TA仪器ARES-G2 高级流变仪

对高分子材料常常用熔体流动速率（熔融指数MI）表示材料熔体的流动性，这种测试完全忽略了材料的流动模型，所以对每一个被研究的材料所施加应变历史都不相同。这种单点的数值是粘性和弹性共同贡献的结果。这种完全经验的数值完全没有定义确定的变形，一般而言仅仅作为材料的等级或窗口数值。由于其测量方法的限制，它不可能区分粘性和弹性。很多情况下具有同样MI的材料却表现出截然不同的加工性能。所以熔体流动速率（MI）测试只能用于质量控制，它无法提供材料的基本性能信息或于加工过程相关联。 不过在控制应力/应变流变仪上的动态测试对材料流动行为可以提供非常有价值的信息。流变仪可以通过单一实验准确的测得弹性和粘性响应。 我们研究的样品为三种硬质PVC样品，分别以A，B和C样品来标记。每一种样品PVC样品在稳定剂类型和浓度及基本PVC树脂类型等方面均有明显的不同。

拉伸流变仪的根是是在20世纪初被发现的。Trouton在测试沥青和鞋匠所用蜡时，在这些材料上进行“扭转”和“牵引”变形。通过巧妙的实验他发现，单轴拉伸黏度是剪切黏度的三倍。

ARES DETA（介电配件）是一种扩展ARES应变控制流变仪测试能力的配件，包括材料介电响应的研究。这种能力探测所测材料的导电和电容性能，扩大了ARES流变仪作为表征材料性能的通用仪器的应用范围。

Greases are important lubricating systems that are very interesting to a rheologist since they often exhibit strongly time-dependent behavior [thixotropy], and are able to shear thin by several orders of magnitude in terms of they are to function as lubricants, and keep moving surfaces apart from each other, even at high relative velocities. Traditionally greases are measured in terms of base oil viscosity, pumpability [Lincoln Ventmeter] and via a penetrometer [amongst other tests!]. These test types all provide a single number or data points can be obtained under varying circumstances of say temperature or in that an unworked sample is compared with a worked sample, but too often the results form only a relative measure of the grease.

The challenge for studying fast changing systems with rheology such as UV initiated polymerization and crosslinking is multifold. These materials react within seconds and the moduli change over 2 to 3 decades. UV lights must irradiate the sample homogeneously over a short time period and fast data acquisition. An option for UV curing, using parallel plate has been designed for the ARES rheometer. A fast data sampling device with a new correlator has been developed to provide up to 500 dynamic mechanical data points per second, so the modulus build up can be easily followed. Results are obtained for an acrylate-based pressure sensitive adhesive. The curing reaction is studied as a function of the sample gap, UV intensity and UV exposure time.

Fluid materials, by definition, are systems which flow when subjected to stress. How they respond to an input stress is the heart of rheological testing and may be a complex issue. There are many types of fluids: pure substances, mixtures, dispersions and solutions, falling into the categories of either simple or structured fluids. Each has its own unique behavior when subjected to stress. In general, when a material has a uniform phase, such as a solution or pure substance, it is referred to as a simple fluid. Materials which contain more than one phase, such as solid particles dispersed in a liquid, gas particles in foam or an emulsion of immiscible liquids are considered structured fluids since their rheological behavior is in general dominated by the interactions of the constituents.

负责多组分聚合物是不同类型的聚合物的组合，可以作为单一或多相系统存在。聚合物的成分可根据标准进行划分：成本、加工性能、机械性能、热性能等。合成聚合物的一个最主要原因在于有效控制成本。

Starches are natural products used most extensively as thickening agents in the food industry, but are also widely employed in the adhesives, paper coatings, wood, packaging, and pharmaceutical industries. A fundamental rheological measurement conducted routinely on starches is the evaluation of the gelatinization process. This is accomplished by measuring the viscosity of the starch suspension, while heating and cooling under specific testing conditions. The resultant curve, referred to as the pasting curve, yields important starch performance parameters, including the pasting temperature, peak viscosity, holding strength, and final viscosity.

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。