TA仪器Discovery 流变仪

传统的旋转流变仪是在理想流动条件（黏度流动）下工作的，使用板、椎板或同心圆筒表征复杂材料，尤其在线性黏弹区域更好。但往往复杂流体在这种条件下最难测量的。测试或滑动过程中采样工具界面上的沉降有明显的效果，且能够减少仪器的操作范围。 Traditional rotational rheometry has been dealing with ideal flow conditions (viscometric flows) using plate, cone-plate or concentric cylinder geometries to characterize complex materials, preferably in the linear viscoelastic region. Complex fluids, however are often difficult to measure under these conditions. Sedimentation during testing or slippage at the sample-tool interface have a significant effect on the results and reduce the operation range of the instruments. ?Furthermore do viscoelastic flows by no means represent the real flow situation in batch or continuous reactors and processing machines during mixing and/or incorporation of additives, etc. For example, in order to simulate and to understand the gelatinization of starch, a mixing element is used as the standard geometry to avoid settling of the non soluble starch particles since the early days of rheological testing.

由导电性颗粒和非导电液体混合而成的电流变液的微观结构状态在有无外电场作用差异巨大，从而表现出显著不同的流变特性。这类体系有着广泛应用前景，对电流变液流变特性的系统表征有十分重要的意义和实用价值，TA仪器最新研制的电流变附件是研究这类流变的理想工具。

分析流变学是确定材料微观结构从而测量粘弹性响应的学科。分析流变学是分析化学在相同意义上与其他作为其他分析方法基础上的流变性能测试的延伸。固有粘度分析技术是一种分析流变学。分析流变学可适用于任何材料系统的流变响应，这种响应很大程度上取决于微观结构分析。?

流变光学是指将光学技术应用于变形系统的结构、取向和压力测量。光学测量可以是对流变力学测试的一个重要的补充，因为他们可以帮助理解表现在聚合物和胶体材料上的机制控制的流动性能。光学分析模块OAMII采用偏振测定或测量光的偏振，以确定在主体流动和变形材料的折射率的各向异性。与流变仪相反，光学方法不需要接触材料，且可以专注于极小体积的材料的测试。

Rheological testing of thermoplastic materials can be performed on both solid samples and on melts. This is important because the choice of material form and physical state is more than a matter of convenience: Product performance issues usually are related to solid samples properties; process ability issues can be correlated with polymer melt properties. In either case, since rheology is an indirect and non-unique measurement of structure, the application of rheology to solving processing and product performance problems often reduces to comparative analysis of good and poor performing samples.

Injection molding big parts and complex shapes with rigid PVC is probably the most demanding PVC process in terms of melt viscosities. PVC is a material with physical and chemical characteristics that make it process slightly more difficult in comparison with other thermoplastics. The high viscosity contributes to the development of a high amount of heat when the material is subjected to the shear applied by the screw during the plasticization. The thermal instability of the compound results from the breakdown either when it is heated at temperatures higher than admissible or when it remains for too long at high temperature. Hence evaluating the material behavior in terms of its thermal stability and melt viscosity is important for end-users of PVC compounds. This paper attempts to assist engineers who are faced with the task of screening compounds from various suppliers, prior to full-scale evaluation of the compound in production machines.

对于给定的测量夹具系统，旋转流变仪的最低扭矩实际限制了其能所量测的最小应力，又由于量测的应力总是等于样品黏度与施加剪切速率的乘积，因此，对于低黏度样品来说，测试时允许施加的最小剪切速率不可避免地会受到所用测试夹具系统所能量测的最小应力限制。换句话说，对于黏度比较低的样品，流动测试中所允许设置的最小剪切速率并不是仪器所能达的速率最小值，而是与被测样品的黏度存在关联关系。实际测量中可以设定的最小剪切可由测量系统所能量测的最小应力除以黏度估算。

应变：Strain，物体在受到外力作用下会产生一定的变形，变形的程度称应变，γ； 应变速率：Strain Rage，应变对时间的变化率，单位为秒的倒数；

小振幅振荡剪切及数据处理，小振幅振荡剪切及数据处理，小振幅振荡剪切及数据处理 小振幅振荡剪切及数据处理

一个医药公司想比较两种洗液的扩散速度，以确定不同配方的作用效果。可是两种洗液的量非常少，难以用合适的方法进行表征。