黏弹性表面活性剂在煤粉上的吸附性能研究

采用紫外分光光度计研究了季铵盐型黏弹性表面活性剂VES-2-16和VES-4-16在沁水盆地煤粉上的吸附规律,并计算了该类表面活性剂在煤粉上的吸附焓。结果表明:季铵盐型黏弹性表面活性剂在煤粉上的吸附曲线符合Langmuir吸附规律;不管是在较高温度还是在较低温度下都基本能达到吸附平衡,此后吸附量的增加趋于平缓;两者在煤粉上的吸附焓变是负值说明吸附是放热的,温度升高不利于吸附的进行。     

耐高温FRK-VES清洁压裂液性能评价

针对国内外清洁压裂液耐温性能较差的问题,开发出一种新型的两性离子表面活性剂压裂液体系。该清洁压裂液体系优化配方为4.0%FRK-VES＋0.30%稀盐酸＋4.0%KCl溶液＋1.0%苯甲酸钠。室内实验对FRK-VES压裂液体系性能进行了评价：耐温耐剪切性良好,120℃的表观黏度为83 mPa.s（170 1/s）,30℃连续剪切60 min的黏度为3167 mPa.s;携砂性能良好,摩阻较小,在常温下与原油和地层水混合可迅速破胶,破胶液黏度小于5 mPa.s,并且无残渣,破胶液界面张力为0.75 mN/m,表面张力为24.8 mN/m;该体系滤失系数为1.93×10-4m/min1/2,对渗透率为1μm2和0.2μm2储层的渗透率伤害率分别为19.56%、25.36%,适合不超过120℃的高温低渗砂岩的储层改造。该清洁压裂液在胜利油田、华北分公司现场施工,效果较好。图3表5参11     

复合固体推进剂松弛模量的获取方法

采用传统方法、Joonas方法以及基于Prony级数的数据拟合法分别研究了HTPB复合固体推进剂的松弛模量,并以Prony级数形式表示.利用线黏弹性理论,得到哑铃型试件应力松弛实验和等速率拉伸实验的应力响应理论值,并与实验结果进行对比.结果表明,传统方法由于忽视了应变加载阶段,弹性模量小于实验值,Joonas方法需要计...     

Steady shear and viscoelastic properties of a micro‐crosslinked acrylamide‐based terpolymer

A water‐soluble micro‐crosslinked associating polymer (PASA‐PL): poly (acrylamide/butyl styrene/sodium 2‐acrylamido‐2‐methylpropane sulphonate) (PASA)–phenolic aldehyde (PL) was prepared to reduce the critical associated concentration and enhance the thickening properties for the linear PASA polymer in aqueous and brine solutions. The consecutive steady shear and viscoelastic properties were investigated to explore the correlations between the rheologic performance and supramolecular structures for the PASA‐PL brine solutions. Upon consecutive steady shear, the intermolecular hydrophobic association is greatly reinforced because of the expansion of the coiled PASA‐PL chains at the suitable shear rate, and the brine solution exhibits obvious shear thickening behavior. The steady shear results show that the intermolecular hydrophobic association is reversible, and that the polymer chains do not degrade upon shearing. The PASA‐PL brine solutions with 50 g L⁻¹ NaCl have predominantly elastic character over the angular frequency range at the polymer concentration higher than 1.0 g L⁻¹, which is remarkably strengthened with a slight increase in polymer concentration. The PASA‐PL brine solutions display a salt‐thickening effect and predominantly exhibit elastic character over the angular frequency range at 10–50 g L⁻¹ NaCl. These results demonstrate that the viscoelastic behavior of the PASA‐PL solutions mainly depends on the formation of hydrophobically associated structures via the intermolecular association strengthened by the micro‐crosslink of PASA with PL. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

新型连续混配型清洁压裂液体系研究

通过对粘弹性表面活性剂分子结构的分析,筛选出了低温下溶解性能好、易成胶的长链烷基季铵盐表面活性剂VES-1、VES-2,并通过与激活剂(水杨酸钠)、聚合醇等进行配方优化组合,确定了YCQJ-2清洁压裂液稠化剂的配方,同时评价了1.0%～5.0%YCQJ-2清洁压裂液的性能。结果显示,YCQJ-2清洁压裂液稠化剂与清水按照一定比例混合,即可形成粘弹性较好的冻胶,破胶容易,表/界面张力低,对岩心的伤害率低于15.0%,而且可以实现就地连续混配、连续施工,简化了施工程序,节约成本,保护环境。     

阻尼加强筋板架减振性能试验研究

基于试验模态分析,考察船用加强筋板架模型在不同敷设位置,全部进行约束阻尼等处理方式对系统动态特性的影响。试验结果表明:(1)板架表面进行约束阻尼处理后,在不同测点位置,结构表面振动均有不同程度的衰减;(2)阻尼减振作用与激励源传播距离有关,在激励点位置,阻尼减振效果不佳;(3)阻尼减振效果与激励方式、阻尼敷设位置均有一定关系,局部阻尼处理在特定情况下可达到与全部阻尼处理相当的减振效果。     

Rheological behaviour of concentrated mandarin juice at low temperatures

Several rheological properties of concentrated mandarin juice were investigated, quantifying thixotropic behaviour and fitting experimental data to the Hahn, Weltman, and Figoni–Shoemaker equations. The latter one proved best for modelling the time dependency response. Pseudoplastic behaviour fitted well with the Herschel–Bulkley model in the interval between ?12 and 6 °C, in which yield stress and the flow behaviour index scarcely changed with temperature. The consistency coefficient and apparent viscosity both decreased as temperature increased. Fitting these consistency data to the Arrhenius‐type equation, a value of 33 kJ mol^?1 for activation energy was obtained. Concentrated mandarin juice displayed viscoelastic properties in the temperature range between ?12 and 6 °C, with the elastic character (determined by the juice’s pectin content) predominating over the viscous nature at low frequency values, but with this behaviour being inverted for high values. Furthermore, as the temperature became higher, the elastic character became more important than the viscous nature.     

Viscoelastic properties of branched polyacrylate melts

The viscoelastic properties of poly(n‐butyl acrylate), poly(ethyl acrylate) and poly(methyl acrylate) melts have been studied using samples that varied in both molar mass and the mol% branched repeat units, these properties having been previously determined by gel permeation chromatography and ¹³C NMR spectroscopy, respectively. Poly(n‐butyl acrylate) was studied most extensively using seven samples; one sample of poly(n‐butyl acrylate), two samples of poly(ethyl acrylate) and one sample of poly(methyl acrylate) were used to study the effect of side‐group size. Storage and loss moduli were measured over a range of frequency (1 × 10^?3 to 1 × 10² rad s^?1) at temperatures from T_g + 20 °C to T_g + 155 °C and then shifted to form master curves at T_g + 74 °C through use of standard superposition procedures. The plateau regions were not distinct due to the broad molar mass distributions of the polyacrylates. Hence, the upper and lower limits of shear storage modulus from the nominal ‘plateau’ region of the curves for the seven poly(n‐butyl acrylate) samples were used to calculate the chain molar mass between entanglements, M_e, which gave the range 13.0 kg mol^?1 < M_e < 65.0 kg mol^?1. The Graessley–Edwards dimensionless interaction density and dimensionless contour length concentration were calculated for poly(n‐butyl acrylate) using the mean value of plateau modulus (1.2 × 10⁵ Pa) and three different methods for estimation of the Kuhn length; the data fitted closely to the Graessley–Edwards universal plot. The Williams–Landel–Ferry C₁ and C₂ parameters were determined for each of the polyacrylates; the data for the poly(n‐butyl acrylate) samples indicate an overall reduction in C₁ and C₂ as the degree of branching increases. Although the values of C₁ and C₂ were different for poly(n‐butyl acrylate), poly(ethyl acrylate) and poly(methyl acrylate), there is no trend for variation with structure. Thus the viscoelastic properties of the polyacrylate melts are similar to those for other polymer melts and, for the samples investigated, the effect of molar mass appears to dominate the effect of branching. © 2001 Society of Chemical Industry