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1 Dnyanasadhana College, Thane.
hhh Department of Chemistry T.Y.B.Sc. Analytical Chemistry Paper-IV Sem-VI Thermogravimetric analysis Dr.Bhagure G.R.

2 TGA – Principle of Operation
Thermogravimetry (TG) determines the mass change of a sample as a function of temperature or time. A good tool for: Quality Control And Assurance Failure Analysis Of Complex Polymer Mixtures And Blends. Study of a variety of chemical processes accompanied by mass changes.

3 Thermal Methods of Analysis
Properties are measured as a function of temperature, time, or both Heat flow – direction and magnitude Mass change – loss / gain Mechanical properties Sheer Strain Dynamic loading Gas evolution CHM 342

4 INSTRUMENTATION: The instrument used in Thermogravimetric (TG) is called a thermobalance. It consists of several basic components in order to provide the flexibility necessary for the production of useful analytical data in the form of TGA Curve as shown in Fig.1. Basic components of a typical thermobalance are listed below; i) Balance ii) Furnace: heating device iii) Unit for temperature measurement and control (Programmer) iv) Recorder: automatic recording unit for the mass and temperature changes These components may be represented by simple block diagram as in Fig.2

5 INSTRUMENTATION Thermo balance Furnace: heating device Sample Holder
Recording Balance and Balance Control Furnace: heating device Furnace temperature Programmer Sample Holder Atmospheric Control Recorder: automatic recording unit for the mass and temperature changes

6 Characteristic of good Thermobalance
Weight change of sample should be recorded continuously. Furnace should reach maximum desired temperature. Heating rate should be linear and reproducible Sample holder should be in hot zone Provision to vary the heating rate in furnace Balance mechanism should be protected from furnace and corrosive gases. Recording of tem and wt to an accuracy of 0.01g. Balance should be sensitive

7 Factors affecting on Thermobalance Instrumental factors
Sample Characteristics

8 Sample holder Geometry
Instrumental factors Heating rate Furnanace atmosphere Static Air Dynamic Air Inert Atmosphere Sample holder Geometry

9 Sample Characteristics
Weight of sample Large amount sample Small amount Sample Particle size of sample Smaller or greater particle size Compactness of sample Loose or compressed sample

10 Application of Thermogravimetry

11 Copper sulphate pentahydrate
Percentage Wt. Loss B Temperature

12 Decomposition of Copper sulphate pentahydrate
Reaction Temperature CuS04.5H20 CuS04.H H20 K CuS04.H20 CuS04 +H20 K CuS Cu0+ S02+1/2 02 K 2Cu  + Cu20+ ½ 02

13 Thermogravimetric Analysis (TGA)
A technique that permits the continuous weighing of a sample as a function of temperature and/or as a function of time at a desired temperature

14 Applications To measure a property of interest, such as specific heat, latent heat or heat of reaction To fingerprint a particular material or substance To assess high temperature stability of materials To detect phase transformations Fundamental studies of reaction kinetics

15 TGA Applications: Inorganic

16 TGA Applications: Organics
Identification of polymers and pharmaceutical agents Thermal stability of synthetic and natural polymers and other organics Analysis of polymer-matrix composites Kinetics and mechanism of solid organics – gas reactions Residual solvent determinations

17 TGA Applications: Organics
Determination of purity and thermal stability of Primary and secondary standards used in titrimetry. Determination of correct drying temperature of substance. Determination of composition of complex mixtures. Thermal decomposition of inorganic and Inorganic polymeric substances. Solid state reactions Roasting and calcining of minerals . Identification of polymers and pharmaceutical agents Thermal stability of synthetic and natural polymers and other organics Analysis of polymer-matrix composites Kinetics and mechanism of solid organics – gas reactions Residual solvent determinations

18 THANK YOU


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