惯性矩对DSR动态测试的影响及其替代方法

以消除动态剪切流变仪（DSR）在动态测试中可能由于仪器惯性影响而失真的现象为目的,通过Arrhenius模型及Cox-Merz关系对DSR测试结果及布氏黏度（BV）测试结果进行替代性研究.结果表明：Arrhenius模型对沥青复数模量拟合效果较好;利用布氏黏度换算的稳态剪切模量来替代复数模量能有效消除沥青在黏弹性测试的高温区段里由于仪器惯性而产生的类似弹性影响的误差,并消除对材料黏弹性响应产生的误解.     

微机数控旋转流变仪的设计

微机数控旋转流变仪是一种泥浆流变参数微机智能检测仪器。介绍了其工作原理、性能指标和特点，以及硬件、传感器设计和软件功能设计。     

基于DSR的沥青胶结料自愈合评价指标分析

为充分认识沥青胶结料自愈合评价指标的适用性,通过动态剪切流变仪(DSR)进行"疲劳-愈合-疲劳"试验,对比分析5种常见沥青胶结料自愈合评价指标(HI_1～HI_5),得到不同自愈合时间、不同损伤程度下70~#基质沥青、SBS改性沥青和橡胶改性沥青的自愈合能力,并讨论了各指标的优缺点及适用性.结果表明:不同自愈合评价指标下,3种沥青胶结料自愈合能力排序不同;HI_1可区分不同条件下沥青胶结料的自愈合程度,自愈合时间较短时更敏感;HI_2仅适用于评价相同损伤程度的沥青胶结料自愈合性能;HI_3可反映自愈合后沥青胶结料疲劳损伤的恢复程度;HI_4不仅受沥青胶结料承受荷载作用能力的影响,还与其初始复数模量的恢复能力有关,不适用于评价沥青胶结料自愈合能力;HI_5同时考虑了沥青胶结料初始复数模量和疲劳损伤的恢复,可反映沥青胶结料综合性能的恢复能力,最适合作为沥青胶结料自愈合性能评价指标.     

聚对苯二甲酸丙二醇酯的热降解性能

采用了旋转流变仪、凝胶色谱等仪器对聚对苯二甲酸丙二醇酯(PTT)的热降解性能进行了研究。研究表明:随着时间的延长,PTT熔体的相对分子质量和熔体黏度明显下降,而相对分子质量分布没有明显变化;随着温度的升高,PTT熔体的降解速度明显增大;在不同剪切速率下,两种国外PTT熔体的热降解速率基本相同;PTT相对分子质量越高,越易发生热降解。     

Modelling creep and recovery response of asphalt binders using generalized burgers model

Abstract

Appropriate modeling creep and response of asphalt binders can save time, and resources and efforts required for multiple experimentations. Creep compliance master-curves were obtained from short duration creep experiments on 10 different asphalt binders each at 0.1 and 3.2?kPa stress levels. It was shown that, a four Kelvin-element generalized Burger’s model could closely approximate creep and recovery response at any combination of loading and unloading cycle. A single run of dynamic shear rheometer used for conducting short time creep experiments at different temperatures, can be adequate for modeling creep and recovery response of asphalt binders.     

A multiple-step slit die rheometer for rheological characterization of extruded starch melts

Extrusion cooking is a very important process in the field of cereal and snack manufacturing. The rheological properties of the starch based matrix strongly influence this process. A newly developed online rheometer was mounted on a twin screw extruder in order to measure these properties. It was possible to obtain viscosity of wheat flour and corn grits at typical extrusion cooking conditions over a shear rate range of three decades. Flow curves for varying screw speed and water content at a constant thermomechanical history of the starch were measured. Also the temperature dependence of the apparent viscosities could be determined showing activation energies in the range found for synthetic polymers. Furthermore, additional pressure drops that occur at step changes of the slit height were detected. Thus, it was possible to evaluate visco-elastic properties of extruded starch melts at different extrusion cooking conditions.     

不定形耐火材料流变性研究新进展

总结了近期不定形耐火材料流变性研究方面的一些新进展,包括新的流变性研究试验方法、流变性的评价方法、浇注料的流变性和流动性之间的关系,以及絮凝剂对浇注料流变性的影响,并提出了今后进行不定形耐火材料流变性研究的建议。     

Melt Rheological and Impact Properties of Thermally Stable PP/mLLDPE Blends

Effect of the heat stabilizer on the melt rheological properties of the blends of polypropylene (PP) with mLLDPE (mettalocene linear low density polyethylene), after thermal degradation in an air oven, was studied. Study carried out is presented to describe the effect of blending ratio and presence of stabilizer on shear stress, shear rate, melt viscosity and melt elasticity parameters. In general, blending of PP with mLLDPE results in an increased viscosity. The viscosity of PP abruptly decreases after the thermal degradation. Interestingly the melt viscosity PP/mLLDPE blend does not show such a marked decrease. This shows that mLLDPE not only acts as an impact modifier but also acts as a thermal stabilizer. The presence of stabilizer in both materials has not shown much difference in melt viscosity thereby suggesting adequate stabilization of the blend system.     

New approach to determine the plastic viscosity of self-compacting concrete

The rheology of concrete is best measured with the use of a rheometer. The slump flow test gives a good indication of the flowability of the mixture and is therefore still used extensively to judge the workability of SCC mixtures. However, this test presents some defects. The objective of this paper is to develop a new methodology for measuring the workability of a SCC.In this article, we have proposed a correlation between the plastic viscosity of concrete, the time and the characteristics of the flow final profile from the V-funnel coupled to a Plexiglas horizontal channel. The proposed approach, verified by experimental results, represents a simple, economical and usable tool on building site, and it allows to characterize rheologically the SCC from its flow.The comparison between our approach and the experimental values of the plastic viscosity shows that, in a laboratory or on site, instead of using a rheometer we can use our approach to characterize the rheological behavior of a SCC.     

使用转矩流变仪评价硬聚氯乙烯的凝胶化度

对硬聚氯乙烯(PVC-U) 转矩流变曲线的分析和实验验证发现, PVC-U的凝胶化度越大,其转矩流变曲线的最小扭矩越高,最大扭矩与最小扭矩的差值越小,据此提出了使用转矩流变仪评价PVC-U凝胶化度的方法。