊点、表面活性及流变性质进行了研究.实验结果表明:其浊点大于90℃;25℃时,其临界胶束浓度为0.4 g/L,临界胶束浓度时的表面张力为48.7 mN/m;稀溶液近似为牛顿型流体,浓溶液具有强烈的剪切变稀的行为和黏弹性.     

Synthesis and rheological properties in aqueous solution of poly(acrylamide-co-sodium allylsulfonate)

The copolymerization of acrylamide (AM) with sodium allylsulfonate (SAS) was studied. The copolymerization rate equation was determined, R_p = K[KPS]^0.70[AM]^1.60[SAS]^?0.60. The copolymeric composition obtained by nitrogen and sulfur elemental analysis, and ¹H-NMR method. The reactivity ratios were calculated by the Kelen–Tudos method and the value of r₁(AM), r₂(SAS) was determined to be 2.45 and 0.060, respectively. The rheology of aqueous solution of synthetic poly(acrylamide-co-sodium allylsulfonate) was determined at different temperatures and flowing activation energy E_η were calculated.     

烷基二苄醚双季铵盐的合成及在水溶液中的聚集行为

以长碳链溴代烷、N,N-二甲基乙醇胺和对二溴苄为原料,合成了3种不同疏水链长的烷基二苄醚双季铵盐Gemini表面活性剂(10-B-10,12-B-12,14-B-14),采用FTIR、1HNMR和ESI-MS对其结构进行了表征。采用稳态荧光法测定了3种表面活性剂的临界胶束浓度(CMC)和胶束聚集数。结果表明,采用荧光法测定的CMC与表面张力法所得的值基本一致,随着疏水链长从10增加至14,CMC从3.24 mmol/L降至0.056 mmol/L。采用外推法得到3种表面活性剂的临界胶束聚集数(N m)分别为6.98(10-B-10),3.87(12-B-12)和1.62(14-B-14)。动态光散射结果表明,该类表面活性剂在CMC以上易生成囊泡,盐的加入会诱导囊泡转变成胶束。     

Surface properties and aggregation behaviors of amphiphilic highly-branched block polyethers in aqueous solution

A series of new highly-branched block polyethers, PA-PO-EO, were synthesized via anion ring-opening polymerization of propylene oxide (PO) and ethylene oxide (EO), using phenol-amine resin (PA) as the initiator. The molecular structures were confirmed by end group analysis, FT-IR and ¹H NMR. The surface properties and self-assembly behaviors in aqueous solution were investigated by surface tension, fluorescence spectroscopy, UV–vis spectra and TEM. The results indicated that the CMC of polyethers aqueous solution presented a wide range, and the scope of CMC corresponded to the content of EO. Moreover, the proportion of PA had a great effect on the properties of the whole polymer molecules, and the number of blocks was a critical factor to the process of self-assembly. A corresponding critical size of the spherical micelles formed by different samples was presented from TEM photographs. Accordingly, the possible self-assembly mechanisms were put forward to explain the formation of all kinds of aggregates. In a word, the PA and PPO blocks aggregated to form a relatively hydrophobic core, which was stabilized by a hydrophilic PEO corona.     

Viscosity properties of aqueous solution of poly(allylamine)-metal complexes

Poly(allylamine)-metal complexes with Co(II), Cu(II), and Ni(II) in conjunction with an ultrafiltration membrane were prepared. They were obtained varying the polymer/metal ion ratio and the pH (1, 3, 5, 7).     

两性离子型瓜尔胶的制备及稀溶液性质

以瓜尔胶(GG)为原料,2,3-环氧丙基二甲铵基乙酸盐(ECDH)为两性醚化剂,在碱催化剂作用下干法合成了新型两性离子型瓜尔胶(ZGG)。采用酸碱滴定法测定了ZGG的等电点,并借助乌氏黏度计研究了等电点范围内ZGG的稀溶液性质,考察了外加盐浓度和不同外加盐对ZGG的影响。结果发现,随着氯化钠溶液浓度的增大,其特性黏度增大,表现出明显的反聚电解质溶液行为,二价金属离子对ZGG的影响大于一价金属离子对其的影响,即CaCl2>MgCl2>NaCl。     

阴离子瓜尔胶的制备及其稀溶液性质

在碱催化剂作用下,用改性剂2-氨基乙磺酸钠-4,6-二氯-1,3,5-均三嗪与瓜尔胶反应制得新型阴离子瓜尔胶(AGG),采用IR对AGG进行了表征。借助乌氏黏度计研究了AGG的稀溶液性质,考察了温度和外加盐浓度对AGG的影响。结果发现,随着温度的升高,其特性粘度先增大后减小;而其特性粘度则随着NaCl溶液浓度的增加先减小后增大。