Thermal analysis-DSA-TGA

1. DSC & TGA
Differential Scanning Calorimetry and Thermal Gravimetric Analysis
Pashaie.mokhtar7@gmail.com

2. Different Techniques
• Thermometric Titration (TT)
• Heat of mixing
• Thermal Mechanical Analysis (TMA)
• Thermal Expansion Coefficient
• Dynamic Mechanical Analysis (DMA)
• Viscoelastic Properties
• Differential Scanning Calorimetric (DSC)
• Heat flow during Transitions
• Thermal Gravimetric Analysis (TGA)
• Weight Loss due to decomposition
• Derivative Thermogravimetric Analysis (DTG)
• Differential Thermal Analysis (DTA)
• Heat of Transitions
• Temperature Programmed Desorption (TPD)
• Temperature at which gas is desorbed from (catalyst) surface
• Emission gas Thermoanalysis (EGT)

3. Basic Principle
• Sample is heated at a constant heating rate
• Sample’s Property Measured
• Wt TGA
• Size TMA
• Heat Flow DSC
• Temp DTA
• Gas evolved TPD

5. The adsorption of heat will be different in the two pans due to the different composition in the pan. In
order to keep the temperature of the two pans constant during the experiment, the system needs to provide
more or less heat to one of the two pans.

6. What is DSC?
DSC looks at how a material’s heat capacity (Cp) is changed by temperature.
This allows the detection of transitions like melts, glass transitions, phase changes, and curing.

7. Thermal properties of a polymer

8. Heat Capacity
The heat capacity (Cp) of a system is the quantity of heat needed to raise the temperature of the system
of 1 °C. It is usually given in units of Joules/°C. It can be derived introducing two parameters, namely the
heat flow and heating rate.

9. Glass Transition
In the two regimes, before and after the Tg, the polymers have different heat capacities: Usually polymers have a
higher Cp above the Tg. Due to this difference in Cp, the DSC is a valuable method to determine the Tg.
Temperature in the middle of the inclined part of the graph is by definition the Tg.

10. T
V
Tm
Totally crystalline
T
V
Tg
Totally glassy
T
V
TmTg
Semi-crystalline

11. Crystallization
When polymers fall into these crystalline arrangements, they give off heat to the system, thus the process is
exothermic.
1. have confirmation of the occurrence of the crystallization;
2. determine the polymer's crystallization temperature (Tc) as the lowest point of the dip;
3. gain insight into the latent energy of crystallization for the polymer by observing the area
of the dip.

12. Melting
melting is an endothermic transition. The melting is a first order transition since when the melting temperature is
reached; the polymer's temperature does not rise until all the crystals have completely melted.
the latent heat of melting can be measured from the area of the peak

16. Melting of Indium
157.01°C
156.60°C
28.50J/g
Indium
5.7mg
10°C/min
-25
-20
-15
-10
-5
0
HeatFlow(mW)
150 155 160 165
Temperature (°C)Exo Up Universal V4.0B TA Instruments
Peak Temperature
Extrapolated
Onset
Temperature
Heat of
Fusion

17. Glass Transition vs. Melting
Melting occurs only in a crystalline polymer, while the glass transition takes place to just to polymers in the
amorphous state.

18. DSC Instruments
Two types of DSC instrument have been widely used:
The heat flux DSC (e.g., TA DSC and Mettler DSC)
The power compensational DSC (Perkin-Elmer system)

19. Heat flux DSC:

20. Power compensated DSC

21. Modulated DSC
the same heat flux DSC cell is used, but a sinusoidal temperature oscillation (modulation) is overlaid on the conventional linear
temperature ramp, resulting heating rate is sometimes faster than the underlying linear heating rate, and sometimes slower than
the underlying rate

22. Experiment : Thermal behavior of PET
Determine on the PET sample
a. The glass transition, melting and crystallization temperature;
b. The heat of crystrallization and melting.
Preparing sample:
• Cut a piece of PET film from the plastic bottle, clean it with water and dry it.
• Make a thin film with the weight 5-15 mg, (this is the normal sample weight in DSC
experiment).
• Keep the film flat enough and with suitable size for Aluminum pan.

23. Glass transition sensitivity

24. Tg is reversible

44. TGA
Thermal Gravimetric Analysis

45. continuous measurement
of weight on a
sensitive thermobalance
as sample temperature
is increased in airorin an
inert atmosphere.

46. Photodiodes
Infrared LED
Meter movement
Balance arm
Tare pan
Sample platform
Thermocouple
Sample pan
Furnace assembly
Purge gas outlet
Heater
Elevator base
Purge gas inlet
Sample pan holder

47. Quartz Liner
Off-Gases
Balance Purge
Sample
Thermocouple
Sample
Pan
Furnace Core
Purge Gas In

48. Data are recorded as a thermogram of weight versus temperature

49. evaporation of residual moisture or solvent
polymer decomposition
Thermal stability studies
 characterize polymers through loss of a known entity
such as HCl from poly(vinylchloride) Thus weight loss can be correlated with
percent vinylchloride in a copolymer.
 determining volatilities of plasticizers and other additives
Some applications

52. • Heating a sample of Calcium oxalate
• Ca(C204)*xH2O  Ca(C204) *H2O + x-1 H2O
• Ca(C204)*H2O Ca(C204) + H2O
• Ca(C204)  CaCO3 + CO
• CaCO3  CaO + CO2

53. Thermal Degradation of Polyhydroxylated Nylon 6,6
0 100 200 300 400 500 600
-100
-80
-60
-40
-20
0
100
o
C -6.3%
150
o
C -6.9%
200
o
C -19.0%
235
o
C -50.0%
205
o
C
425
o
C
DTG
TG
DTG
WeightLoss(TG),%
Temperature,
o
C
0.0
5.0k
10.0k
15.0k

54. Poly (4-dodecyl-1-4-aza heptamethylene-D-glucaramide)
Thermal decomposition.
0 100 200 300 400 500 600
-100
-80
-60
-40
-20
0
TG(%WeightLoss)
Temperature,
o
C
TGpercent
0
2
-97.5%@400
o
C
-1.3%@150
o
C
188
o
C
0.6%/
o
C
372
o
C
1.3%/
o
C
166
o
C
DTG(%/
o
C)

55. Thermogravimetric analysis of a polymeric blend containing HDPE and
an inorganic filler (phosphogypsum)
0 100 200 300 400 500 600 700 800
-60
-50
-40
-30
-20
-10
0
-62.8%
%weightloss
Temperature,
o
C
TGpercentL

56. Precipitated Zr5O8(SO4)2*15 H2O

57. Analysis of Filtrate from Precipitation
• Precipitation
• 5ZrOCl2 + 2H2SO4+ xH2O  Zr5O8(SO4)2*15 H2O (s) + 10
HCl
• Decomposition
• Zr5O8(SO4)2*15 H2O (s)  Zr5O8(SO4)2*14 H2O (s) + H2O (v)
• Zr5O8(SO4)2  5 ZrO2(s) +2 SO2(v)

58. % Polymer = 64.4%
% Carbon Black = 3.4%
% Glass Fibre = 32.2%