Thermogravimetric analyzer method and working principle

Thermogravimetric analyzer method and working principle

The thermogravimetric analyzer (Thermo Gravimetric Analyzer) is an instrument that uses the thermogravimetric method to detect the temperature-mass change relationship of a substance. The thermogravimetric method is to measure the relationship between the mass of a substance and the temperature (or time) under program temperature control.

Thermogravimetric analyzer method:

When the measured substance sublimates, vaporizes, decomposes into gas or loses crystal water during the heating process, the quality of the measured substance will change. At this time, the thermogravimetric curve is not a straight line but a decline. By analyzing the thermogravimetric curve, we can know the degree of change of the measured substance, and according to the weight loss, we can calculate how much substance is lost, (such as the crystal water in CuSO4·5H2O, from the thermogravimetric curve we can know The five crystal waters in CuSO4·5H2O are removed in three steps) TGA experiment is helpful to study the changes of crystal properties, such as melting, evaporation, sublimation and adsorption and other physical phenomena of substances; it also helps to study the dehydration of substances , Dissociation, oxidation, reduction and other chemical phenomena. Thermogravimetric analysis can generally be divided into two categories: dynamic (heating) and static (constant temperature). The curve obtained by the thermogravimetric method is called the thermogravimetric curve (TG curve). The TG curve uses mass as the ordinate, and from top to bottom to indicate the mass decrease; temperature (or time) as the abscissa, and from left to right indicates the temperature ( Or time) increase.

working principle

The thermogravimetric analyzer is mainly composed of balance, furnace, program temperature control system, recording system and other parts.

There are two most commonly used measurement principles, namely displacement method and zero method. The so-called displacement method is based on the proportional relationship between the inclination of the balance beam and the mass change, the inclination is detected by a differential transformer, etc., and it is automatically recorded. The zero method uses the differential transformer method and the optical method to measure the tilt of the balance beam, and then adjusts the current of the coil installed in the balance system and the magnetic field, so that the coil rotates to restore the tilt of the balance beam, the so-called zero method. Since the force applied by the coil rotation is proportional to the mass change, and this force is proportional to the current in the coil, it is only necessary to measure and record the current change to obtain the mass change curve.

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