聚丙烯酰胺水溶液的流变性质

粘性指进现象;聚丙烯酰胺水溶液的流变性质     

过硫酸钾-脲氧化还原引发下的丙烯酰胺水溶液聚合

为制备高分子量聚丙烯酰胺(PAM),对其引发体系,尤其是对氧化还原引发做了许多探索^[1]。     

极低剪切速率下聚丙烯酰胺溶液在毛细管中的流变特性 Ⅰ.温度和聚丙烯酰胺浓度对流变性能的影响

流变行为;光学;流变仪;极低剪切速率下聚丙烯酰胺溶液在毛细管中的流变特性 Ⅰ.温度和聚丙烯酰胺浓度对流变性能的影响;屈服应力;流变性能     

聚丙烯酸/聚丙烯酰胺水溶液复合特性的研究

通过酸度、电导率、粘度、接触角的测定,研究了聚丙烯酸 (PAA) /聚丙烯酰胺 (PAM) 水溶液复合物及复合物膜的结构和性能。结果表明,酸度、温度、浓度和复合比影响PAA/PAM的复合水溶液中大分子链的构象和流体力学体积,适度的氢键作用可以形成均相的复合溶液。经过热处理和未经热处理的聚合物膜表现出了不同的亲水性能。     

疏水缔合效应对聚丙烯酰胺类水溶液结构和流变性质的影响

以聚合物驱油为背景,研究了部分水解聚丙烯酰胺(HPAM)和缔合型部分水解聚丙烯酰胺(AHPAM)水溶液的结构与流变性质的差别.通过粘度法和静态激光光散射法得到了所分析的聚丙烯酰胺的分子量,用动态激光光散射法和粘度法分析了特定AHPAM分子缔合形态,并用流变学法测定了AHPAM在地层温度与矿化度条件下的线性粘弹性与非线性流变特性.着重讨论了临界缔合浓度的概念,研究了结构和流变性质的关系,以及分析了缔合对聚合物驱油的可能影响.实验结果表明,AHPAM水溶液在宽浓度范围存在分子缔合;一般临界缔合浓度的概念实际反映在进入亚浓溶液范围分子间缔合的效应,剪切速率约为10 s-1时,剪切粘度突降数倍,反映缔合结构在剪切场中的变化,该现象在高缠结浓度下较不明显;拉伸粘度随拉伸速率变化与HPAM定性不同,该拉伸特性反映了疏水缔合近程作用的本质.     

改性聚丙烯酰胺水溶液的疏水缔合性质

合成了一种疏水缔合水溶性聚丙烯酰胺共聚物,使用荧光光谱法并结合紫外及流变性实验,对制备的疏水缔合水溶性聚丙烯酰胺共聚物在水溶液中形成疏水微区、超分子聚集体及空间网络结构进行了研究,并用扫描电子显微镜证实了溶液中网络结构的存在.     

丙烯酰胺水溶液聚合──添加Na_2CO_3制取高分子量阴离子型速溶聚丙烯酰胺的研究

本文建立了丙烯酰胺水溶液聚合的潜在型引发体系；研究了在碳酸盐法聚合体系中，添加不同量氨、尿素、ＥＤＴＡ—２Ｎａ，以及聚合体系ｐＨ、单体浓度、聚合水浴温度对聚合产物分子量及其溶解性能的影响规律和原因；解决了产物高分子量与产生不溶聚合物之间的矛盾；指出了获得高分子量阴离子型速溶粉末产品的关键．从而，用碳酸盐法得到了溶解性能优异的［η］高达２８ｄｌ／ｇ的胶体产品和［η］高达２２ｄｌ／ｇ的速溶粉末产品．     

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).     

新型阳离子聚丙烯酰胺离解行为的研究

前文曾报导,以聚丙烯酰胺为母体,通过甲醛为桥梁引入二氰二胺可合成一种新型阳离子聚电解质,简称PAm·MG,它是一种弱聚碱的盐酸盐,结构式如下(S 为取代度):PAm·MG 对含活性艳红染料的废水有明显的絮凝脱色作用,其絮凝效果受聚合物的取代度、介质的pH 以及外加盐浓度的影响,而这些影响因素又直接与聚碱的离解行为或胺基离子化度(指已离子化的胺基占全部胺基的分数)密切相关.为此,本文对影响PAm·MG 离解行为和离子化度的一些因素作进一步探讨,并通过粘度测定考察离解行为对聚合物在水中形态的影响,为PAm·MG 的实际应用提供理论根据.     

疏水缔合聚丙烯酰胺的合成及溶液性能研究

水溶性疏水缔合聚合物是在聚合物亲水主链上引入极少量疏水基团(一般小于2ｍｏｌ%)而形成的一种新型水溶性聚合物[1]。由于这类聚合物具有独特的流变性能,因而备受学术界和工业界关注。目前已作为涂料增稠剂[2]和流变改性剂[3]得到了应用,而通过在部分水解聚丙烯酰胺(ＨＰＡＭ)的亲水主链上引入少量疏水单体而形成的疏水缔合聚丙烯酰胺(ＨＡＰＡＭ)则可望克服ＨＰＡＭ耐温、耐盐性差的缺陷[4]而作为新一代水溶性聚合物材料用于油气开采作业[5,6]。由于亲水单体和疏水单体的不相容性,通常通过在反应溶液中加入表面活性剂使亲水单体和疏水单体…     

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.     

一维粒子对聚乙烯醇水溶液流变行为的调控

将一维粒子(碳纳米管, CNTs; 碳纳米纤维, CF)加入聚乙烯醇(PVA)水溶液中, 考察碳粒子表面含氧官能团含量(羟值)、 长径比、 温度及PVA本体溶液浓度等对复合体系流变行为的影响. 结果显示, 复合溶液的黏度(η)随CNTs用量({\phi }_{\mathrm{C}\mathrm{N}\mathrm{T}\mathrm{s}})先增大后降低, 然后继续增大, 呈“N”形变化趋势, 出现两个拐点({\phi }_{\mathrm{1}}和{\phi }_{\mathrm{2}}). 在{\phi }_{\mathrm{1}}附近, CNTs主要起物理交联点作用, 体系η增加; 在{\phi }_{\mathrm{2}}附近, CNTs对PVA分子间氢键作用破坏最为严重, 体系η低于纯PVA溶液, 表明不同羟值CNTs仅改变其用量即可使PVA水溶液增黏或降黏. 随着羟值增大, CNTs与PVA大分子间相互作用加强, {\phi }_{\mathrm{1}}和{\phi }_{\mathrm{2}}减小, {\phi }_{\mathrm{2}}对应的η下降, 降黏效果显著. CNTs的加入使PVA水合数下降, 羟值大的CNTs可与PVA上更多的羟基形成氢键作用, 水合数更低. 随着{\phi }_{\mathrm{C}\mathrm{N}\mathrm{T}\mathrm{s}}增大, 复合体系黏流活化能增大. CNTs对不同质量分数PVA水溶液的η具有类似的调控作用, 但调控幅度有差异. 相同羟值、 不同长径比的CNTs对PVA水溶液的黏度调控均呈“N”形变化, 长径比小的CNTs复合体系, {\phi }_{\mathrm{1}}和{\phi }_{\mathrm{2}}较大. 长径比相近但直径较大的CF复合体系表现出更低的{\phi }_{\mathrm{1}}和{\phi }_{\mathrm{2}}.     

季铵盐Gemini表面活性剂胶团水溶液的流变性质

用毛细管振荡剪切流动法研究联接基团为聚亚甲基链的季铵盐型Gemini表面活性剂C_12-s-C₁₂·2Br(s=2,4,8)的流变性质,并用动态光散射技术测定胶团生长过程中的胶团形状和大小的变化规律,探索联接基团长度对胶团形状、大小以及溶液流变性质的影响.实验结果表明,胶团形状和大小与联接基团长度有关,而溶液的流变性质主要由胶团的大小和形状所决定,球形和棒状(长椭球体)胶团溶液的流变性质以纯粘度为主,而线性胶团溶液则显示粘弹性质.此外,增加电解质浓度和降低温度均使溶液的粘度增大.     

两性瓜尔胶衍生物溶液的流变特征

借助旋转粘度计研究了一种两性瓜尔胶衍生物(E-AMPHO-S)溶液的流变特征，考察了衍生物浓度、外加盐和温度对E-AMPHO-S溶液流变性能的影响.发现在实验条件下， E-AMPHO-S溶液呈非牛顿流体特征，具有剪切变稀特性；随改性瓜尔胶浓度增大， E-AMPHO-S溶液具有增强的触变性质；在一定浓度盐溶液中， E-AMPHO-S可表现出明显的反聚电解质溶液粘性行为；E-AMPHO-S溶液的零切粘度可由Spencer-Dillon方程外推得出，其与温度的依赖关系服从Arrhenius公式.     

Phase Behavior and Rheological Properties of Concentrated Lecithin Aqueous Solutions with Additives

The phase behavior and rheological properties of the concentrated lecithin aqueous solutions were investigated at 37°C. When adding Isopropyl myristate (IPM) to lecithin solutions, besides an anisotropic liquid crystal (LC) phase, an isotropic liquid (L₂) region and an isotropic viscous (I) phase are found. By continuously adding Brij 97, the LC region shifts towards higher water content and the L₂ region is extended to the area of lower IPM concentration, meanwhile the I phase disappears. By analyzing the shear rate (η_γ=0.1) and yield stress (σ₀), adding IPM to lecithin solutions increases the values of η_γ=0.1 and σ₀, and after further adding Brij 97, the η_γ=0.1 and σ₀ decrease dramatically. Notably, different from the lecithin/DDAB/water system studied by Youssry and Montalvo, in lecithin/Brij 97/IPM/H₂O system, at the relatively higher water content area of the LC phase, the water content has little effect on the critical stress. It is also found that the change of dynamic storage modulus (G′) is similar with that of η_γ=0.1 and σ₀ parameters when adding IPM and Brij 97. Maxwell model fitting results show that in the LC phase, the relaxation of the water molecule is prolonged by adding IPM and Brij 97 to lecithin solutions.     

Effect of Potassium Oleate on Rheological Behavior of Cationic Guar in Aqueous Solution with Varying Temperatures

The rheology of the cationic guar (CG) solution was measured and the effects of potassium oleate (KOA) upon the rheological properties of CG solution were studied. The steady shear viscosity measurement has shown that the viscosity of CG solution increased dramatically in the presence of KOA. The viscosity enhancement of KOA upon CG solution can be approximate three orders in magnitude. The gel-like formation of CG solution is observed at the high concentration of KOA. The excess addition of KOA results in the phase separation of CG solution. The oscillatory rheological measurement has shown that the crossover modulus Gc (corresponding to either storage modulus G′ or loss modulus G″ at the frequency w_c where G′ equals G″) for CG solution, decreases with the increasing the concentration of KOA in solution. On the other hand, the apparent relaxation time τ_app (=1/w_c) increases with increasing the concentration of KOA in solution. Our experimental results suggest that for surfactant such as KOA which has a stronger tendency to form micelles in solution, the cooperative hydrophobic interaction of polymer bound to surfactants is less necessary to the formation of aggregates in solution, especially at the high concentration of surfactants. In fact, with the increase of the concentration of KOA, the number of the aggregates which associate polymer together decreases whereas the intensity of these aggregates increases. The effect of temperature upon the aggregation is also significant. With the increase of temperature, the number of the aggregates increases whereas the intensity of these aggregates decreases, probably because the ionization of KOA increases at high temperature.     

电响应聚合物薄膜的表面图案化

研究了炭黑(CB)和石墨(GP)填充高密度聚乙烯(HDPE)复合体系的动态流变行为.发现高填料含量时出现似固体行为,并认为它归因于无机粒子网络逾渗结构的形成.在相同聚合物基体条件下,粒子种类和粒子几何参数(粒子形状、大小、粒径分布)对低频区域流变行为、流变参数的逾渗行为和逾渗阈值(φc)有决定性影响,且种类的影响相比于粒子几何参数更为显著.此外,高表面活性及高比表面积(大径厚比、小尺寸)粒子填充体系具有较低的φc.     

Rheological Behavior of the Melts for Polyethylene-based Montmorillonite Nanocomposites

IntroductionOwing to their special structures or morphologies,polymer-based montmorillonite nanocomposites exhibitsome particular characteristics,such as,physical,thermal,and mechanical properties,induced by theaddition of very small amounts of inorganic …     

十二烷基硫酸钠对聚乙烯醇亚浓水溶液流变行为的影响

表面活性剂会影响聚乙烯醇(PVA)分子间及分子内氢键形成,进而改变其水溶液的流变响应.本文在确定十二烷基硫酸钠(SDS)在PVA亚浓水溶液中的临界聚集浓度(CAC)和临界胶束浓度(CMCP)基础上,考察了SDS对PVA亚浓溶液(10 wt%)流变行为的影响.研究发现,不同浓度SDScsur对PVA水溶液稳态流变行为的影响差异较大:(1)当csur CMCP,随着csur增加,胶束起物理交联点作用,ηa增大,复合溶液的动态储能模量亦显著增大.加入SDS后,PVA体系内结合水的数目降低,但当csur> CMC后,结合水的数目几乎不变,黏流活化能也表现出相近的变化规律.与稀溶液相比,SDS对PVA亚浓溶液的降黏幅度较大.     

粒子填充HDPE复合体系动态流变行为研究

研究了炭黑(CB)和石墨(GP)填充高密度聚乙烯(HDPE)复合体系的动态流变行为.发现高填料含量时出现似固体行为,并认为它归因于无机粒子网络逾渗结构的形成.在相同聚合物基体条件下,粒子种类和粒子几何参数(粒子形状、大小、粒径分布)对低频区域流变行为、流变参数的逾渗行为和逾渗阈值(φ_c)有决定性影响,且种类的影响相比于粒子几何参数更为显著.此外,高表面活性及高比表面积(大径厚比、小尺寸)粒子填充体系具有较低的φ_c.