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。     

一种部分水解聚丙烯酰胺的合成及性能评价

分别选用丙烯酰胺、丙烯酸、DMMAC作为主链单体、亲水单体及疏水单体,合成了一种三元共聚高相对分子质量部分水解聚丙烯酰胺,其具有较大的分子量,较好的化学稳定性和热稳定性。同时,该聚合物产品的固含量较高,可达51.35%。此聚合物溶液在0.0008416 g/mL的浓度下就具有较高的黏度,高达1.4614,是一种不错的增稠剂。本次研究所合成的聚合物材料的粘均分子量约为166万,分子量较大,具有优良的溶胀特性,在聚合物驱中应用前景广阔。     

基于离子液体的聚丙烯腈/纤维素溶液的动态流变性能研究

采用旋转流变仪分别对以离子液体1-烯丙基-3-甲基咪唑氯盐[AMIM]Cl,1-丁基-3-甲基咪唑氯盐[BMIM]Cl,1-乙基-3-甲基咪唑醋酸盐[EMIM]Ac为溶剂的聚丙烯腈/纤维素共混溶液(分别标记为溶液A,B,E)的动态流变性能进行了研究,讨论了溶液的储能模量(G′)、损耗因子(tanδ)及角频率(ω)之间的关系。结果表明:A、B溶液lgG′-lgω曲线分别在70,90℃开始呈现"第二平台",且随温度升高,平台宽度变大;A,B溶液时温叠加主曲线分别在70,100℃下的低频区域发生偏离,表明时温等效原理在低频下对于G′失效,E溶液不符合时温等效原理;A,B溶液tanδ随ω增大而降低,E溶液则升高;A,B溶液lgG′～lgG″曲线分别在80,110℃时发生偏离,在测试温度范围内对温度具有依赖性,E溶液lgG′-lgG″呈非线性关系;A,B溶液的Cole-Cole曲线出现拖尾现象。     

二醋酸纤维素/离子液体溶液流变性能的研究

以离子液体1-丁基-3-甲基咪唑四氟硼酸盐([Bmim]BF4)为溶剂,制备了不同质量分数的二醋酸纤维素(CDA)/[Bmim]BF4溶液,采用旋转流变仪研究了溶液的稳态和动态流变行为,讨论了剪切速率、温度和CDA含量等因素对CDA/[Bmim]BF4溶液黏度的影响,并考察了Cox-Merz法则对CDA//[Bmim]BF4溶液体系的适用性。结果表明:CDA/[Bmim]BF4溶液为假塑性流体,表观黏度和零切黏度均随着质量分数的增加和温度的降低而增大;溶液的黏流活化能随着溶液质量分数增加增大;溶液不符合Cox-Merz法则;随着CDA/[Bmim]BF4溶液浓度增加,溶液中CDA大分子相互作用加剧,高浓度的CDA/[Bmim]BF4溶液需要更长的松弛时间。     

离子液体在聚硫密封胶中的应用

为研究ILs(离子液体)不同于传统助剂的特殊功能,在聚硫密封胶中加入了不同种类的ILs,随后对密封胶的硫化特性、力学性能、耐热性及耐油性等进行了考察。研究结果表明:不同种类的ILs在硫化过程中的促进(或延缓)作用并不相同;在力学性能方面,ILs与普通增塑剂的作用相似,加入后会使密封胶的强度降低、韧性提升;与传统增塑剂相比,ILs明显增强了密封胶的耐热性和耐油性,并且ILs具有特殊的触变作用,可有效改善密封胶的施工性能。     

液体聚硫橡胶的性能与应用

介绍了液体聚硫主链含硫原子和饱和的分子结构,具有耐油、耐老化等性能,能用喷涂、浇注等加工方法施工,广泛用作各工业部门的胶粘剂、密封剂、涂层材料等。     

改性聚硫密封胶的制备及性能研究

为提高聚硫密封胶与金属的粘接性能,以EP(环氧树脂)和PF(酚醛树脂)作为聚硫密封胶的复合增黏树脂,并着重探讨了增黏树脂配比对聚硫密封胶制备工艺、力学性能及粘接性能等影响。研究结果表明:当m(EP)∶m(PF)=10∶10时,聚硫密封胶的综合性能相对较佳,此时其拉伸强度、断裂伸长率和180°剥离强度分别为2.26 MPa、338%和1.95 kN/m。     

金属阳离子对部分水解聚丙烯酰胺溶液黏度影响的研究进展

综述了金属阳离子对部分水解聚丙烯酰胺溶液（HPAM）黏度影响的研究现状,解释了不同价态金属阳离子对HPAM的降黏作用机理,介绍了采油污水处理中金属离子的脱除技术。对目前金属离子与HPAM作用研究中存在的问题以及未来的发展方向进行了总结。     

聚硫密封剂耐喷气燃料老化性能研究

聚硫橡胶是一种中温材料,其耐温等级(最高使用温度仅为120℃)已无法满足某些领域的使用要求。为此,以聚硫密封剂经3号喷气燃料150℃/24 h处理后的力学性能作为衡量指标,采用单因素试验法分别考察了不同类型的防老剂、硫化剂、填料和促进剂等对聚硫密封剂耐老化性能的影响。结果表明:在其他条件保持不变的前提下,当硫化剂为活性二氧化锰、补强填料为炭黑和防老剂为4020时,聚硫密封剂的耐老化性能相对最好;促进剂的类型对聚硫密封剂的耐老化性能基本无影响。     

水解方法对疏水改性聚丙烯酰胺的性能影响

采用水溶液自由基胶束共聚法,通过氧化还原体系引发丙烯酰胺与自制功能单体聚合,以均聚后水解与均聚共水解方法分别制得疏水改性聚丙烯酰胺(HMPAM)。通过探针芘的荧光光谱、扫描电镜和表观粘度测定等手段,表征了HMPAM溶液中疏水缔合作用及分子聚集形态,研究了不同水解方法导致的浓度、温度、矿化度对HM-PAM溶液流变性能的影响。结果表明,均聚后水解产物分子量(1 000多万)大于均聚共水解产物的分子量,并且其在盐水溶液中存在明显的临界缔合浓度。但是均聚共水解产物产物在高温、高矿化度及97 d的老化实验条件下,其粘度保留率高于均聚后水解产物。     

Characterization and solution properties of a partially hydrolyzed graft copolymer of polyacrylamide and dextran

Graft copolymers of dextran (Dx) and polyacrylamide (PAM) were synthesized through the grafting of PAM chains onto a Dx backbone with a ceric‐ion‐induced solution polymerization technique. By the variation of the amount of the initiator (ceric ammonium nitrate), four different grades of graft copolymers were synthesized. The partial alkaline hydrolysis of Dx‐g‐PAM was carried out in an alkaline medium. Three grades of partially hydrolyzed products were synthesized through the variation of the amount of alkali. These hydrolyzed graft copolymers were characterized with elemental analysis, infrared spectroscopy, neutralization equivalent measurements, a rheological technique, scanning electron microscopy, thermal analysis, viscometry, and X‐ray diffraction. The flocculation efficiency and viscosifying characteristics of the graft copolymers were enhanced upon their alkaline hydrolysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008.     

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     

Characterization of the conformational changes of partially hydrolyzed polyacrylamide chains in solution using stress recovery experiment

In this study, a simple empirical decay function model is fitted to the experimental data to characterize the conformational changes of partially hydrolyzed polyacrylamide (HPAM) in semidilute solutions, using the stress recovery experiment after cessation of a steady shear flow processing. With the increase of HPAM concentration and NaCl concentration, the parameter κ decreases, and this is in excellent agreement with the conformational changes of HPAM molecule chains. Experimental results show that the parameter κ can provide some information on the changes of the polymer chain conformation. the polymer chain conformation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2709–2713, 2006     

Hydrolysis and thermal stability of partially hydrolyzed polyacrylamide in high-salinity environments

Partially hydrolyzed polyacrylamide (HPAM) is the water-soluble polymer most often used in flooding applications in the petroleum industry. However, in aqueous solutions at high temperatures, HPAM undergoes hydrolysis of the lateral amide groups, and the presence of salts in the solution can lead to precipitation of this polymer. Therefore, a method was developed to monitor the thermal stability of HPAM solutions in different saline environments and varying temperatures. The proposed test method involved measurements of intrinsic viscosity as a function of time and determination of the degree of hydrolysis of the HPAM by elemental analysis. The results obtained indicated that the presence of divalent cations (Ca⁺² and Mg⁺²) negatively influenced the intrinsic viscosity of the solutions and in some systems led to precocious precipitation of the polymer in environments with higher concentrations of these cations. The hydrolysis reaction of the amide groups to the acrylate groups of the HPAM chain was significantly affected by rising temperature: at 50 °C, hydrolysis occurred, but not as significantly as at 70, 85, 90, and 95 °C. Hydrolysis up to 84% was observed for solutions processed at 90 °C. The results also indicated limits of hardness for the brine at some temperatures: 1353 ppm for 95 °C and 2867 ppm for 70 °C. For brine containing 13,610 ppm or more of divalent cations, hydrolysis and precipitation of the polymer were not observed at 50 °C. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47793.     

次氯酸钠氧化法测定聚丙烯酰胺浓度的研究

阐述了次氯酸钠氧化法（浊度法）测定部分水解聚丙烯酰胺浓度的反应机理，研究了聚丙烯酰胺的相对分子质量、次氯酸钠溶液浓度、反应时间对吸光度值的影响，针对大庆油田杏二中三元复合驱采出水中含有碱和表面活性剂、pH值高、黏度大、富集硫化物和亚硫酸根等特点，提出采用过硫酸铵一浊度法检测三元复合驱采出水中聚丙烯酰胺浓度。     

Studies on determination of molecular weight for ultrahigh molecular weight partially hydrolyzed polyacrylamide

The molecular weight characterization of partially hydrolyzed polyacrylamide (HPAM) for enhanced oil recovery use is rather difficult because of its ultrahigh molecular weight copolymer and polyelectrolyte behaviors in solution. In this work the effects of aqueous NaCl solution concentration and degree of hydrolysis of polymer on molecular dimension were studied. A simple and precise method for determining molecular weight of HPAM is presented. The molecular weight of HPAM with any degree of hydrolysis can be calculated from the [η]−M_w equation of unhydrolyzed PAM in an H₂O system by measuring , of HPAM obtained in aqueous NaCl solutions by extrapolating salt concentration to infinity. Because the values of of HPAM of different degrees of hydrolysis are all equal to the corresponding [η] value of the unhydrolyzed PAM of the same degree of polymerization, the molecular weight of HPAM of any degree of hydrolysis can thus be calculated from the [η] − M_w equation for PAM homopolymer. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of partially hydrolyzed polyacrylamide nanocomposite weak gels with high molecular weights

High‐molecular‐weight partially hydrolyzed polyacrylamide nanocomposite (HPAMNC) weak gels were synthesized and evaluated for their flooding behaviors in oil‐recovery applications. The structure, morphology, and properties of the obtained HPAMNC samples and their weak gels were characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). XRD patterns clearly proved the exfoliation of the montmorillonite (MMT) layers in the polymer matrix; this was consistent with TEM analysis. The morphology of the HPAMNC was proven to be in a cross‐wire aggregated form by SEM analysis. The viscosity‐average molecular mass of the obtained HPAMNC was approximately 8.51 × 10⁶ under the optimized MMT load at 1.0 wt %. The flooding experiments showed that the oil‐recovery rates in sand pack tubes with low and high permeability were enhanced by approximately 35.1 and 46.2%, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42626.     

Dependence of intrinsic viscosity and molecular size on molecular weight of partially hydrolyzed polyacrylamide

As a typical water-soluble polymer, ultra-high molecular weight (UHMW) partially hydrolyzed polyacrylamide (HPAM) has been widely used in various industries as thickeners or rheology modifiers. However, precise determination of its critical physical parameters such as molecular weight, radius of gyration (R_g) and hydrodynamic radius (R_h) were less documented due to their high viscosity in aqueous solution. In this work, the molecular structure of five UHMW-HPAM samples with different MW was elucidated by ¹H and ¹³C NMR spectroscopy, and their solution properties were characterized by both static and dynamic light scattering. It is found that all the second virial coefficient (A₂) values are positive and approaching zero, indicating of a good solvent of 0.5 M NaCl for UHMW-HPAM. The weight-average molecular weight (M_w) dependence of molecular size and intrinsic viscosity [η] for these series of HPAM polymers with MW ranging from 4.81 to 15.4 × 10⁶ g·mol⁻¹ can be correlated as R_g = 3.52 × 10⁻²M_w^0.51, R_h = 1.97 × 10⁻²M_w^0.51, and [η] = 6.98 × 10⁻⁴ M_w^0.91, respectively. These results are helpful in understanding the relationship between molecular weight and coil size of HPAM polymers in solution, and offer references for quick estimation of molecular weight and screening of commercial UHMW-HPAM polymers for specific end-users.     

Synthesized graphene oxide and fumed aerosil 380 dispersion stability and characterization with partially hydrolyzed polyacrylamide

Hydrolyzed polyacrylamide(HPAM)is a commonly used polymer for the chemicals,mining and refining processes of hydrocarbon but suffers from a persistent high-temperature instability problem.In contrast,the nanoparticle suspension remains a technical challenge because of the strong interactions of van der Waal forces within nanoparticles,which always encourage aggregation.This research sought to improve nanoparticles(NP)stability and polymer(HPAM)rheological properties to improved hydrocarbon recov-ery by utilizing synthesized graphene oxide(GO)nanosheets and fumed Aerosil 380 Silica oxide(SiO2).The aqueous nanocomposites based on HPAM-GO and HPAM-SiO2 in aqueous polymeric solutions have been developed,and its viscoelastic and static behaviour is studied.The results imply that by adding fumed silica NP,the viscoelastic behaviour of HPAM is marginally improved,particularly in high temper-atures and salinity,however,the inclusion of GO's significantly improves the viscosity and stability of the base polymer fluid at high temperatures.The Fourier data for the transformation of the infrared spectrum confirmed that the hydrogen bonding formed between HPAM carbonyl groups and silica NP surface sila-nol functionality and covalent interlinking of electrostatic h-bonding between HPAM and functional GO contributed to the improved stabilization and improved rheological performance that helps to recover high salinity and temperature hydrocarbons.     

On the correlation between the viscosity of partially hydrolyzed polyacrylamide solution and the diffusion coefficient in the semidilute concentration regime

The solution viscosity of neutral polyacrylamide (PAM), the partially hydrolyzed polyacrylamide (70% HPAM), and polyacrylic acid (PAA) were measured concurrently with the apparent diffusion coefficient in the dilute and semidilute concentration regimes. We identified the scaling relation η − η_s = A/D in the semidilute regime, where η is the solution viscosity, η_s is the solvent viscosity, D is the coefficient of the slow diffusion mode obtained from dynamic light scattering, and A is a prefactor found to have a unique value of ∼1.0 × 10⁻⁸ cP cm²/s. The scaling relation as well as the prefactor are independent of the the ionic strength, the solvent quality, the molecular weight, the charge density, the polyelectrolyte, and salt concentrations. For the neutral PAM, the product [η – η_s]D is proportional to the polyelectrolyte concentration C_p, consistent with Rouse theory and previous experimental findings.