热分析技术在橡胶领域应用得越来越广泛，本文简要介绍了示差扫描量热仪DSC、热重分析仪TGA、动态力学分析仪DMA和热机械分析仪TMA的基本原理和在橡胶领域的应用实例。

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。

Modulated DSC (MDSC) can be easily understood by comparing it to its well-established precursor, differential scanning calorimetry (DSC). Conventional DSC is an analytical technique in which the difference in heat flow between a sample and an inert reference is measured as a function of time and temperature as both the sample and reference are subjected to a controlled environment of time, temperature, atmosphere and pressure. The schematic of a typical “heat flux” DSC cell is shown in Figure 1. In this design, a metallic disk (made of constantan alloy) is the primary means of heat transfer to and from the sample and reference. The sample, contained in a metal pan, and the reference (an empty pan) sit on raised platforms formed in the constantan disk. As heat is transferred through the disk, the differential heat flow to the sample and reference is measured by area thermocouples formed by the junction of the constantan disk and chromel wafers which cover the underside of the platforms. Chromel and alumel wires attached to the chromel wafers form thermocouples which directly measure sample temperature. Purge gas is admitted to the sample chamber through an orifice in the heating block wall midway between the raised platforms. The gas is preheated by circulation through the block before entering the sample chamber. The result is a uniform, stable thermal environment which assures excellent baseline flatness and exceptional sensitivity (signal-to-noise). In conventional DSC, the temperature regime seen by the sample and reference is linear heating or cooling at rates from as fast as 200°C/minute to rates as slow as 0°C/minute (isothermal).

A controlled stress rheometer with normal force measurement capability was used to screen a series of liquid pressure sensitive adhesives. The samples were processed in a roll coating application with a pattern bar producing controlled bands of the final coating. Some samples coated well, but others produced surface irregularities such as ribbing or beading and were considered to have failed. Conventional viscometry could not predict which samples were likely to perform well and which were likely to fail. The use of rheometry proved more successful and by calculating certain dimensionless groups, the samples could be ranked in order of suitability. Surface tension information proved to be less relevant than overall viscoelastic data as provided by measurement of normal stress in the fluid under steady simple shear.

DMA-动态力学分析仪是对粘弹性材料表征的全能工具，可以对高分子材料的玻璃化温度，微观结构，宏观力学，蠕变和应力松弛进行测试。这篇文章可以很快地帮助您对DMA技术有初步的了解，以便进一步地对高分子材料进行深入研究。