聚合物熔体延伸粘度的研究方法

聚合物熔体的延伸粘度是影响聚合物熔体流动特性和成型制品性能的重要因素。本文较为系统地介绍了聚合物熔体延伸粘度的理论和实验研究方法,着重介绍了Cogswell、Gibson、Binding和Berstered等人的理论研究工作,为进一步研究熔体的延伸粘度提供思路。     

注入工艺对聚合物粘度损失的影响

在三次采油过程中,聚合物驱是油田增油降水的主要手段,对聚合物驱发效果起主要做用的是聚合物溶液的流体粘度与地下原油粘度的合理比值范围。当分子量和注入浓度定时,注入工艺等各项条件的变化,明显影响注入流体的粘度和聚驱的发效果。因此从地面配制注入体系源头上提高聚合物的粘度保留率,对降低聚合物干粉用量,保证聚合物驱发效果有重大意义。     

聚合物水溶液初始粘度影响因素研究

聚合物分子量和注入浓度一定时,注入工艺、水质和油层温度等各项条件的变化,明显影响注入流体的粘度和聚驱的开发效果。在特定聚合物和一定的注聚工艺情况下,通过对注入污水的水质处理,降低矿化度含量,一定程度可提高聚合物溶液粘度,在降低聚合物用量的同时,更有利于改善聚合物溶液的驱油效果。因此深入研究聚合物水溶液初始粘度的影响因素,从地面配制注入体系源头上提高聚合物的粘度保留率,对降低聚合物干粉用量,保证聚合物驱开发效果有重大意义。     

聚合物溶液粘度影响因素研究

本文对影响了聚合物溶液粘度的pH值、温度、金属阳离子、搅拌速度和时间等不同因素做了研究。对以上因素进行了室内试验分析,并确定了现场配制时应控制的主要指标范围:pH值应控制在6～9,温度以15～30℃为宜,并且应当尽量用矿化度较低的清水配制,配制时搅拌速度应控制在150r/min以下,搅拌时间不应超过3h。     

杀菌剂对含聚污水配制聚合物粘度影响研究

针对含聚污水中细菌含量高,直接配制聚合物粘度稳定性差的问题,开展了在含聚污水中加入杀菌剂后配制聚合物研究,实验结果表明,高浓GNSJ-01杀菌剂杀菌效果好于SJYJ杀菌剂和高浓GNSJ-02杀菌剂,且杀菌剂浓度用量最低,是较为经济有效的杀菌剂。     

聚合物溶液粘度的主要影响因素分析

聚合物驱是一种重要的三次采油技术，该技术用聚合物水溶液为驱油剂，以增加注入水的粘度，提高其波及效率，从而达到提高原油采收率的目的。众所周知，配制的聚合物溶液的粘度越高，其波及面积越大，驱油效果也就越理想。     

聚合物溶液粘度影响因素研究

本文主要针对孤岛油田现场应用的聚合物及配制注入过程中,聚合物溶液粘度的主要影响因素进行分析和研究,探讨了控制粘度降解的方法,从而为现场注入和提高聚驱效果提供依据。     

污水水质对聚合物溶液粘度影响

体系粘度是化学驱体系发挥波及效果最重要的性能之一,在矿场应用中,配制用水水质是影响聚合物溶液粘度的重要因素甚至是决定因素。综述了水质中影响聚合物溶液粘度的因素,分析了各个因素的影响程度、影响机理,按照影响程度级别对影响因素进行了分类,最终给出了建议的水质控制项目及指标上限,为化学驱现场改善水质、保证体系粘度提供参考。     

配聚污水对聚合物溶液粘度影响及对策

为了更好的揭示配聚污水对聚合物溶液粘度的影响规律,利用布氏粘度仪对不同污水配制聚合物溶液粘度进行测定。研究结果表明:聚合物溶液粘度随着金属阳离子浓度的增加而迅速下降后下降平缓。特别是Mg~(2+)、Ca~(2+)浓度对聚合物溶液粘度具有较大影响,较小浓度的提升就能引起HPAM溶液粘度的大幅度下降。选择Na_2C_2O_4作为提高HPAM溶液粘度的络合剂,质量浓度为1 500 mg/L的HPAM溶液增粘率达到增粘率达到33.2%。     

粘度法测定聚合物的平均分子量

本文介绍了粘度法测定聚合物分子量的几种方法,重点介绍了外推法,同时也介绍了几种快速、方便的单点法。并将外推法同单点法进行了比较。     

Apparent elongational viscosity of dilute polymer solutions

Apparent elongational viscosity studies were made on dilute solutions of high molecular weight polymers using a fiber spinning apparatus designed for low shear viscosity liquids with substantial elongational effects. The experimental method involved the flow of solutions of polyacrylamide and poly(ethylene oxide) from a tube into an evacuated vessel. Experimental results showed that the apparent elongational viscosity obtained from the jet shape increased linearly with the stretch rate.     

高固含量聚合物乳液黏度的影响因素

综述了乳液粒径及分布、乳化剂、引发剂、单体配比、反应温度、功能单体、pH值等对聚合物黏度的影响，确定了实现高固含量低黏度乳液的最佳条件。     

Effect of hydrogen donors on polymer degradation

The thermal decomposition of hydrocarbon macromolecules, including polymers in solution, is influenced by the presence of hydrogen donors. Depending on the particular polymer, hydrogen donors may increase, decrease, or have no effect on degradation rate. We investigated the concentration effect of the hydrogen- (H-)donor, 6-hydroxy tetralin, on degradation of polystyrene (2 g/l) dissolved in mineral oil at 275°C. The time evolution of the molecular weight distribution (MWD) was determined by gel permeation chromatography of samples from the batch reactor. The data indicated that the H-donor decreases the polystyrene degradation rate. This is in contrast to the H-donor (tetralin) enhancement of degradation for poly(styrene–allyl alcohol) dissolved in a 1-butanol solution at 150°C. Because the reaction mechanism for polymer degradation involves radicals, we have developed continuous-distribution mass balances for polymers and radicals in the elementary reactions by treating molecular weight as a continuous variable. Based on reactions for initiation–termination, propagation–depropagation and H-abstraction, the model describes the various H-donor effects through relative values of rate coefficients.     

Improved method to calculate Hansen solubility parameters of a polymer

An improved method to calculate Hansen solubility parameters δ_d, δ_p and δ_h, as well as the radius of interaction sphere for a given polymer is presented, starting from the idea that the solvents which dissolve a polymer, form in the interior of its solubility range a system of material points, their ‘masses' being given by the unity normed intrinsic viscosities of the polymer in the considered solvents. The mass centre coordinates of the material points system represent in fact Hansen solubility parameters of the polymer, and the radius of interaction sphere the distance from this centre to the farthest point of material points system mentioned.     

Macrostructural design of highly porous SiOC ceramic foams by preceramic polymer viscosity tailoring

Highly porous SiOC ceramic foams with gradient or uniform macrostructures were obtained through polymer derived ceramic routes. Precuring of preceramic polymers and introduction of SiO₂ powders were used to tailor precursor viscosity and hence SiOC foam macrostructure. Effects of polymer viscosity on porosity, pore size, pore distribution were investigated by light microscopy and micro-computed tomography techniques. SiOC ceramic foams. Foams from one unmodified precursor, showed pore size gradient with small pores located at bottom and large pores at the top. To address this non-uniformity, the viscosity of the precursor was increased by pre-curing the preceramic polymer, which resulted in decrease of the average pore size and improvement in pore size uniformity. For a different system with a self-foaming preceramic polymer, because of the simultaneous release of foaming gases and rapid increase in viscosity during crosslinking, the foam had non-uniform macrostructure with large pores and thick struts at the bottom. By addition of SiO₂ fillers, the crosslinking reaction rate was reduced leading to homogeneous pore nucleation and uniform small pore size foams.     

Process simulation using the expanded fluid model for viscosity calculations

The expanded fluid (EF) viscosity model was implemented and further developed for efficient integration into a commercial process simulator (VMGSim™). The model has three adjustable parameters per component and its inputs are density, pressure and low pressure gas viscosity. The model was adapted to use densities determined by the Rackett correlation (liquid phase) and the Advanced Peng–Robinson Equation of State (vapor phase). The enhanced EF model fit experimental viscosities of pure hydrocarbons, water and polar compounds important for the simulation of oil and natural gas systems with average absolute errors just above 5%. The implemented EF model was tested against experimental viscosity data that included hydrocarbon and aqueous mixtures with average absolutes errors of 0.7 and 6.2% respectively. Generalized expressions for the estimation interaction parameters of binary mixtures involving paraffins, naphthenes, aromatics, alcohols, glycols and water were obtained. The EF model was also applied to crude oil (bitumen) examples. The three key developments for the efficient implementation of the EF model in a commercial simulator were: (1) the appropriate selection of phase density models; (2) the automatic determination of model fluid specific parameters; and (3) the use of generalized mixing rules for the calculation of binary interaction parameters.     

Towards the simulation of poly(vinyl phenol)/poly(vinyl methyl ether) blends by atomistic molecular modelling

Molecular simulations of poly(vinyl phenol)/poly(vinyl methyl ether) (PVPh/PVME) blends were performed and their degree of miscibility evaluated as a preliminary step before orientation simulations. A minimum of three periodic boundary condition amorphous models was constructed and analysed in terms of solubility parameter, X-ray pattern, pair correlation function, hydrogen bond fraction and backbone conformation. The values obtained are consistent with miscibility of the systems, although it is suggested that the degree of mixing is not uniform for the different models.     

Composition-dependent dynamics in miscible polymer blends: influence of intermolecular hydrogen bonding

Dynamics of the miscible blend of poly(vinyl methyl ether) and poly(4-vinylphenol) [PVME/PVPh] have been studied using broadband dielectric relaxation spectroscopy (DRS). The results are compared with those reported for PVME/polystyrene [PS] and PVME/poly(2-chlorostyrene) [P2CS] blends to examine the effect of intermolecular hydrogen bonding. These blends have similar chemical structures, with the exception that strong intermolecular hydrogen bonds are formed between PVME and PVPh. Whereas PVME and P2CS (or PS) relax individually in their blends due to intrinsic mobility differences and the absence of strong intermolecular interactions, the segmental relaxations of PVPh and PVME are coupled in the blends controlled by intermolecular hydrogen bonding. Dynamic heterogeneity was observed in PVPh/PVME blends with PVPh concentration higher than 50%. This is due to the decoupling arising from the strong intramolecular hydrogen bonding between PVPh segments. Finally, in the blend, the secondary relaxation processes of both components occur at approximately the same temperature-frequency location as those in corresponding neat polymers, but with much lower intensity, suggesting suppression by the intermolecular hydrogen bonding. Our results suggest that the composition-dependent dynamics in PVPh/PVME are even more complicated than that observed in blends without strong intermolecular interactions.