SBS/MMT共混物改性沥青的稳定性

采用动态剪切流变仪(DSR)与光学显微镜(OM)从动态力学性能及相形态变化的角度研究了苯乙烯-丁二烯-苯乙烯嵌段共聚物与蒙脱土(SBS/MMT)共混物改性沥青的稳定性,同时通过高温贮存稳定性测试对其稳定性作了进一步分析,并对SBS/MMT共混物改性沥青与SBS单独改性沥青及SBS/MMT直接改性沥青的上述性能分别作了比较分析。结果表明,SBS/MMT共混物改性沥青的稳定性整体上较SBS单独改性沥青及SBS/MMT直接改性沥青均有一定程度的提高。     

旋转流变仪在线研究聚合物结晶行为进展

介绍了利用旋转流变仪在线研究聚合物结晶行为的工作原理,对近几年国内外利用旋转流变仪在线研究聚合物结晶行为的成果进行了综述,最后展望了旋转流变仪在聚合物结晶行为研究中的应用前景。     

一种新的Couette流变仪的精度校核

利用新研制的外筒旋转可调压可视化Couette流变仪,开展了强剪切流的空化试验,发现剪切力矩及瞬态温度对剪切空化的影响非常明显。通过传感器温度阶跃响应试验数据,求得温度传感器在静止液体内受阶跃温度变化时的表面传热系数。采用柱坐标系,基于试验获得的纯剪切力矩和瞬态传热微分方程,由数值计算方法求出不同时刻强剪切Couette流的瞬态温度,理论计算值与试验结果较为吻合,表明新的外筒旋转可调压可视Couette流变仪获得的纯剪切力矩和瞬态温度的准确性,以及间隙的均匀性。利用文献[9]的初步估算方法,也可求出强剪切Couette流的温度变化值。对比分析结果表明,所提方法校核精度高且适用范围广。     

全尾砂膏体料浆的流变特性研究

以某矿全尾砂充填膏体为试验料浆,采用正交设计法设计试验方案,利用R/S+SST型流变仪对全尾砂膏体进行流变测试试验,研究质量浓度、灰砂比和淬尾比（水淬渣/全尾砂）三因素对流变参数的影响规律。试验结果利用极差分析、方差分析和多元回归分析方法分析。结果表明：膏体的屈服应力与浓度呈单调递增函数关系。膏体具有料浆的触变性和剪切变稀等流变特征。在质量百分比浓度、灰砂比和淬尾比3个影响因素中,影响顺序为质量浓度＞淬尾比＞灰砂比;三因素中质量浓度对流变参数的影响比较显著。     

超高温高压流变仪的研制与应用

针对现有仪器无法满足超高温高压流变性测试需求的问题,研制了超高温高压流变仪,该仪器主要由工控机、黏度测量系统、温度控制系统、压力控制系统4个部分组成。在研制工程中,通过一种非接触式黏度测量方法解决了测试腔体密封问题,通过独特的温控算法和介质切换冷却技术实现了大跨度温度范围内的精确温控和高效冷却。该超高温高压流变仪可以在模拟钻井温度、压力、钻头转速的条件下测量样品黏度,最大测试压力为220 MPa,最高测试温度为320℃,最低测试温度为-20℃。使用该超高温高压流变仪对钻井液样品进行了恒压变温以及恒温变压流变性测试,结果证明该仪器可以测量水基和油基钻井液在超高温高压条件下的流变性,可用于深井、超深井钻探用钻井液体系优化。      

水包油钻井液高温高压流变性研究

用7400型高温高压流变仪对“八五”期间研制的华北任平1井低密度水包油乳化钻井液高温高压流变性进行了实验研究。系统地测试了温度、压力对该钻井液流变性的影响;运用宾汉模式、幂律模式、卡森模式和赫-巴模式对该钻井液高温高压流变数据进行了系统拟合分析,得出赫-巴模式是描述该钻井液高温高压流变性的最佳模式,就工程应用而言,二参数的卡森模式也可以用于描述水包油乳化钻井液高温高压流变性。并研究了赫-巴流变方程中各参数随温度和压力的变化规律;还对该钻井液高温高压流变数据进行了回归分析,建立了预测低密度水包油乳化钻井液高温高压流变性能的模式。     

Estimation of the ends pressure drop in an online capillary rheometer—using the neural network approach

Using an online or inline capillary rheometer as a tool of rheology measurement would come into the ends pressure drop problem. In order to derive the actual pressure drop of the capillary, another capillary with the same diameter and different length is needed (according to Bagley correction) but would result in a more complex mechanism. In this study, a neural network approach is proposed to estimate the ends pressure drops in an online capillary rheometer. The back propagation learning algorithm is used for network training. The shear rate, the die pressure, and the ratio of diameters of the reservoir to the capillary are taken as the neural network inputs, and the ends pressure drop is taken as the output. Two hundred of training sets that are made from a laboratory capillary rheometer are used for network training. The trained neural network can be consequently applied to real-time assessment of the ends pressure drops in the online capillary rheometer. It is concluded that using the proposed method for calculating the ends pressure drop is effective. Besides, the simplicity of the mechanism provides good portability for both online polymer characterization and quality control in processing. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2183–2186, 1999     

Advances in layered double hydroxide (LDH)-based elastomer composites

This article reviews the advances in layered double hydroxide (LDH) materials and the synthesis of LDH-based elastomer composites. The potential of tuning the structure of LDH materials for desired properties and applications has attracted both academic and industrial interest in recent years. The modification of LDH materials and the use of such materials in the synthesis of composites with different elastomer matrices have been critically analyzed. Emphasis has been given to the use of Mg-Al LDHs and Zn-Al LDHs with different elastomers. The use of modified LDHs with elastomers substantially improves their mechanical, thermal and optical properties. Even “smart properties” of elastomers, such as reversible thermotropic optical characteristics, have been realized with the use of LDH-based multifunctional additives in rubber formulations. The flame retardance of some elastomer composites has also been enhanced with the use of modified LDHs. The possibility of replacing ZnO with LDH during rubber compounding has also been discussed, which would lead to drastic interventions in the well-established rubber processing technologies. LDH materials have also been reported to be biocompatible. Therefore, among the various possible applications of LDHs in different material development processes, their use in rubber technology offers the potential for environmentally friendly rubber products, even tires. Throughout this article, the structure, synthesis, properties and applications of elastomer/(LDH) composites are discussed, including suitable examples taken from the relevant literature.     

Rheological Analysis of Sucrose Solution at High Temperatures Using a Microwave‐Heated Pressurized Capillary Rheometer

Thermal process design, optimization, and deviation require the knowledge of engineering properties of food, such as rheological behavior, which is highly dependent on temperature. If a process is calculated based on the parameters obtained by extrapolation, it might lead to over‐ or underprocessing. The long time required for the product to reach the desired temperature, which is usual in many rheometers, may induce unexpected changes on the product. Model solutions are often used in engineering projects in order to simulate characteristics of real products. Thus, the objective of this study was to obtain rheological data of sucrose model solution at the actual high UHT (ultra‐high temperature) process temperatures using a pressurized capillary rheometer, heated by a microwave system. The results provide the rheological behavior of the sucrose solutions and show that there is no deviation of the linearity of the Arrhenius plot above 100 °C for this product. This work was useful to illustrate the use of the applied methodology and to validate the newly built microwave‐heated capillary rheometer. The data obtained confirm the stability of nonsaturated sucrose solution when treated above 100 °C and presents an important contribution to the literature database, since sucrose solutions are used as models for many table syrups, such as maple and sorghum syrups.     

THE IMPORTANCE OF SOLVENT COMPOSITION AND ADSORPTION EFFECTS ON THE FLOW PROPERTIES OF

Capillary rheometry data are presented for concentrated solutions of polybutadiene dissolved in mixed volatile solvent systems composed of benzene, butadiene, and butene 1. Unusual flow phenomena, associated with polymer adsorption at capillary tube walls, are observed for polybutadiene in a solvent composed of benzene and butene 1, but not observed at the same polymer concentration in a pure benzene solvent or for a mixed binary solvent where the butene 1 is replaced by butadiene. The unusual flow phenomena include a diameter dependency in the viscosity measurements when end effects are eliminated, and a diameter dependency in the end correction itself. Correction of the diameter dependent viscosity data is successfully made by postulating an effective negative slip velocity (polymer adsorption). The thickness of the polymer adsorbed layer relative to the tube diameter is of the same order as observations for other polymer solutions both in capillary and packed bed flows. It is argued that the flow phenomena observed in the polybutadiene-benzene-butene 1 solutions and not observed in the polybutadiene-benzene-butadiene solutions of identical composition is related to the solvent system itself—benzene and butadiene being a good mixed solvent for polybutadiene relative to benzene and butene 1 in the same ratio. The work was initiated and completed in response to material handling problems encountered in a commercial process for the manufacture of polybutadiene.