NaCl对疏水缔合聚合物溶液性质的影响研究

研究了NaCl对疏水缔合聚合物溶液性质的影响。结果表明,所合成的疏水缔合聚合物的特性粘数随NaCl浓度的增加而降低,其表观粘度则先降低后增加,继续增加NaCl浓度,溶液粘度降低,但仍保持很高的粘度。环境扫描电镜(ESEM)研究表明,疏水缔合聚合物在去离子水体系中会形成网状结构,而在NaCl浓度为5g·L-1的溶液中,ESEM照片显示疏水缔合聚合物的结构为致密的树枝状结构,且存在一临界缔合浓度。     

AMPS/DMAM/FA/AM共聚物的合成及溶液性能研究

本文采用氧化还原引发体系合成了AMPS（2-丙烯酰胺基-2-甲基丙烷磺酸钠）／DMAA（N,N-二甲基丙烯酰胺）／FA（富马酸）／AM（丙烯酰胺）共聚物,研究了共聚物的水溶液性能。结果表明,随聚合物浓度的增加,溶液表观粘度急剧增加;无机盐的加入使聚合物溶液的粘度下降,但很快稳定;随老化温度的提高,聚合物溶液的粘度有所增加;共聚物试样在盐水中表现出随剪切速率的增加,表观粘度增加。     

甲壳素溶液流变性能的初步研究

用热重分析仪和高级流变扩展系统分别研究了提纯工艺对甲壳素的影响和甲壳素／二氮乙酸溶液的流变特性。结果表明，提纯后的甲壳素为纯白色，且杂质含量减少。甲壳素／二氯乙酸溶液的表观粘度随剪切速率的增加而减小，结构粘度指数随浓度的增加而减小。剪切应力一剪切速率的曲线随着溶液浓度的增加而上移，浓度越大，其非牛顿指数n越小。该结构为确定合理的甲壳素纤维原丝生产工艺提供了科学依据。     

不同类型聚合物溶液对采油残余油的作用机理研究

通过实验测定了HPAM溶液和黄原胶溶液的流变性、在多孔介质中的流变性和残余阻力系数 ,计算了衰竭层效应 .用不同的浓度和注入速度进行了驱油实验 .提出聚合物分子缠结作用的增强不仅引起表观粘度增加或衰竭层厚度降低 ,而且使平行于油水界面的拉动残余油的力增加 ,从而使残余油饱和度降低 ,采收率提高 .随浓度增加 ,HPAM溶液的表观粘度和残余阻力系数增加 ,衰竭层厚度减小 ;黄原胶溶液的浓度高于缠结浓度时 ,衰竭层厚度和表观粘度变化不大 .注入速度增加时 ,两种聚合物溶液的衰竭层厚度均降低 ,HPAM溶液的残余阻力系数不变 ,粘弹性增加 ;而黄原胶溶液的残余阻力系数下降 .不同浓度和注入速度情况下两种聚合物溶液的驱油结果证实了文中提出的聚合物分子缠结作用和衰竭层效应对残余油的作用机理 .分子结构的不同是造成两种聚合物溶液在多孔介质中渗流规律和对残余油作用机理的差别的根本原因 .     

梳形支化聚苯乙烯的支化结构对其溶液形态和性质的影响

通过氮氧稳定自由基聚合和原子转移自由基聚合制备出不同支化结构的梳形支化聚苯乙烯.使用示差折光指数-多角激光光散射-毛细管黏度三检测联用凝胶渗透色谱对不同链结构梳形支化聚苯乙烯在四氢呋喃(THF)中的形态和性质进行了研究.结果表明,梳形支化PS在THF中的均方根回转半径(Rg)和特性黏数([η])均随支链长度和支链数目的增加而增大,但是在支链长度较长或者支链数目较大时,Rg和[η]随分子量增加而增大的趋势逐渐放缓,而且支链数目对梳形支化PS在溶液中的均方根回转半径和特性黏数的影响程度要大于支链长度.梳形支化聚苯乙烯在四氢呋喃中的MHS方程特性参数K、α随支链长度和支链数目的增加不断变化.     

羧甲基羟丙基瓜尔胶的流变特性

考查了羧甲基羟丙基瓜尔胶溶液的流变特性,发现其水溶液呈典型的假塑性,不同浓度下溶液表观粘度随剪切速率的变化可以用Ostwald-Dewaele方程描述;零切粘度与温度的关系符合Andrade方程;溶液的粘度在酸性条件下随溶液pH的减小迅速降低,在碱性条件下则变化不大;溶液对NaCl很敏感,表现出典型的聚电解质的特征。     

疏水基改性聚丙烯酰胺的合成及溶液性质

利用自由基胶束聚合法,由丙烯酰胺和甲基丙烯酸十八酯共聚合成了疏水缔合型水溶性聚合物.通过红外光谱表征了共聚物的结构,考察了共聚物浓度、盐浓度、剪切速率以及温度对共聚物溶液性能的影响.试验结果表明,聚合物质量分数大于临界缔合浓度(2%)时,溶液的粘度急剧增大;疏水缔合聚合物溶液的表观粘度随着溶液中NaCl质量分数的增加而增大.     

PS-b-PAA两亲性嵌段聚电解质在水溶液中的聚集行为及其流变特性

以两嵌段共聚物聚苯乙烯-b-聚丙烯酸(PS-b-PAA)为研究对象,采用动态光散射(DLS)及透射电镜(TEM)表征了胶束及聚集体的结构,采用应力控制型旋转流变仪AR-G2研究了体系的流变特性.着重考察了聚电解质浓度、pH值以及外加盐(KBr)浓度对其在水中聚集行为的影响及对体系流变特性的影响.发现随着外加盐和聚电解质浓度的增高,体系中的胶束发生聚集,形成更大的聚集体.而pH值对胶束的聚集形态无明显的影响.胶束乳液均呈现明显的剪切变稀特征.然而,随着聚电解质浓度增加,低剪切速率下体系的表观粘度增高;高剪切速率时体系粘度趋于同一值(0.01Pa·s).与纯胶束乳液相比,外加盐的存在导致体系粘度增加;当外加盐浓度增加至4.31g/L,在低剪切速率下,体系出现牛顿平台区.溶液pH值对体系粘度无显著影响.     

水溶性聚酯浓溶液的流变特性

研究了由对苯二甲酸二甲酯、间苯二甲酸、间苯二甲酸二甲酯 5 磺酸钠与乙二醇等共缩聚合成的PET型水溶性聚酯浓水溶液 (质量浓度 3 0 % )的流变特性 .研究表明 ,溶液的表观粘度随切变速率的变化规律呈现一定的切力增稠特征 ,流动指数范围为 1 0 4～ 1 2 0之间 ;其lgηa τ曲线呈线性 ,零切粘度值为 1 5 8～3 5 2cP ,随分子量、分子结构和温度而异 ,其中分子链中间苯二甲酸乙二醇酯 5 磺酸钠链节含量对溶液粘度影响较大 ;粘流活化能因分子结构和切变速率而变 ,其值范围为 1 2 0～ 2 3 9kJ/mol.     

氰乙基纤维素/二甲基甲酰胺液晶溶液的流变行为

本文通过测定不同浓度的溶液在不同温度和切变速率下的粘度,讨论了氰乙基纤维素/二甲基甲酰胺溶液的流变行为。溶液的流动曲线表明,该溶液是一种假塑性液体。在浓度较高时,存在屈服现象,屈服应力的大小与浓度和温度有关。溶液的浓度—粘度曲线表示出典型的液晶行为。粘度与浓度的关系和屈服应力与浓度的关系相似。溶液的临界浓度随温度的升高而增加。在单相区(各向同性相或液晶相),粘度随温度升高而降低,表观流动活化能大于零。但在两相区,粘度随温度的升高而增大,表观流动活化能小于零。该实验得到的临界浓度与通过光学的方法所得的临界浓度是一致的。     

Molecular Origin for the Thermal Stability of Rice Amylopectin 1

Abstract

The non-Newtonian behavior and dynamic viscoelasticity of Takanari and Reimei amylopectin solutions were measured with a rheogoniometer. The Takanari and Reimei amylopectin showed plastic behavior at a concentration above 2.0% at 25 °C. The viscosity of Takanari amylopectin decreased a little with increasing temperature at 2.0%. However, a little increase in the viscosity was observed with increasing temperature from 0 to 15 °C, then it stayed at a constant value with further increase in the temperature up to 80 °C at a concentration above 4.0%. An increase in the viscosity was also observed in Reimei amylopectin solution at various concentrations. The dynamic viscoelasticity of Takanari amylopectin increased with increasing concentration at low temperature (0 °C) and it stayed at a constant value with increasing temperature up to 80 °C. On the other hand, dynamic viscoelasticity for Reimei amylopectin showed a weak sigmoid curve. The tan δ of both amylopectins showed low values, 0.32-0.38, at low temperature range and kept constant with increasing temperature up to 80 °C. A little decrease of dynamic modulus of Takanari and Reimei amylopectin was observed upon addition of urea (4.0 M). The dynamic modulus of Takanari and Reimei amylopectin solution decreased rapidly when the temperature reached 45 and 60 °C, which was estimated to be a transition temperature, in 0.10 N NaOH solution. The molecular origin for the thermal stability of rice amylopectin (Takanari and Reimei) was essentially attributed to intramolecular associations in aqueous solution. Possible mode of intramolecular hydrogen bonding and van der Waals forces of attraction of amylopectin molecules are proposed.

     

丙烯酰胺型阴离子表面活性单体与丙烯酰胺共聚物水溶液的流变特性

以丙烯酰胺型阴离子表面活性单体2-丙烯酰胺基十四烷基磺酸钠(NaAMC14S)为共单体,与丙烯酰胺(AM)的水溶液均相共聚合,使NaAMC14S的浓度分别处于临界胶束浓度上下,分别制备了具有无规结构与微嵌段结构的两类共聚物;用红外光谱法对共聚物的结构进行了表征,使用乌氏粘度法测定了特性粘数,相对表示出了共聚物的分子量;采用荧光探针法与表观粘度法重点研究了两类共聚物的疏水缔合性与水溶液的流变特性.研究结果表明,具有微嵌段结构的共聚物具有很强的疏水缔合性,当其水溶液的浓度达0.2wt%后,表观粘度迅速提高;其水溶液的切力变稀行为具有明显的可逆性,表现出强的抗剪切性能.本研究中特别发现,具有微嵌段结构的共聚物其盐水溶液的表观粘度远高于纯水溶液的表观粘度,当共聚物浓度为0.3wt%、CaCl2浓度为2wt%时,溶液的表观粘度竟然提高了3个数量级,表现出独特的正性盐敏性(即遇盐变稠).     

Rheological Behavior of Aqueous Solutions of Cationic Guar in Presence of Oppositely Charged Surfactant

The cationic guar (CG) is synthesized and the rheological behavior of aqueous solutions of CG in the presence of sodium dodecyl sulfate (SDS) is studied in detail. The steady viscosity measurements show that the zero shear viscosity enhancement can be almost 3 orders of magnitude as the concentration of SDS increases from 0 to 0.043%. The gel-like formation is observed as the concentration of SDS is greater than 0.016%. The oscillatory rheological measurements of CG solutions in the presence of SDS show that the crossover modulus is almost independent of the concentration of SDS whereas the apparent relaxation time increases swiftly upon increasing the concentration of SDS. The experimental results indicate that the strength rather than the number of the cross-links is greatly affected bySDS molecules. The mechanism concerning the effect of SDS upon the rheology of CG solutions can be coined by the two-stage model. Before the formation of cross-links at the critical concentration, the electrostatic interaction between SDS and cationic site of CG chains plays a key role and the SDS molecules bind to CG chains through the electrostatic interaction. After the formation of cross-links at the concentration greater than the critical concentration, the cooperative hydrophobic interaction become dominant and SDS molecules bind to the cross-links through the hydrophobic interaction. The rheological behavior of aqueous solutions of CG in the presence of SDS is chiefly determined by the micelle-like cross-links between CG chains. In fact, the flow activation energy of CG solution, obtained from the temperature dependence of the apparent relaxation time, falls in the range of transferring a hydrophobic tail of SDS from the micelle to an aqueous environment.     

Apparent Molar Volume, Isentropic Compressibility, Refractive Index, and Viscosity of DL-Alanine in Aqueous NaCl Solutions

New experimental data at 25^°C for the density, velocity of sound, refractive index, and viscosity of aqueous solutions of DL-alanine and NaCl are reported. The apparent molar volume and isentropic compressibility of DL-alanine in aqueous electrolyte solutions have been calculated from the measured properties. The results show that DL-alanine exhibits a positive volume transfer to solutions of a higher NaCl concentration and a negative apparent isentropic compressibility for DL-alanine in the presence of NaCl. These effects indicate that the apparent volume of DL-alanine is larger in solutions with higher electrolyte concentration and the water molecules surrounding the DL-alanine molecules are less compressible than the water molecules in the bulk solution. The results also show an increase in the viscosity of the solution with an increase in both DL-alanine and NaCl concentrations. These effects are attributed to the two charged groups of DL-alanine and the interactions between the charged groups and the hydrocarbon backbone of DL-alanine with the ions. A model, consisting of a short-range interaction term represented by a virial expansion and a Debye-Hückel term that considers long-range interactions, has been developed to correlate the measured experimental data.     

Hydrophobically modified polyelectrolytes I. Dilute solution properties of fluorocarbon-containing poly (acrylic acid)

Dilute solution viscosity of fluorocarbon‐containing hydrophobically modified poly (acrylic add) was measured in aqueous solutions of various NaCl concentrations. The intrinsic viscosity ([η]) and Huggins coefficient (k_H) were evaluated using Huggins equations. It is found that, at low Nacl concentration, the modified polymers exhibit values of intrinsic viscosity ([η]) and Huggins coefficient (k_H) similar to those of unmodified polymers. For both of the modified and unmodified polymers, the intrinsic viscosity decreases with increase of NaCl concentration, while the Huggins coefficient increases upon addition of NaCl. But the variation of [η] and k_H is more significant for the modified polymers, which reflects the enhanced intra‐ and intermolecular hydrophobic association at higher Nacl concentration.     

Sulfation of polysaccharides with sodium pyrosulfate in dimethyl sulfoxide

Sulfo esters of cellulose, dextran, starch, and amylopectin with a degree of substitution equal to 0.1–1.1 were prepared in the system constituted by sodium pyrosulfate and dimethyl sulfoxide. The intrinsic viscosity of aqueous solutions of sulfo polysaccharides was determined, and their anticoagulant activity was evaluated.     

甲基丙烯酰氧基乙基三甲基氯化铵-丙烯酰胺-丙烯酸三元共聚物水溶液的盐效应研究

用恒定外加盐浓度稀释法,测定了甲基丙烯酰氧基乙三甲基氯化铵 丙烯酰胺 丙烯酸（ＤＭＣ ＡＭ ＡＡ） 三元共聚物（ＡＰＡＭ） 水溶液在分别添加不同种类外加盐时的特性粘数．实验结果表明,当外加盐浓度在一定范围内变化时,所有共聚物在ＮａＣｌ 溶液和ＮａＮＯ３ 溶液中均表现出典型的普通聚电解质粘性行为,而ＤＭＣ 和ＡＡ 近似等摩尔的共聚物在Ｎａ２ＳＯ４ 溶液中则呈现出典型的两性聚电解质粘性行为,各种外加盐对ＡＰＡＭ 溶液特性粘数影响的程度为：Ｎａ２ＳＯ４ ＞ ＣａＣｌ２ ,ＮａＮＯ３ ＞ ＮａＣｌ．     

十二烷基磺酸钠对丙烯酰胺－烯丙基磺酸钠共聚物溶液粘度的影响

丙烯酞胺-烯丙基磺酸钠共聚物(PASA)优良的絮凝性能已在前文^[1]中报道.本文主要考察阴离子表面活性剂R₁₂SO₃Na对其溶液粘度的影响,并与PAM做了对照.     

Effects of cationic head groups of ionic liquid on micellization in aqueous solution of PEO-PPO-PEO triblock copolymer

The interaction of ionic liquids (ILs) with non-ionic triblock copolymer, Pluronic® P123 in aqueous solutions has been investigated using DLS, surface tension, and viscosity measurements. The addition of ILs increased the Critical Micelle Concentration (CMC) of P123, which appears to be logistic. As the added IL enhances the solubility of PPO moiety (and PEO), which makes them to behave like a more hydrophilic block copolymer that would be micellized at high copolymer concentration. The DLS data is in good agreement to the results observed from surface tension measurements. Viscosity results show the propensity in micellar size reduction upon addition of ILs, and hence, intrinsic viscosity decreases as compared to pure P123 aqueous solution. The results are studied and discussed as a function of cationic head groups of N-octyl-pyridinium/imidazolium chloride based ILs.