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。

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。

Modulated thermomechanical analysis is shown to be a useful tool for determining thermodynamic and kinetic, reversing and nonreversing length changes in materials when these thermally induced events take place simultaneously. This ability to separate thermodynamic from kinetic events aids in the interpretation of the thermal curve, measures expansion and contraction taking place at the same time and provides a more accurate estimation of the glass transition temperature than the softening temperature. MTMA may have applications in other measurements where thermodynamic and kinetic length changes occur simultaneously. Such examples may include the softening of organic or inorganic glasses, heat set films and fibers, and shape memory alloys.

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；

流变仪和DMA测试中，都会涉及到一个概念：线性粘弹区，简单来讲，线性粘弹区就是应力与应变呈线性关系，不断增加应变，而模量保持为常数的区域，Linear Viscoelastic Region, LVR。

TMA Q400仪器需要进行的常规校准包括如下几个方面： （1） 力校准（Force Calibration）：用来校准试验过程中通过探针施加到样品上的力，标准过程校准0g，50g和100g三个质量；

为得到精确的测试结果，需定期对TGA进行校准。另外，当如下条件改变时，也需重新校准仪器：吹扫气体，热电偶位置移动，或更换了新炉子。校准主要有以下几个方面：

为得到精确的测试结果，需定期对DSC进行校准。另外，当如下条件改变时，也需重新校准仪器：吹扫气体，冷却附件，或更换了新炉子。根据仪器型号和所选热流，校准主要有以下几个方面：

在DSC测试中，待测样品及参比（如需要）会放置在样品盘中，再将样品盘放到DSC炉内的测试平台上，热通过样品盘由测试平台传递到样品，所以保证优异的热传导性是得到好的测试结果的前提。TA仪器提供了多种样品盘，可以满足不同材料的测试需求，并具有非常好的热传导性。

TA仪器的调制DSC技术，是在传统DSC线性变温程序上叠加一个正弦变化，从而直接测量热流和比热。采用Fourier 转换，热流实时被分解为热容成份和动力学成份。在MDSC®中，DSC的热流称为总热流，热容成份为可逆热流，动力学成份为不可逆热流。总热流信号包含所有的热转化信息，与标准DSC的结果一样。可逆热流中包含玻璃化转变、熔融等信息，不可逆热流中包含动力学的现象，如固化、挥发、熔融和分解等。 *美国专利 Nos. 5,224,775; 5,248,199; 5,346,306 加拿大专利 No. 2,089,225 日本专利No. 2,966,691 MDSC®技术提供： • 将复杂转变分解为更容易理解的成份 • 检测弱转变和熔化时，提高灵敏度 • 在不损失灵敏度的前提下，提高分辨率 • 直接测量热容 • 更准确的结晶度测量

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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).