脂肪醇聚氧乙烯醚硫酸钠黏弹性胶束及其流变与破胶性能

采用阴离子表面活性剂脂肪醇聚氧乙烯醚硫酸钠(AES)与NaCl制备黏弹性胶束。采用流变仪、黏度计和冷冻断裂蚀刻透射电子显微镜(FF-TEM),研究了在不同浓度条件下AES与NaCl溶液形成胶束体系的微观结构、流变性能、破胶机理以及重复利用性能。通过对溶液剪切黏度、剪切应力、动态模量、复合黏度等物理量的测量,结合体系宏观挑挂照片和微观FF-TEM分析,发现该体系在较宽的频率范围内呈现蠕虫状网状结构和优良的流变性能。NaCl对蠕虫状胶束的形成有很大影响,在一定的范围内随着NaCl浓度的增大,体系黏度显著增大;通过内相破胶剂实现了体系破胶可控性的目的,破胶后体系表现出分散均一的颗粒状,该体系具有重复利用的可行性。     

一种CO_2开关型粘弹性可逆流体的制备与性质

采用缩醛法对三乙烯四胺进行脒基化,获得一种二元脒基化合物,与十二烷基苯磺酸钠混合,制得粘弹性流体,考察了CO2、混合液配比、温度对流体粘弹性的影响。结果表明,在35℃下,当二元脒基化合物与十二烷基苯磺酸钠的摩尔比为1∶1.2时,溶液的粘弹性最佳,显示出蠕虫状胶束的特征,混合溶液的网络结构。     

Gemini表面活性剂黏弹性流体的流变性研究

C16-4-C16阳离子Gemini表面活性剂在NaCl和NaSal两种盐的作用下,可以形成蠕虫状胶束的黏弹性流体。采用流变仪研究了浓度、温度、剪切速率、剪切时间等因素对该流体黏度的影响,结果表明,2wt%的C16-4-C16流体在120℃下的零剪切黏度仍可达60mPa·s以上,而在80℃、170s~(-1)下剪切2 h黏度维持160mPa·s基本不变,说明该流体具有较强的耐温耐剪切性。触变实验的结果清楚地显示出该流体在不同的剪切作用下,蠕虫状胶束的形成与破坏是个可逆的过程。蠕虫状胶束间相互缠绕形成的网络结构,使流体具备了优异的黏弹性,高频有利于胶束储存能量,展现弹性形变;随着温度的升高,体系由弹性为主逐渐转变成了黏性较高的黏弹体,在60℃下黏性和弹性相当,展现了理想的Maxwell黏弹性流体的行为。     

一种CO_2开关型粘弹性可逆流体的制备与性质

采用缩醛法对三乙烯四胺进行脒基化,获得一种二元脒基化合物,与十二烷基苯磺酸钠混合,制得粘弹性流体,考察了CO2、混合液配比、温度对流体粘弹性的影响。结果表明,在35℃下,当二元脒基化合物与十二烷基苯磺酸钠的摩尔比为1∶1.2时,溶液的粘弹性最佳,显示出蠕虫状胶束的特征,混合溶液的网络结构。     

粘弹性表面活性剂流变性及研究

粘弹性表面活性剂的流变性包括其溶液流变性、低粘度特性、剪切稀释性在油田开发等许多方面有着极其重要的地位,粘弹性表面活性剂可作为理想的压裂液、酸化液、砾石填充及三次采油措施流体,有着极其出色的性能。详细介绍了粘弹性表面活性剂流变特性及研究现状;简要概述了粘弹性表面活性剂的研究方法极其在酸化、压裂等方面的应用,阐述了其典型优点及在现阶段油田应用中的不足。     

表面活性剂蠕虫状胶束缔合体系研究进展

介绍了表面活性剂蠕虫状胶束体系的研究进展情况,包括蠕虫状胶束的生长,稀溶液向亚浓溶液的过渡、粘弹体系的动态特性和非线性粘弹性以及剪切诱导粘弹性。     

压裂酸化用粘弹性表面活性剂溶液研究进展

粘弹性表面活性剂溶液的高表面活性及独特的流变特性可以作为理想的压裂、酸化、砾石充填等增产改造以及三次采油措施流体。详细介绍了粘弹性表面活性剂流体的组成、制备与表征方法,阐述了典型粘弹性表面活性剂流体流变特性研究现状;概述了粘弹性表面活性剂流体在压裂、酸化等增产措施中的应用进展,并指出了粘弹性表面活性剂流体矿场推广应用尚需解决的问题。     

NaSal/NaCl诱导阳离子蠕虫状胶束的形成及流变性研究

以阳离子三联表面活性剂双(2-羟基-二亚甲基醚)-α,ω,γ-三(十六烷基二甲基氯化铵)(TrimerC16)为主剂,水杨酸钠(Na Sal)为有机反离子,氯化钠(Na Cl)为无机反离子,制备了阳离子蠕虫状胶束体系。利用电导率-表观黏度法研究了TrimerC16的相行为,考察了不同有机反离子Na Sal、苯甲酸钠(Na BENZ)及甲酸钠(Na FM)对TrimerC16克拉夫特温度(Tk)的影响,通过动态流变手段研究了TrimerC16/Na Sal/Na Cl的流变行为,并采用表观黏度法考察了温度(T)及剪切时间(ts)对该体系表观黏度(ηa)的影响。结果表明:TrimerC16的临界囊泡浓度(CVC)为0.015 mmol?L?1,临界胶束浓度为0.042mmol?L?1;三种有机反离子对TrimerC16的Tk影响大小顺序为:Na SalNa BENZNa FM;剪切速率(r′)为100 s?1时,TrimerC16/Na Sal/Na Cl体系的黏度仍高达70 m Pa·s;T=100℃时,转速为50 r?min?1下,TrimerC16/Na Sal/Na Cl体系的ηa为61.8 m Pa?s,而同一测试条件下,相同摩尔浓度的单链表面活性剂胶束体系的ηa已接近水的黏度。TrimerC16/Na Sal/Na Cl蠕虫状胶束体系耐较高温、耐剪切且破胶彻底。     

一种胺基型阳离子表面活性剂的合成及其溶液性能

该文以2-氯乙胺盐酸盐和十八烷基叔胺为原料,合成了一种胺基型阳离子表面活性剂——N-十八烷基-N,N'-二甲基-乙基-1,2-胺。通过IR和1HNMR对其结构进行了确证;并得到优化的合成条件为:物料比nb/na为1.20,反应温度为70℃,反应时间为7 h,p H=7。采用电导法测定不同p H下该表面活性剂的临界胶束浓度(CMC),发现CMC随着p H的降低而减小。该表面活性剂在Na Sal溶液质量分数为1%时,能形成蠕虫状胶束。流变性能测试表明,体系具有蠕虫状胶束的剪切稀释性特征和凝胶特性,同时具有p H响应,能在酸性条件下增黏,是一种智能型蠕虫状胶束体系。     

水相和特殊介质中有序聚集体的结构、性质和应用(Ⅱ)——表面活性剂蠕虫状胶束

综述了近来关于表面活性剂蠕虫状胶束相态、平衡状态和动态的理论和实验结果以及应用冷冻蚀刻电镜照片直接观察到其结构。在一定条件下,表面活性剂在溶液中能可逆地缔合成为一种长的、有柔性的、甚至网状的蠕虫状胶束。它们具有类似柔软的高聚物溶液的线性黏弹性质,然而蠕虫状胶束经历裂解和再组合过程而表现复杂的流变性。最后介绍了蠕虫状胶束在油田、减阻剂和日用化工等方面的应用。     

表面活性剂聚集体的流变性质

以流变学基础知识为出发点，系统综述了胶束、微乳液，溶致液晶（层状、六角状、立方状），囊泡、虫状胶束等表面活性剂聚集体的流变性质及其剪切诱导结构转变现象的研究现状，总结了自流变性质的特点和理论模型，对具有黏弹性的表面活性剂活性剂聚集体进行了较为详细的论述，胶束稀溶液和微乳液多为牛顿流体；溶致液晶为非牛顿流体，有应力服价值和较高的黏弹性，囊泡的弹性性质比较突出，；虫状胶束体系具有非线性黏弹性，易形成网络结构；层状液晶、囊泡和虫状胶束等结构在剪切作用下能发生变化。这些结论对指导表面活性剂的研究和应用有重要意义。     

Rheology on novel viscoelastic trimeric octadecyl zwitterionic surfactant micelle solutions

In this work, a novel trimeric octadecyl zwitterionic surfactant (TOCC) was successfully synthesized. TOCC was compounded with sodium salicylate (NaSal) for an optimized formulation to form viscoelastic micelles. The effects of NaSal concentration, pH, and temperature on the rheological properties of TOCC and TOCC/NaSal micelle solutions were investigated. The flow curves for both TOCC and TOCC/NaSal micelle solutions can be fitted with the Carreau–Yasuda model. Zero shear viscosity of TOCC/NaSal micelle solution increased and then decreased with increasing NaSal concentration, and the same trend was observed for viscoelasticity. Some micelle solutions exhibited significant thixotropy with stress overshoot. The optimal composition of the TOCC/NaSal micelle solution obtained was 5.0/0.5 wt%. Frequency sweep in the form of Cole–Cole plots indicated that the viscoelastic modulus of the TOCC/NaSal micelle solution fitted the Maxwell model at low and medium frequencies. With increasing pH, 5.0 wt% TOCC micelle solution had the maximum zero shear viscosity at pH = 6.9. The steady-state viscosities of different concentrations of TOCC micelle solutions reached their maximum at neutral conditions (pH = 6.5 ~ 7.0). Viscoelastic modulus of 5.0 wt% TOCC and TOCC/NaSal (5.0/0.5 wt%) micelle solutions decreased with increasing temperature, and thermal thixotropy was observed in both micelle solutions. The novel TOCC and TOCC/NaSal micelle solutions enrich the variety of trimeric surfactants and viscoelastic micelle solutions. This study provides a rheological reference for the applications of viscoelastic trimeric surfactants in smart materials and oil fields.     

蠕虫状胶束的黏弹性及其应用

文章主要叙述了在流变性上具有其特有性质的一种非常重要的表面活性剂聚合结构,即黏弹性蠕虫状胶束的重要应用。其内容包括了由阴离子,两性离子和高分子表面活性剂形成的相应体系。应用范围更是涉及了油田化学品,药物减水剂和个人护理品及家居用品的增浓等。     

Rheological properties of ethylcellulose latex

Because of their large specific surface area, aqueous‐based pseudolatex systems of ethylcellulose can absorb large amounts of drugs. In addition, the stability of polymeric particles in biological fluids delays the release of the drug as in controlled drug delivery systems. The aim of the present study was to characterize the rheological properties of latex particles as a measure of their colloidal stability. Here, we report the effect of three variables: pH, electrolyte concentration, and temperature. The rheograms clearly show that the polymer suspensions displayed Bingham plastic behavior. Internal structuring of the latex was greatest at acid and natural pH values, particularly at the highest ionic strength. In acid solutions, only temperature appeared to play a fundamental role; both the shear stress corresponding to the onset of nonlinear viscoelasticity and the elastic modulus at all frequencies were higher at 37°C than those at room temperature. This is assumed to be a consequence of deformation of the polymer particles upon heating. The effect of ionic strength was noticeable only at the natural pH (pH ? 6.5). At high concentrations of sodium chloride, the particles aggregated because of the decrease in double layer repulsion, and as a result, the latex became structured and its elastic modulus subsequently increased. Interestingly, when the temperature was increased further, this structure presumably broke, down, at least partially, and the storage modulus was reduced. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 847–851, 2006     

Rheological behavior of alginate solutions for biomanufacturing

The rheological behavior of alginate solutions were investigated for the optimal design of a biomanufacturing system to produce alginate structures for tissue engineering. Its rheological properties were determined by a rheometer through rotational and oscillatory tests. Experimental results were used to model the alginate solutions characteristics. The findings suggest that alginate solutions undergo shear‐thinning effects with increasing shear rates. It is also possible to observe that its loss modulus is higher than the storage modulus ones being both modulus dependent upon the frequency, which is a typical characteristic of dilute solutions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Rheological characterization of mechanical properties of chemically crosslinked microspheres

This work presents a rheological method to characterize degradation of microspheres made of chemically crosslinked hydrogels. Conditions to measure rheological properties of microspheres, remaining as individual microspheres during measurement, were established. Relevant and reproducible measurements could be obtained with a rheometer equipped with a parallel plate geometry in which a homogenous and continuous monolayer of microspheres was inserted in a gap between the plates. The storage modulus of microspheres was determined under an imposed strain of 0.04% with an oscillatory measurement mode at various frequencies. The microspheres showed almost purely elastic behavior while their storage modulus was affected by the degree of crosslinking. In the second part of the work, the rheological method was applied to investigate the degradation of microspheres made of a hydrolyzable crosslinked hydrogel. The method was found suitable by measuring the storage modulus over time. A good correlation was identified between acidification of the incubation medium because of the release of degradation products and the decrease of the storage modulus of the microspheres indicating a reduction in the crosslinking of the hydrogel resulting from the degradation process. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Cross-linkers control the viscoelastic properties of soybean oil-based biomaterials

Because of environmental concerns, biodegradable materials have been of increasing research interest over the last several years. Previously, we reported on a biobased material developed from epoxidized soybean oil (ESO) that displayed viscoelastic behavior similar to synthetic rubbers or plastics. In this work, the viscoelastic properties of several biomaterials made from ESO cross-linked by different amounts of two different cross-linking agents were investigated. The composites exhibited different glass transition temperatures and viscoelastic behaviors depending on the type and amount of cross-linker used. Higher glass transition temperatures and stronger viscoelastic properties of the materials were found with a greater amount of cross-linker. Comparing agent triethylene glycol diamine (TGD) with agent triethylenetriamine (TETA), we found that the material cross-linked by TETA had a higher glass transition temperature and stronger viscoelastic solid properties than the material cross-linked by the agent TGD.     

Thermal and viscoelastic properties of some commercial starch products

Three commercial starch products for polyolefins, marketed under the Mater‐Bi, Cornplast, and Bioefect trademarks, were subjected to an accelerated soil burial test. Their thermal and viscoelastic behaviors were studied by differential scanning calorimetry (DSC) and dynamic mechanical spectroscopy. Degradation in soil leads to more significant changes both in the DSC thermogram and the mechanical relaxation spectrum of Mater‐Bi. The relaxation spectra of Cornplast and Bioefect, two products containing polyethylene, basically coincide with that of pure low density polyethylene. The α‐relaxation zone of these starch products is the most affected by the degradation process. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1242–1251, 2003     

Nonlinear viscoelastic properties of molten thermoplastic vulcanisates: An insight on their morphology

A series of thermoplastic vulcanisates (TPVs) in the molten state were submitted to large amplitude oscillating strain tests at different frequencies, to investigate their nonlinear viscoelastic properties. A purposely modified torsional harmonic tester with a closed cavity was used to run such experiments, whose results were treated with a Fourier transform (FT) algorithm to extract main torque and strain components, and harmonics if any. Quarter cycle integrations of (averaged) torque signal were also performed, to supplement FT analysis, namely to distinguish extrinsic and intrinsic nonlinear viscoelasticity. The nonlinear viscoelastic character of TPVs was found substantially differing from the one of a molten polypropylene (PP) used for comparison. Within the strain window investigated, no linear behavior is observed with TPVs, in contrast with the pure PP. However, extrapolated “linear” complex modulus G*₀ tends to decrease with increasing hardness of TPVs, but subtle differences between the various grades are clearly detected, when using simple models to fit experimental data. While the (room temperature) hardness is somewhat related with the viscoelastic behavior in the molten state, the strain sensitivity of TPVs appears essentially affected by the extractible content (mainly oil). TPVs nonlinear viscoelastic character appears to depend on the strain amplitude: mainly intrinsic, i.e., due to their morphology, at low strain, and essentially extrinsic, i.e., due to the large strain amplitude, at high strain, and in this respect, qualitatively similar to pure PP. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4193–4205, 2006