Thermal analysis and their application

thermal analysis and their application it all

1. S.N.PATEL INSTITUTE OF TECHNOLOGY AND RESEARCH CENTRE,UMRAKH Thermal analysis (DTA) and their application Subject : P& IC(2140501) Guided by:

2. C ontents Thermal analysis Classification of thermal analysis Differential thermal analysis(DTA) Principle Instrumentation Advantage and Disadvantage Application

3. Thermal analysis is defined as technique for measuring the difference in temperature between a substance and a reference material (inert substance) with respect to temperature and time. substance is heated it undergoes physical and chemical changes occur. physical change: melting or boiling ,weight loss, gas evolution. chemical change : decomposition or reaction take place. WHAT IS THERMAL ANALYSIS ?

4. Sr no Technique Parameter measured Instrument used Graph 1 Thermogravimetry mass thermobalance Mass vs. temp or time 2 Derivative Thermogravimetry dm/ dt thermobalance dm/ dt vs. temp. 3 Differential thermal analysis Delta T DTA apparatus Delta T vs. temp. 4 Differential scanning calorimetry dH.dt calorimeter dh/ dt vs. temp. 5 Thermometric titrimetry temperature calorimeter Temp vs. titrant volume

5. 6 Dynamic Reflectance spectroscopy Reflectance Spectrophotometer % reflectance and temp 7 Evolved gas detection Thermal conductivity Thermal conductivity cell T.C vs. temp. 8 Thermo mechanical analysis Volume or length dilatometer Volume or length vs. temp. 9 Electrical conductivity Current or resistance electrometer I or R vs. temp. 10 Emanation thermal analysis Radioactivity ETA apparatus E vs. temp.

6. TG/DTA Simultaneous Measuring Instrument Simultaneous TG/DTA improves ease of operation, sensitivity and analytical accuracy

7. P rinciple : The principle of (DTA) analysis is that sample and reference (inert substance) materials is heating o r cooling at desirable rate simultaneously and they under go chemical and physical change which is measured by recorder. Differential thermal analysis

8. Instrumental detail T his instrument comprises a sample holder with thermocouple assembly ,furnaces, flow rate control assembly ,amplifier, detector ,recorder and furnace temperature controller as mentioned in fig B riefly sample and references are kept in small crucible called sample holder which it connected with thermocouple each. T his crucible made of refractory materials like silica Pyrex nickel or platinum . depending upon the nature of the of the test involved the thermocouple is direct contact with the sample and reference to avoid contamination and degradation . T he function of thermo couple is to ensure that heating or cooling is equally distributed in the sample and reference

9. T hese holders are kept in furnace in which heating is carried out for continuous and desirable heating or cooling furnace . T emperature Control is attached with furnace with furnace now thermocouple is attached with amplifier detector and recorder which is measures the C hemical and physical on heating or cooling the sample and reference . N ow the sample which is to be analyzed and reference are kept in sample holder and heating or cooling is started at desirable flow rate the chemical and physical change during temperature difference with respect to time is measured and recorded which is represented as thermogram the thermogram of calcium a cetate is illustrated below

10. Microprocessor controlled power source Reference sample Environment Control E quipment Thermocouple 1 Amplifier Thermocouple 2 Amplifier Recorder Ice box Block diagram of DTA instrument

11. SAMPLE HOLDER METALIC : nickel,stainless steel,platinum sharp endothermic peak. NON METALIC : glass,silica,sintered alumina sharp exothermic peak. FURNACE For heating the sample. Material used wire or ribbon wound on refractory tube.

12. TEMPERATURE CONTROLLER SENSOR CONTROL ELEMENT HEATER RECORDER DEFLECTION TYPE: Recording pen is moved directly by the input signal. NULL TYPE: Input signal is compared with a reference or standard signal and difference is amplified.

13. Advantage High resolution and a robust easy to use . disadvantage Less satisfactory with regard to resolution of thermal traces and quantitative data. Unable to measure the energy associated with each event.

14. Application DTA techniques are useful for providing many basic transformations,dehydration,decomposition,oxidation,reduction,heat of reaction, specific heat, thermal diffusivity , etc. Melting point and boiling point of any organic compound are easily determined using this techniques . DTA techniques is widely used for characterization of polymer one of the thermogram of polymer as mentioned .

15. decomposition melting oxidation Glass transition crystallization T emperature  T No oxidation

16. 4. Qualitative analysis of the material when two or more substance or polymer are mixed together then mixture undergoes DTA analysis to give characteristic melting point peak of each substance or polymer 5.DTA technique has been widely used for the quality control of large number of substance like cement, glass, soil, catalyst, textiles, explosives, resins,etc

17. 6.It is also utilized for analyze the thermal stability of large no of inorganic compounds and complexes. 7. It is widely used for purity determination and also evaluation of kinetic parameters of polymer, explosives ,pharmaceuticals oils fat and other organic materials.

18. Thank you