Differential Thermal Analysis (DTA) Tests

Differential scanning calorimetry is a thermoanalytical technique in which the difference in the amount of heat required to increase the temperature of a sample and reference is measured as a function of temperature. This technique measures the energy transferred to or from a sample that undergoes a physical or chemical change.

For example, with this method, it reveals information about the deterioration of the analyzed wood, the interaction between wood components and the change in their chemical structure upon heat treatment. Different differential thermal analysis (DTA) curves occur depending on the type of wood. The curves obtained are used as a distinguishing feature.

Differential thermal analysis (DTA) is a technique in which the temperature difference between the sample and the reference material is monitored against time or temperature while programming the temperature of the sample in a particular atmosphere. During these analyzes, the sample and reference are placed symmetrically in the furnace, then the furnace is controlled under a temperature program and the temperature of the sample and the reference is changed. During this process, a differential thermocouple is installed to detect the temperature difference between the sample and the reference. The device called thermocouple allows measurement between minus 200 degrees and plus 2320 degrees. The sample temperature is determined with this device. Substances that do not change in the measuring temperature range are used as a reference.

When the furnace starts heating, the reference and sample begin to warm with a slight delay depending on their respective heat capacities. The differential thermal analysis signal changes after heating starts until a static state is reached, and after stability is achieved, it reaches an amount compatible with the difference in heat capacity between the sample and the reference. The signal in the static state is known as the fundamental. From here, the reaction temperature is determined.

As can be seen, with the differential thermal analysis technique, any temperature difference between the sample and the reference is recorded and involves heating or cooling a test sample and an inert reference under the same conditions. This different temperature is then plotted versus time or temperature, and the difference in heat flow between the reference and the sample kept in the same environments (i.e. in the differential thermal analysis furnace) is calculated. In this way, changes in the sample that lead to heat absorption or development are detected relative to the inert reference.

The first important applications of the differential thermal analysis (DTA) method were the study of phase diagrams and transition temperatures, and the qualitative analysis of metals, oxides, salts, ceramics, glasses, minerals and soils. For many problems, it is advantageous to use both the differential thermal analysis (DTA) method and the thermogravimetric analysis (TGA) method.

Thermal analysis is the analysis of a change in a property of a sample related to an imposed change in temperature. The sample is usually in a solid state and changes in heating include melting, phase transition, sublimation, and separation.

Analysis of the change in mass of a sample during heating is known as thermogravimetric analysis. In this analysis, mass changes in a material under a controlled atmosphere are measured as a function of temperature (or time). Its main use is to measure the thermal stability and composition of a material. This analysis is most useful for dehydration, decomposition, desorption and oxidation processes.

Differential thermal analysis (DTA) is the most widely used thermal analysis method. During differential thermal analysis, the temperature of a sample is compared with the temperature of an inert reference material during a programmed temperature change. The temperature is kept the same until thermal events such as melting, decomposition or change in the crystalline structure occur. When an endothermic event occurs in the sample, the temperature of the sample lags behind the reference and a minimum is observed on the curve. However, if, on the contrary, an exothermic event occurs in the sample, the temperature of the sample exceeds the temperature of the reference and a maximum is observed on the curve. The area under the endotherm or auxotherm is related to the energy of the thermal event.

In solving many problems, it is advantageous to use both the differential thermal analysis and the thermogravimetric analysis (TGA) method, since the differential thermal analysis events can then be grouped into those with or without mass change. Both methods are used to determine the following conditions: melting points, glass transition temperatures, crystallinity, moisture and volatile content, thermal and oxidative stability, purity and conversion temperatures.

Our organization provides differential thermal analysis (DTA) testing services to demanding enterprises within the framework of national and international standards, with a trained and expert staff and advanced technological equipment, among numerous testing, measurement, analysis and evaluation studies.