增黏剂氟化丙烯酸酯-苯乙烯在超临界CO_2压裂液中的流变特性及增黏机制

针对超临界CO_2压裂中CO_2流体粘度低、携砂困难、储层压裂施工规模受限等问题,开展了超临界CO_2压裂液增黏剂氟化丙烯酸酯-苯乙烯的研究。分析了该增黏剂的分子结构特征,探讨了该增黏剂在超临界CO_2中的增黏机制,研究了在不同剪切速率、温度、压力及增黏剂注入量下增黏剂在超临界CO_2中的流变特性。结果表明,将氟化丙烯酸酯与苯乙烯按质量浓度0.71∶0.29进行配比,可合成含有两个单体结构的无规共聚物氟化丙烯酸酯-苯乙烯,其产率为93.9%,分子量为71 400 g/mol,粘度值为62.4 mPa·s。应用该增黏剂的超临界CO_2的压裂液粘度值可达17.834 mPa·s以上,使超临界CO_2粘度提高两个数量级(148～321倍)。加入增粘剂的压裂液体系既有非牛顿流体的流动特性及假塑型流体的剪切特性;同时其粘度还随增黏剂注入量的增加呈先升后降的趋势;温度低于55℃、压力低于14 MPa时,压裂液体系粘度变化主要受压力的影响;但当温度高于55℃、压力高于14 MPa时,则温度影响占主导地位。该研究为超临界CO_2压裂液增黏剂的研制及筛选提供了有效的技术思路,对超临界CO_2压裂研究具有一定的实用性。     

利用KH560和纳米SiO2采用“一步法”反应挤出增黏PET

以KH560（3-缩水甘油基氧基丙基三甲氧基硅烷）和纳米SiO₂颗粒复配作为扩链剂，采用“一步法”反应挤出增黏聚对苯二甲酸乙二醇酯（PET）。KH560和SiO₂的添加量均为PET质量分数的2.5%时，增黏效果最好。并且在PET不干燥的情况下，KH560和SiO₂复配也可增加PET的黏度，可用作PET的扩链剂和防水解剂。经透射电镜观察，发现SiO₂在PET中的分散状况良好。用FTIR研究了KH560、SiO₂、PET三者之间的反应机理。用TGA分析了SiO₂的接枝率，发现接枝率高达72.0%。用DSC对PET/纳米SiO₂复合材料的结晶行为进行了研究，并讨论了结晶行为对力学性能的影响。当KH560和SiO₂的添加量均为PET质量分数的2.5%时，结晶度最低，综合力学性能最好。     

胶黏剂未来几年发展目标已确定

未来5年,我国将重点发展环保型、节能型胶黏剂,同时还将大力研究开发和发展高技术含量、高附加值、高性能的胶黏剂新产品。主要包括:水性聚氨酯胶黏剂、水性氯丁橡胶型胶黏剂、高性能和高品质压敏胶及制品、VAE(乙酸乙烯酯-乙烯)乳液、EVA(乙烯-乙酸乙烯酯)树脂、SIS(苯乙烯-异     

聚表剂乳化增黏特性研究

为优化N试验区聚表剂驱合理注入参数,开展了聚表剂乳化增黏特性研究。聚表剂浓度大于1200mg/L时,黏度增幅可达到50%;尽管聚表剂从配制到井口沿程黏损达到60%以上,注入黏度仅为2.0mPa.s,但聚表剂与原油乳化后形成的乳状液黏度增大2倍以上,见效井采出液乳化明显,增油降水效果显著。通过统计分析室内和现场试验的动、静态数据,绘制了聚表剂乳化强度与药剂浓度及含水的关系图版,为现场试验聚表剂注入浓度设计提供了参考依据。     

抗水性和抗冻性聚乙酸乙烯酯乳液胶黏剂的制备

用乙烯-乙酸乙烯酯共聚乳液作为种子进行聚合，制备了抗水性和抗冻性的聚乙酸乙烯酯乳液胶黏剂。研究了乙烯-乙酸乙烯酯共聚物乳液的用量对改进型PVAC乳液的抗冻性、抗水性及表面张力的影响。     

低渗储层干法加砂压裂增黏剂的研发及压裂液体系优选

针对长庆气田原采用水基压裂液存在的问题,首次采用分子模拟技术,开展高聚物分子设计和增黏效果模拟,开发出了针对二氧化碳干法加砂压裂施工专用增黏剂。通过室内试验及数学模型分析,优选出5%增黏剂+95%液态二氧化碳作为压裂液体系,大大提高了液态二氧化碳携砂性能。该工艺在长庆气田开展现场试验,并通过微地震监测评价储层改造效果,试验井微地震监测裂缝半长81~113 m,裂缝高度57 m。现场初步试验结果表明:二氧化碳干法加砂压裂技术对低渗、强水锁储层具有较好的改造效果,同储层条件下,裂缝长度达到常规水力压裂改造的2倍;排液速度快,完井周期是常规水基压裂的三分之一,储层伤害低,单井产量可增加2~3倍,储层改造效果良好。研究和应用结果可以为类似低渗储层增产改造提供技术参考。     

钴卟啉-四丁基溴化铵串联催化苯乙烯在氧气和二氧化碳中合成碳酸苯乙烯酯

通过仿生催化，将苯乙烯、氧气（O₂）和二氧化碳（CO₂）直接合成环状碳酸酯在现代化学中极具学术研究意义和工业应用价值。采用钴卟啉-四丁基溴化铵为双组分催化剂，以2-氧代环戊烷羧酸甲酯为助剂，在O₂和CO₂条件下，直接将苯乙烯转化为碳酸苯乙烯酯。系统考察了催化剂用量等因素对催化性能的影响。在最佳反应条件下，苯乙烯的转化率高达99%，环状碳酸酯的收率可达35%。利用在线紫外与在线红外探讨了该串联反应可能的机理。结果表明，钴中心与2-氧代环戊烷羧酸甲酯的环内氧原子配位后活化氧气形成过氧活性物种，进而形成高价钴-氧中间体，其通过传递氧原子给苯乙烯而生成环氧苯乙烷。而后，环氧苯乙烷在四丁基溴化铵的催化作用下开环，并通过CO₂插入反应和分子内闭环反应最终生成环状碳酸酯。     

PHBV扩链改性及其发泡行为研究

以乙烯⁃甲基丙烯酸缩水甘油酯共聚物（CE）为扩链剂与聚（3?羟基丁酸酯?co?3?羟基戊酸酯）（PHBV）进行熔融共混,制备了扩链PHBV样品,然后采用超临界CO₂（scCO₂）釜压发泡法将其在160 ℃、20 MPa下进行物理发泡,成功制备了不同PHBV泡沫。结果表明,与常压差示扫描量热法相比,采用高压差示扫描量热法测量的各组PHBV的结晶温度和熔融温度略微下降;CE的加入提高了PHBV样品的复数黏度（G'）和储能模量（η^* ）;随着CE含量的增加,PHBV发泡样品的泡孔密度和发泡倍率逐渐增加,泡孔尺寸逐渐减小。     

胶黏剂对芳纶复合材料防刺性能的影响

以不同的水性聚氨酯(PU)及环氧树脂(EP)为主体,制得一系列胶黏剂胶液,并制备成胶膜,通过分析胶膜的力学性能及硬度优选出胶黏剂主体;采用胶黏剂胶液、助剂、纳米二氧化硅(SiO₂)粒子与芳纶1414通过热压法制备芳纶复合材料,研究了助剂含量、纳米SiO₂含量和上胶量对复合材料防刺性能的影响。结果表明：由相对分子质量为2 000的聚己二酸丁二醇酯二醇合成的PU作为胶黏剂主体,制备的复合材料具有良好的综合性能,其抵御功(η_p10)可达0.264 (mN·m³)/g;复合材料的η_p10随胶黏剂中助剂含量的增加呈现先增大后降低的趋势,随着上胶量的增加而增大;以PU为胶黏剂主体、助剂质量分数为1.8%、上胶量为27%时,复合材料的η_p10达0.288 (mN·m³)/g,兼具良好的防刺性能和轻量化;在胶黏剂中添加适量的纳米SiO₂可进一步提高复合材料的防刺性能,当胶黏剂中纳米SiO₂质量分数为6%时,...     

环氧扩链剂的合成及其反应挤出增黏回收PET的研究

采用乳液聚合方法合成了环氧类扩链剂ECP-苯乙烯-丙烯酸的共聚物ESA,并对其进行了红外表征。将ESA应用于回收聚对苯二甲酸乙二醇酯(PET)进行反应挤出扩链,能够提高回收PET的分子量和特性黏度,降低羧基含量,扩链效果明显。挤出工艺的研究表明,在挤出温度为260℃,挤出时间为4～6 min时,扩链剂达到最大挤出增黏效果。     

Measurement and correlation of supercritical CO2 and ionic liquid systems for design of advanced unit operations

Ionicliquids combined with supercritical fluid technology hold great promise as working solvents for developing compact processes. Ionic liquids, which are organic molten salts, typically have extremely low volatility and high functionality, but possess high viscosities, surface tensions and low diffusion coefficients, which can limit their applicability. CO₂, on the other hand, especially in its supercritical state, is a green solvent that can be used advantageously when combined with the ionic liquid to provide viscosity and surface tension reduction and to promote mass transfer. The solubility of CO₂ in the ionic liquid is key to estimating the important physical properties that include partition coefficients, viscosities, densities, interfacial tensions, thermal conductivities and heat capacities needed in contactor design. In this work, we examine a subset of available high pressure pure component ionic liquid PVT data and high pressure CO₂ - ionic liquid solubility data and report new correlations for CO₂-ionic liquid systems with equations of state that have some industrial applications including: (1) general, (2) fuel desulfurization, (3) CO₂ capture, and (4) chiral separation. New measurements of solubility data for the CO₂ and 1-butyl-3-methylimidazolium octyl sulfate, [bmim][OcSO₄] system are reported and correlated. In the correlation of the CO₂ ionic liquid phase behavior, the Peng-Robinson and the Sanchez-Lacombe equations of state were considered and are compared. It is shown that excellent correlation of CO₂ solubility can be obtained with either equation and they share some common characteristics regarding interaction parameters. In the Sanchez-Lacombe equation, parameters that are derived from the supercritical region were found to be important for obtaining good correlation of the CO₂-ionic liquid solubility data.     

Prediction of the viscosity reduction due to dissolved CO2 of and an elementary approach in the supercritical CO2 assisted continuous particle production of a polyester resin

The dissolution of CO₂ in a polymer causes plasticization of the polymer and hence, its viscosity is reduced. A model based on the free volume theory has been used for a polyester resin, which shows a considerable reduction in the viscosity due to dissolved CO₂. Therefore, supercritical CO₂ has been used as a processing solvent in the continuous production of micron size particles of the resin. Despite the viscosity reduction caused by the dissolved CO₂, an excess quantity of CO₂ with respect to its solubility limit has been used for micronisation of the polymer due to its high viscosity. The mixing of CO₂ and the polymer has not been possible in an extruder at high gas to polymer mass ratios and consequently, a simplified Kenics type static mixer has been used for the mixing purpose. In this study, the effect of various parameters such as temperature, pressure, nozzle diameter and gas to polymer mass ratio on the particle morphology and size has been studied. The experimental results manifest the technological as well as the theoretical insight into the particles production from a high viscosity material.     

Micellar catalysis for partial oxidation of toluene to benzoic acid in supercritical CO2: effects of fluorinated surfactants

One of the key hindrances on development of solid catalysts containing cobalt species for partial oxidation of organic molecules at mild conditions in conventional liquid phase is the severe metal leaching. The leached soluble Co species with a higher degree of freedom always out-performs those of solid supported Co species in oxidation catalysis. However, the homogeneous Co species concomitantly introduces separation problems. We have recently reported for the first time, a new oxidation catalyst system for the oxidation of organic molecules in supercritical CO₂ using the principle of micellar catalysis. [CF₃(CF₂)₈COO]₂Co·xH₂O (the fluorinated anionic moiety forms aqueous reverse micelles carrying water-soluble Co²⁺ cations in scCO₂) was previously shown to be extremely active for the oxidation of toluene in the presence of sodium bromide in water–CO₂ mixture, giving 98% conversion and 99% selectivity to benzoic acid at 120 °C. In this study, we show that the effects of varying the type of surfactant counterions and the length of the surfactant chains on catalysis. It is found that the use of [CF₃(CF₂)₈COO]₂Mg·yH₂O/Co(II) acetate is as effective as the [CF₃(CF₂)₈COO]₂Co·xH₂O and the fluorinated chain length used has a subtle effect on the catalytic rate measured. It is also demonstrated that this new type of micellar catalyst in scCO₂ can be easily separated via CO₂ depressurisation and be reused without noticeable deactivation.     

超临界二氧化碳-共溶剂体系与聚醋酸乙烯酯相互作用

采用多尺度模拟和实验结合研究了乙醇、丙酮、正庚烷等共溶剂的加入对超临界二氧化碳（CO₂）溶剂体系的影响,通过改善溶剂-溶剂和溶剂-溶质相互作用增强聚醋酸乙烯酯（PVAc）与CO₂的相容性。量子力学从头算结果表明,3种共溶剂中乙醇与CO₂的相互作用最强,丙酮次之,正庚烷最弱。分子动力学模拟也表明在相同共溶剂含量下,乙醇对溶剂体系溶解度参数的改善最为明显,超临界CO₂-乙醇体系与PVAc链的相互作用更强,有助于提高PVAc与溶剂的相容性。这是由于乙醇本身的溶解度参数较大,且与CO₂形成氢键作用,从而大幅增强了其与CO₂的相互作用。浊点压力实验证实了共溶剂的加入增强了超临界CO₂体系与PVAc的相容性,乙醇的加入对PVAc浊点压力的降低最为有效,且随着共溶剂含量的增加,PVAc在溶剂中的溶解能力增强。     

CO2在PPO和PS共混物中的溶解与扩散行为研究

以超临界CO₂为发泡剂,采用质量衰减法测试发泡剂在聚苯醚（PPO）/聚苯乙烯（PS）中的溶解扩散性,在静态条件下系统研究了工艺参数及PPO/PS组成对CO₂溶解度与扩散系数的影响,建立了温度、压力及PPO含量与CO₂溶解度的定量关系。结果表明,CO₂在PPO/PS中的溶解度随着PPO含量的增加而增加,随着压力的增加和温度的降低而增大;扩散系数随着PPO含量的增加而减小,随着温度的升高和饱和压力的增大而增大。     

基于多变量摄动的超临界CO2干气密封动态特性

超临界CO₂压缩机进口端干气密封工况处于临界点附近,强非线性物性及高Reynolds数流动使其密封特性异于常规介质干气密封。在综合考虑四种实际流体效应的稳态膜压求解模型基础上,基于摄动法推导了包括膜压、密度、黏度、Reynolds数、湍流系数和惯性系数在内的多变量摄动干气密封动特性数值模型。对比分析了超临界CO₂和N₂干气密封的动态特性,研究了不同频率比下各实际流体效应和变量摄动形式对超临界CO₂干气密封动特性系数的影响规律,获得了不同条件下动态特性的关键影响因素。结果表明：高频下超临界CO₂干气密封的刚度和阻尼系数较N₂干气密封降幅超过50%,湍流效应和实际气体效应对干气密封动态特性影响显著,低频下采用经典变量摄动和忽略湍流系数摄动会使动特性系数计算偏差很大,而高频下经典变量摄动模型对刚度系数的预测精度可接受。     

多孔介质内超临界CO2流体及泡沫驱油特性的比较实验研究

CO₂混相驱替可以提高原油采收率,因此近年来得到研究者们的广泛关注。使用高温高压驱替设备,利用超临界CO₂流体、超临界CO₂泡沫及N₂泡沫作为驱替介质,对油水饱和孔隙介质中的油相驱替特性开展了比较实验研究。通过对驱替过程沿程压力及对驱替增采油量的测量,对不同驱替手段在孔隙介质内的油相增采特性进行深入研究和探讨。研究发现在温度为50℃、压力为13 MPa时,超临界CO₂流体对多孔介质内的油相驱替效果有显著提升,当压力进一步升高到23 MPa时,油相增采效果不明显。说明在本实验条件下超临界CO₂流体与油相在50℃、13 MPa时可达到混相驱替状态;而采用超临界CO₂泡沫及N₂泡沫注入工艺未能进一步提高出油量。沿程压差测量结果则显示,与N₂泡沫相比,超临界CO₂泡沫在多孔介质试样内的驱替压差较小,起泡性能较差。实验结果对于筛选及评价超临界CO₂驱油工艺具有一定的指导意义。     

离子液体支撑液膜的CO2/CH4分离性能

由于离子液体对CO₂具有较好的溶解选择性,离子液体支撑液膜分离CO₂越来越受到关注。比较了含3种不同阴离子的常规离子液体([bmim][BF₄]、[bmim][PF₆]、[bmim][Tf₂N])作为支撑液膜的液膜相分离CO₂/CH₄的性能,考察了咪唑环上烷基链长对离子液体支撑液膜性能的影响。考虑向离子液体中引入胺基和羧基等亲CO₂基团,制备了1-丁基-3-甲基咪唑丙氨酸离子液体([bmim][β-Ala]),考察了 [bmim][β-Ala]支撑液膜分离CO₂/CH₄的性能,并对在CO₂渗透测试前后的支撑液膜进行了FT-IR分析,发现氨基酸离子液体中的-NH₂和CO₂的较强作用以及该离子液体的高黏性影响了CO₂的透过性,使[Bmim][β-Ala]支撑液膜的CO₂透过率低。     

CO2在醚酯溶剂中的溶解度测定及热力学计算

采用恒定容积法,在温度353.15、363.15、373.15 K下,测定了CO₂在丙二醇甲醚醋酸酯(PMA)、二丙二醇甲醚醋酸酯(DPMA)、乙二醇丁醚醋酸酯(BAC)以及乙二醇苯醚醋酸酯(EPA)中的溶解度数据,压力最高可达11.73 MPa。结果表明CO₂在醚酯体系中溶解度受温度、压强的影响较大,压强一定时,CO₂在醚酯中溶解度随温度升高而减小;温度一定时,随着压强增大而增大;相同条件下,CO₂在四种醚酯中溶解度大小为PMA＜ EPA＜BAC＜DPMA。通过变形Clausius - Clapeyron方程,计算得到CO₂在醚酯溶剂中的Gibbs自由能Δ_sol G,溶解焓变Δ_sol H和熵变 Δ_sol S等热力学性质,从宏观热运动角度进一步解释了CO₂的溶解机理,为开发新型CO₂物理吸收剂提供理论支撑。     

Polydimethylsiloxane assisted supercritical CO2 foaming behavior of high melt strength polypropylene grafted with styrene

Foamable high melt strength polypropylene (HMSPP) was prepared by grafting styrene (St) onto polypropylene (PP) and simultaneously introducing polydimethylsiloxane (PDMS) through?a?one-step?melt extrusion process. The effect of PDMS viscosity on the foaming behavior of HMSPP was systematically investigated using supercritical CO₂ as the foaming agent. The results show that the addition of PDMS has little effect on the grafting reaction of St and HMSPP exhibits enhanced elastic response and obvious strain hardening effect. Though the CO₂ solubility of HMSPP with PDMS (PDMS-HMSPP) is lower than that of HMSPP without PDMS, especially for PDMS with low viscosity, the PDMS-HMSPP foams exhibit narrow cell size distribution and high cell density. The fracture morphology of PDMS-HMSPP shows that PDMS with low viscosity disperses more easily and uniformly in HMSPP matrix, leading to form small domains during the extrusion process. These small domains act as bubble nucleation sites and thus may be responsible for the improved foaming performance of HMSPP.