支化结构对树枝状聚合物溶液剪切前后流变性能的影响

采用吴茵混调器模拟聚合物在其配制、输送、注入中的机械剪切作用,研究了不同支化程度对剪切前后的驱油用树枝状聚合物溶液的流变性能的影响。首先制备了3种不同支化程度的树枝状聚合物,研究了剪切前后的树枝状聚合物的分子链粒径分布和分子量大小,然后研究了不同因素对树枝状聚合物流变性能的影响并考察了树枝状聚合物溶液的黏弹性能,最后结合环境扫描电镜分析支化结构对剪切前后树枝状聚合物溶液的流变性能的影响。结果表明：支化程度高的树枝状聚合物具有更大的流体力学半径和分子量,受环境影响较小;树枝状聚合物溶液呈现假塑性流体特征,支化程度越高,剪切前后的聚合物溶液幂律指数n越小、稠度系数K越大;支化程度高的树枝状聚合物溶液支链间越容易发生缠结,形成致密、多层的空间网状结构,致使剪切前后的聚合物溶液的流变性能越好。     

氨基磺酸型两性表面活性剂在石英砂上的吸附

通过静态吸附实验,研究了6种氨基磺酸型两性表面活性剂在石英砂上的吸附,讨论了溶液浓度、表面活性剂疏水基链长、温度和pH对吸附量的影响.结果表明:氨基磺酸盐在石英砂上的吸附具有Langmuir吸附等温式的特点;温度升高使吸附量降低;等温下,溶液浓度低于临界胶束浓度(cmc)时,表面活性剂疏水基链长对吸附量的影响符合Traube规则,溶液浓度高于cmc,疏水基链长增加,吸附平台下降,且疏水基碳数和饱和吸附量Tmax间呈线性关系;溶液pH的变化会导致氨基磺酸型两性表面活性剂和石英砂表面电荷不同,静电作用使吸附量随体系的pH不同而发生变化.     

两亲聚合物在岩石矿物上的静态吸附研究

利用淀粉-碘化镉比色法测定了不同浓度两亲聚合物AP在岩石矿物上的静态吸附量,探讨了矿化度、温度和表面活性剂对其吸附的影响。结果表明,两亲聚合物的吸附等温线由L型和H型构成,存在一个最高吸附峰,具有多层吸附的特征;对于不同岩石矿物,两亲聚合物吸附量大小次序为粘土(Γmax为11.5 mg/g)>高岭土(Γmax为10 mg/g)>石英砂(Γmax为0.28 mg/g);两亲聚合物的吸附量随矿化度的增加先略微降低后又增大,随温度的升高增加;表面活性剂可降低两亲聚合物的吸附量。     

聚合物静态吸附研究

针对聚合物在流经油藏多孔介质时所发生的吸附滞留情况及其对驱油效果的影响,通过淀粉-碘化镉比色法对大庆油田杏十三区块聚合物进行静态吸附研究。根据聚合物浓度、温度、水解度以及相对分子量的变化分析对静态吸附量的影响,并得出两种不同类型吸附剂单位质量下对聚合物吸附的变化规律。研究表明,随着聚合物浓度的增加,单位质量的吸附量逐渐增大,而后趋于平缓,且与石英砂相比,聚合物在天然岩芯上的吸附量略大;通过加入氢氧化钠改变聚合物的水解度,聚合物的吸附量随水解度的增大先降低,而后略有回升,同时,随着相对分子量的增加,吸附量缓慢降低;且在一定范围内随着水浴温度的增加而逐渐下降。     

AP-P4/SDBS二元体系在石英砂上的吸附特性

针对AP-P4/SDBS聚表二元体系,选用不同浓度配方的聚表体系,在石英砂上展开静态吸附和动态滞留实验,研究聚表体系中各组分的吸附规律,考察了浓度、温度、矿化度对组分的吸附影响。结果表明,聚表二元体系中各组分在石英砂上的吸附符合Langmuir吸附模式,其中,SDBS表现为双分子层吸附、AP-P4表现为单分子层吸附特质。AP-P4与SDBS存在竞争吸附关系,SDBS的吸附量是AP-P4的20多倍。温度和矿化度升高,SDBS的吸附量增大。聚表二元体系中SDBS的动态滞留量小于其静态吸附量,而AP-P4的动态滞留量大于其静态吸附量。     

多孔介质中不同缔合能聚合物的吸附滞留研究

以疏水基含量分别为0.35%和0.2%的疏水缔合聚合物和常规线性聚丙烯酰胺为对象,研究聚合物缔合能力对吸附滞留特征的影响。采用浸泡法研究了不同浓度聚合物在石英砂上的静态吸附特征,并采用流动实验装置测定了浓度为1 500 mg/L的三种聚合物在不同速度下的动态滞留量。结果表明,疏水缔合聚合物呈现三段式的静态吸附特征,即先缓慢上升,达到临界缔合浓度后快速上升,最后趋于平稳;缔合能力越强,在临界缔合浓度之后的上升段幅度越大;缔合能力强的聚合物HAWP-0.35能够在3 mL/min的注入速度下与HPAM在0.5 mL/min具有相当的吸附滞留量,表明缔合能力能够克服注入速度对聚合物在多孔介质中动态滞留量的影响,缔合能力越强,吸附滞留量越大     

多孔介质中不同缔合能聚合物的吸附滞留研究

以疏水基含量分别为0.35%和0.2%的疏水缔合聚合物和常规线性聚丙烯酰胺为对象,研究聚合物缔合能力对吸附滞留特征的影响。采用浸泡法研究了不同浓度聚合物在石英砂上的静态吸附特征,并采用流动实验装置测定了浓度为1 500 mg/L的三种聚合物在不同速度下的动态滞留量。结果表明,疏水缔合聚合物呈现三段式的静态吸附特征,即先缓慢上升,达到临界缔合浓度后快速上升,最后趋于平稳;缔合能力越强,在临界缔合浓度之后的上升段幅度越大;缔合能力强的聚合物HAWP-0.35能够在3 mL/min的注入速度下与HPAM在0.5 mL/min具有相当的吸附滞留量,表明缔合能力能够克服注入速度对聚合物在多孔介质中动态滞留量的影响,缔合能力越强,吸附滞留量越大     

树枝状和超支化聚合物在废水处理中的研究进展

树枝状和超支化聚合物具有结构高度支化、内部有空穴、溶解性好、溶液黏度低、外端官能团易于修饰且密度高等优势,所以该类聚合物处理含各种污染物的废水有明显的优越之处。综述了近年来树枝状和超支化聚合物在处理含重金属离子废水、含油废水、染料废水中的研究进展。     

分光光度法测定十二烷基硫酸钠在石英砂上的静态吸附

利用甲基橙(MO)-溴化十六烷基吡啶(CPB)分光光度法测定十二烷基硫酸钠(SDS)在石英砂表面吸附后的浓度,得出静态吸附量。结果表明,用此法检测SDS的浓度是可行的,确定464 nm为测定波长,线性回归方程y=0.148 47x-0.008 56,R2=0.998 32。通过测定不同时间的吸附量,得出SDS在石英砂表面的吸附平衡时间为48 h。分别用模拟地层水和蒸馏水配制SDS溶液,确定了平衡吸附量分别为5.0 mg/g和1.8 mg/g,结果表明高矿化度导致了SDS在石英砂表面的大量吸附,并分析了模拟地层水条件下SDS在石英砂上的静态吸附不符合Langmuir模式的原因是SDS的脱附和沉淀再溶解。     

分光光度法测定十二烷基硫酸钠在石英砂上的静态吸附

利用甲基橙(MO)-溴化十六烷基吡啶(CPB)分光光度法测定十二烷基硫酸钠(SDS)在石英砂表面吸附后的浓度,得出静态吸附量。结果表明,用此法检测SDS的浓度是可行的,确定464 nm为测定波长,线性回归方程y=0.148 47x-0.008 56,R2=0.998 32。通过测定不同时间的吸附量,得出SDS在石英砂表面的吸附平衡时间为48 h。分别用模拟地层水和蒸馏水配制SDS溶液,确定了平衡吸附量分别为5.0 mg/g和1.8 mg/g,结果表明高矿化度导致了SDS在石英砂表面的大量吸附,并分析了模拟地层水条件下SDS在石英砂上的静态吸附不符合Langmuir模式的原因是SDS的脱附和沉淀再溶解。     

无机矿物对三元复合驱中聚合物吸附性能影响

三元复合驱过程中，聚合物会发生吸附现象，导致黏度降低，波及体积变小。研究了新疆油田三元复合驱实验中，无机矿物对聚合物吸附的影响因素。结果显示，对聚合物吸附最强的是蒙脱石，其次是绿泥石、伊利石，长石和石英砂最小；聚合物在松散岩心上的吸附大于胶结岩心上的吸附；随着渗透率的降低，聚合物的动态吸附量逐渐减小。与纯聚合物驱相比，三元复合驱中聚合物的黏度和吸附量要小的多，这主要是因为三元复合驱中高浓度的碱相当于增大了无机盐的浓度，压缩了聚合物导致吸附变小；而表面活性剂与聚合物产生了竞争吸附，降低了聚合物的吸附量。     

Concept of secondary heterogeneous structure of long-chain branched polyethylene

The mechanism of formation of surface roughness and extrusion swelling of the extrudate and the steady-shear viscous flow behavior in the region of high shear rate for branched polymers were investigated using two low-density polyethylenes and their sheared samples. These two polyethylenes varied in their degree of branching, molecular weight, and molecular weight distribution but were similar in their melt flow index. The effect of molecular parameters, especially long-chain branching, on viscoelastic properties in the molten state was also considered. Samples of various degree of shearing level were prepared by passing them repeatedly through an extruder. Results of intrinsic viscometry, gel permeation chromatography, and infrared spectroscopy of the original and the sheared samples indicate that no appreciable variation between them takes place in the molecular parameters during the process of extrusion shearing. Both surface roughness and extrusion swelling of the extrudate diminish with increase in the extent of shear. The extrusion shearing affects the surface roughness and extrusion swelling of the extrudate as well as the capillary entrance effect more markedly for the highly branched polymers with considerably higher molecular weight than for the less branched species with bell-type molecular weight distribution. These results demonstrate that heterogeneity becomes more conspicuous with the degree of long-chain branching level, and therefore the role of long-chain branching in the development of the heterogeneity is particularly important. It is suggested that the secondary heterogeneous structure arises through phase separation or from the heterogeneous formation of strongly entangled network at the branching point of the long-chain branching in the manufacturing process of the low-density polyethylene and that its presence causes the distinctive viscoelastic properties of long-chain branched polymer melts.     

The investigation of a new moderate water shutoff agent: Cationic polymer and anionic polymer

Cationic polymers and anionic polymers were selected as a moderate water shutoff agent for water production control. Due to the adsorption of polymers on the sand surface, the adsorption capacity under static condition, in porous media, and adsorption morphology on mica were investigated through starch–cadmium iodide method, core flow test, and atomic force microscopy measurement. The adsorption quantity on the sand surface increased with the high polymer concentrations and long adsorption time. With the increase of temperature and shearing time, the adsorption capacity slightly decreased. In addition, the adsorption capacity under water wettability condition was significantly larger than that under oil wettability condition. Alternate injection of cationic polymer and anionic polymer caused larger adsorption capacity in the core test. An adsorption multilayer was formed through alternate adsorption of cationic polymer and anionic polymer confirmed by atomic force microscopy. The visual simulation experiment was also conducted to illustrate adsorption and enhanced oil recovery mechanism. The polymers preferentially entered the high permeability zone and adsorbed on the sand surface, thus enhanced oil recovery. Furthermore, alternate injection of cationic and anionic polymers as a moderate water shutoff agent was successfully applied for water production control in oilfield test. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39462.     

甜菜碱型两性表面活性剂在高温高矿化度油藏条件下砂岩表面的吸附规律

利用紫外分光光度法测定了甜菜碱型两性离子表面活性剂在3种不同砂岩表面的吸附量,研究了甜菜碱型两性离子表面活性剂在胜利油藏环境下的吸附等温线,分别从吸附热力学和吸附动力学角度考察了两性离子表面活性剂在砂岩表面上的吸附规律,并对两性离子表面活性剂在石英砂、净砂、油砂表面吸附规律进行对比。结果表明,甜菜碱型两性离子表面活性剂在砂岩表面吸附符合Langmuir吸附规律,在石英砂上的吸附量最多,净砂次之,在油砂上的吸附量最少。温度由60～70℃的焓变小于温度为70～80℃的焓变,随温度升高影响趋势逐渐变小。Elovich方程能更好的描述吸附量随时间的变化关系。     

车用燃料电池质子交换膜的制备及性能

合成了一系列具有不同支化度的磺化聚芳醚砜材料,并对其结构和性能进行了表征。所制备的磺化的支化聚芳醚砜材料的分子量可达7.00×105以上,并且分子量分布在1.17左右,拉伸强度可达20.55~28.81 MPa。随着聚合物支化度的增加,聚合物的热稳定性得到改善,在550℃下的热失重可降低至39%~45%。高支化的磺化聚芳醚砜薄膜的氧化稳定性也得到改善,80℃下的使用寿命可提高至7.25 h。支化的磺化聚芳醚砜薄膜的吸水率和质子传导率都较高。80℃下高支化度的聚芳醚砜薄膜的质子传导率可达0.33 S/cm。对其微观形貌进行观测发现,支化聚芳醚砜中的支化结构可对周围的亲水磺酸基团起支撑作用,促使其发生团聚而形成连续的质子通道。     

Design,synthesis and polymerization of highly branched pseudodendrimers through tandem reactions

BACKGROUND: Pseudodendrimers are hyperbranched polymers which are isomeric with dendrimers, that is, each repeat unit is either fully reacted or only singly reacted. The careful design of an ABB′ monomer leads to higher branching by virtue of tandem reactions that increase the reactivity of linear units during polymerization, leading to fully reacted repeat units. The resulting polymers are predicted to be very highly branched, and in the optimum case, pseudodendrimers. RESULTS: Our work shows that 6‐amino‐3‐bromophthalide leads to a highly branched polymer via bromohydrin decomposition during polymerization, giving polymers of M? = of 3000 and a polydispersity index of 1.03. Our findings indicate a degree of branching of 0.84. The synthesis of similar polymers using different techniques confirms our proposed intermediate. CONCLUSION: We have demonstrated a new class of hyperbranched polymers which are highly branched, and may be considered pseudodendrimers. Copyright © 2009 Society of Chemical Industry     

The effects of branching and other physical properties of anionic polyacrylamides on the flocculation of domestic sewage

This investigation was undertaken to evaluate the effect of long-chain branching of anionic polyacrylamides on the flocculation of domestic sewage. The polyelectrolytes were polymerized using a redox couple, selectively hydrolyzed, and then characterized by means of light-scattering photometry. Coagulation tests were then employed to evaluate the synthesized polymers. The optimum polymer dose for suspended solids removal was used as the basis for evaluating each anionic polyacrylamide fraction with respect to its ability to flocculate domestic sewage. The results of this investigation indicated that as the weight-average molecular weight increased, the optimum polymer dose decreased. For polymers of similar molecular weights and differing radii of gyration, as the radius of gyration increased, the optimum polymer dose decreased, indicating that the “linear” polymers were more efficient in removing suspended solids than the “branched” polymers.     

Effect of microscopic aggregation behavior on polymer shear resistance

The study of polymer aggregation behavior effect on shear resistance shed light on the synthesis of antishear polymer for oil displacement and enhances the application effect of polymer flooding. The effects of mechanical degradation on the properties of polymer solutions were studied by using partially hydrolyzed polyacrylamide (HPAM), hydrophobically modified HPAM (HMPAM), and dendritic hydrophobic associative polymers (DHAP), which are characterized by “granular,” “chain,” and “cluster” aggregation behavior, respectively. The results show that mechanical shearing can dramatically reduce the performance of polymer solution. The shearing resistance can be effectively enhanced by improving the polymer aggregation behavior. After being strongly sheared, hydrophobically associating polymers can still partially restore its network through hydrophobic association, therefore rebuild the solution viscosity. For DHAP, the broken molecular chains distribute more evenly in solution after shearing. In addition, the strength of reconstructed network structure of DHAP is better than that of HMAPM, which implies a better shear resistance. Furthermore, the hydrophobic association of linear polymers will increase their static adsorption on quartz sand. Meanwhile, DHAP with stronger spatial structure has less static adsorption, which is beneficial to maintain a higher polymer concentration in solution. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48670.