The document discusses different thermal analysis techniques. It describes the principles, instrumentation, and applications of differential thermal analysis (DTA) and differential scanning calorimetry (DSC). DTA involves measuring the temperature difference between a sample and reference material as they are heated. DSC measures the heat flow into or out of a sample during heating or cooling. Both techniques can identify phase transitions, crystallization events, and chemical reactions in materials.

1. Presented by: Shubham Sharma
Pharmaceutical Chemistry
Roll no. : 20029
Presented to : Dr. Renu Chadha
Professor ,UIPS, Panjab University
Email : shubham00sharma70@gmail.com
6/3/2021

2. CONTENTS
 INTRODUCTION
 TYPES OF DIFFERENT THERMALANALYSIS
 DTA
 PRINCIPLE
 INSTRUMENTATION
 APPLICATION
 DSC
 PRINCIPLE
 INSTRUMENTATION
 APPLICATION
 FACTOR AFFECTING TO THERMALANALYSIS
 REFERENCES
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3. INTRODUCTION
 THERMALANALYSIS
Techniques in which a physical (thermal) property of a
substance is measured as a function of temperature while
the substance is subjected to a controlled temperature
variation.
THERMAL ANALYSIS means the analysis of a change in
a property of a sample, which is related to an imposed
temperature alteration.
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4.  There is difference between “thermo analytical techniques” and “thermoanalytical
methods”.
 The techniques are characterized by the suffix “-metry”, while the more comprehensive
methods, which include the evaluation and interpretation of the measured property
values, are indicated by adding “analysis”.
 Measurements are usually continuous and the heating rate is often, but not
necessarily, linear with time.
 The results of such measurements are thermal analysis curves and the features of these
curves (peaks, discontinuities, changes of slope, etc.) are related to thermal events in the
sample.
When matter is heated, it undergoes
 Physical Changes:- Phase change such as melting Vaporization, crystallization,
transition between crystal structures, change in microstructures in metal alloy &
polymers,
 Chemical Changes:- Include reaction to form new products, oxidation,
decomposition, corrosion.
Continued….
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5. TYPES OF DIFFERENT THERMAL ANALYSIS
Properties Techniques Methods Abbreviations
Mass Thermogravimetry Thermogravimetric
Analysis
TGA
Pressure Thermomanometry Thermomanometric
Analysis
TMA
Electric Properties Thermoelectrometry ThermoelectricAnalysis TEA
Optical Properties Thermooptometry Thermooptometric
Analysis
TOA
Dimensions or
Mechanical
Properties
Thermomechanometry Thermomechanical
Analysis
TMA
Temperature Thermometry Heating & Cooling Curve
Analysis
--
Temperature
Difference
Differential Thermometry Differential Thermal
Analysis
DTA
Heat flow
Difference
Differential Scanning
Calorimetry
-- DSC
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6. DIFFERENTIAL THERMAL ANALYSIS
 Principle:-
 Differential thermal analysis (DTA) is a technique in which the
difference in temperature between a substance and a reference
material is measured as a function of temperature while the
substance and reference material are subjected to a controlled
temperature program.
 The differential temperature is plotted against temperature or time is
called DTAcurve.
 Both sample & reference material heated in controlled condition.
 If any reaction (physical or Chemical changes ) takes place
temperature difference (∆T) will occur between sample & reference
material.
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7. REFERENCE MATERIAL
 The reference material should have the following
characteristics:
 It should undergo no thermal events over the operating
temperature range.
 It should not react with the sample holder or thermocouple.
 Both the thermal conductivity and the heat capacity of the
reference should be similar to those of the sample.
 For inorganic samples- Alumina, and carborundum,
SiC,
 For organic compounds- octyl phthalate and silicone oil.
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8. INSTRUMENTATION
1. Furnace
2. Sample Holder
3. Temperature
measurement
4. Computer-Data
acquisition ,
processing &
control system
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9. FURNACE
 Both sample & reference material match thermally & arranged systematically with
the furnace, so that both are heated or cooled in identical manner.
 The metal block surrounding the well act as heat sink.
 Temperature of the heat sink slowly increases by using internal heater.
 Its temperature range from ambient temperature to l600°C
SAMPLE HOLDERS
 Sample holder called crucible are made up of metallic (Aluminum , Platinum) & ceramic
(silica).
 Sample are usually 1- 10 mg for analysis.
 The dimension of two crucibles & cell well are as nearly identical as possible.
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10. TEMPERATURE MEASUREMENT
 Pair of thermocouples used in DTA.
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11. DTACURVE
1. The initial decrease in T is due to the glass transition. The
glass transition temperature Tg is the characteristic
temperature at which glassy amorphous polymers become
flexible or rubber like.
2. The two maxima are the result of exothermic processes in
which heat is evolved from the sample, thus causing its
temperature torise.
3. When heated to a characteristic temperature, many
amorphous polymers begin to crystallize as microcrystals,
giving off heat in the process. Crystal formation is
responsible for the first exothermic peak.
4. The minimum labeled "melting" is the result ofan
endothermic process in which heat is absorbed by the
analyte.
5. The second peak in the figure is endothermic and involves
melting of the microcrystals formed in thc initial
exothermic process. The third peak is exothermic and is
encountered only if the heating is performed in the
presence of air or oxygen.
6. The final negative change in ∆T results from the
endothermic decomposition of the polymer to produce a
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12. APPLICATIONS
 DTA is a widely used tool for studying and characterizing polymers. The types of
physical and chemical changes in polymeric materials that can be studied by
DTA.
 DTA is also used in the ceramics and metalsindustry.
 DTA is used to study decomposition temperatures, phase transitions, melting and
crystallization points, and thermal stability.
 An important use of DTA is for the generation of phase diagrams and the study of
phase transitions.
 The DTA method also provides a simple and accurate way of determining the
melting, boiling, and decomposition pointsof organic compounds.
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13. DIFFERENTIAL SCANNING CALORIMETRY
Principle:-
 Differential Scanning Calorimetry (DSC) is a Thermal Analysis technique in
which the heat flow rate (power) to the sample is monitored against time or
temperature while the temperature of the sample, in a specified atmosphere,
is programmed.
 It is measure heat into or out of sample.
 Differences in heat flow occur with the occurrence of
two major events-
 The heat capacity of the sample which increases with temperature.
 Transitions occur
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14. INSTRUMENTATION
1. Furnace
2. Sample Holder
3. Temperature
measurement
4. Computer-Data
acquisition ,
processing &
control system
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15. INSTRUMENTATION
 Types of DSC
1) Power-compensated DSC
2) Heat-flux DSC
3) Modulated DSC
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16. 1. POWER-COMPENSATED DSC
 In power-compensated DSC, the temperatures of the sample and
reference are kept equal to each other while both temperatures are
increased or decreased linearly. The power needed to maintain the
sample temperature equal to the reference temperature is
measured.
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17. 2. HEAT-FLUX DSC
 In heat-flux DSC, the difference in heat flow into the sample and
reference is measured while the sample temperature is changed at a
constant rate. Both sample and reference are heated by a single
heating unit.
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18. 3. MODULATED DSC
 Modulated DSC (MDSC) uses the same heating and cell arrangement as the heat-
flux DSC method. In MDSC, a sinusoidal function is superimposed on the overall
temperature program to produce a micro heating and cooling cycle as the overall
temperature is steadily increased or decreased.
Differential Scanning Calorimetry – Principle of Operation
 A sample is placed inside a crucible which is then placed inside the furnace of the DSC
system along with a reference pan which is normally empty (inert gas may be used).
 By applying a controlled temperature program (isothermal, heating or cooling at constant
rates), phase changes can be characterized and/or the specific heat of a material can be
determined.
 Heat flow quantities are calculated based on calibrated heat flow characteristics of the cell.
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19.  According to the thermal transformation, an endothermic or exothermic effect is recorded. In
the case of an endothermic effect, it is needed to provide heat to the system for its
transformation(sample absorbs energy). This will result in a decrease of the temperature in the
system during the transformation(sample releases energy).
In the case of an exothermic effect, the system provides heat during its transformation. This
results in an increase of the temperature in the system.
ENDOTHERMIC AND EXOTHERMIC EFFECTS
- common endothermic effects:
- melting, sublimation
- first order and second order phase transitions
- evaporation, dehydration
- denaturation (protein)
- gelatinization (starch with water)
- common exothermic effects
- Crystallization, Gelation (gel formation)
- Oxidation, combustion, Decomposition, ignition, explosion
- Fermentation, Most of the chemical reactions, Polymerization, reticulation
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20. DSC CURVE
Analysis of a polymer shows several features
due to physical and chemical changes,
including:
 DSC of polymer
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21. APPLICATIONS
 Glass Transition Temperatures :-
Determination of the glass transition temperature T, is one of the most important
applications of DSC. The physical properties of a polymer undergo dramatic changes
at Tg, where the material goes from a glassy to a rubbery state. At the glass transition,
the polymer undergoes changes in volume and expansion, heat flow and heat capacity.
The change in heat capacity is readily measured by DSC.
 Crystallinity and Crystallization Rate:-
In most cases DSC is one of the easiest methods for determining levels of crystallinity.
 Reaction Kinetics:- Many chemical reactions, such as polymer formation reactions,
are exothermic and readily monitored by DSC methods. Melting points – crystalline
materials.
 Desolvation :- adsorbed and bound solvents
 Purity determination :- contamination
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22. FACTOR AFFECTING TO THERMAL ANALYSIS
 Instrumental
1) Furnace Heating rate-↑es heating rate , ↑es decomposition
2) Furnace atmosphere- pure intert gas like N2
 Sample characteristics
1) Sample particle size
2) Weight of sample
 Polymorphic transitions :- Polymorphs and pseudo polymorphs
 Processing conditions :- environmental factors
 Compatibility :- interactions between components
 Decomposition kinetics :- chemical and thermal stability
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23. REFERENCES
1.Douglas A. Skoog, Principles of Instrumental
Analysis, 6th Edition, 894-904.
2.Michael E. Brown ,Introduction to Thermal Analysis
Techniques and Applications, 2nd Edition.
3.Gurdeep Chatwal , Instrumental methods of chemical
analysis : Analytical Chemistry.
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