This document provides an overview of differential scanning calorimetry (DSC). DSC is a thermoanalytical technique that measures the heat flow into or out of a sample as it is heated or cooled. It can detect phase transitions like melting or glass transitions. The document discusses the principles, instrumentation, nature of DSC curves, factors affecting curves, and comparisons between DSC and differential thermal analysis.
In DSC the heat flow is measured and plotted against temperature of furnace or time to get a thermo gram. This is the basis of Differential Scanning Calorimetry (DSC).
The deviation observed above the base (zero) line is called exothermic transition and below is called endothermic transition.
DSC ( differential scanning calorimetry) is a thermo-analytical technique for qualitative and quantitative assessment of our analyte on the basis of heat provision and heat withdrawn from pan with compensation of both pans.
In DSC the heat flow is measured and plotted against temperature of furnace or time to get a thermo gram. This is the basis of Differential Scanning Calorimetry (DSC).
The deviation observed above the base (zero) line is called exothermic transition and below is called endothermic transition.
DSC ( differential scanning calorimetry) is a thermo-analytical technique for qualitative and quantitative assessment of our analyte on the basis of heat provision and heat withdrawn from pan with compensation of both pans.
Slide covers three methods of thermal analysis i.e., thermogravimetry, differential thermal analysis, and differential scanning calorimetry. Thermal analysis methods are well-established techniques in research laboratories of pharmaceutical industry. Thermal analysis includes all methods measuring some parameter during the heating of a sample .Thermal analysis is widely used to study the thermal stability, char content, and decomposition temperature of polymer composites reinforced with natural/synthetic fibers/or nanosized fillers etc.
Differential Scanning Calorimetry, or DSC, is a thermal
analysis technique that looks at how a material’s heat
capacity (Cp) is changed by temperature. A sample of
known mass is heated or cooled and the changes in its
heat capacity is tracked as changes in the heat flow.
This allows the detection of transitions like melts, glass
transitions, phase changes, and curing. Because of this
flexibility, DSC is used in many industries including
pharmaceuticals, polymers, food, paper, printing, manufacturing, agriculture, semiconductors, and electronics
as most materials exhibit some sort of transition.
Introduction:
During the past few years, the methods of thermal analysis have been widely accepted in analytical chemistry.
The term thermal analysis incorporates those techniques in which some physical parameter of the system is determined and/or recorded as a function of temperature.
Thermal analysis has been used to determine the physical and chemical properties of polymers, drugs and geological materials.
A calorimeter measures the heat into or out of a sample.
A differential calorimeter measures the heat of sample relative to a reference.
A differential scanning calorimeter does all of the above and heats the sample with a linear temperature ramp (developed by E. S. Watson and M. J. O'Neill in 1962).
DSC is a technique in which the difference in the amount of heat required to increase the temperature of a sample and reference are measured as function of temperature.
Both the sample and reference are maintained at nearly the same temperature throughout the experiment.
Only a few mg of material are required to run the analysis.
DSC is the most often used thermal analysis method, primarily because of its speed, simplicity, and availability.
Principle:
When a sample undergoes a physical transformation such as a phase transition, more or less heat will need to flow to it than to the reference (typically an empty sample pan) to maintain both at the same temp. Whether more of less heat must flow to the sample depends on whether the process is exothermic or endothermic.
For e.g.as a solid sample melts to a liquid it will require more heat flowing to the sample to increase its temp. At the same rate as the reference. This is due to the absorption of heat by the sample as it undergoes the endothermic phase transition from solid to liquid.
Likewise, as the sample undergoes exothermic processes (such as crystallization) less heat is required to raise the sample temp.
By observing the difference in heat flow between the sample and reference, DSC is able to measure the amount of heat absorbs or release during such transition.
Advantages:
It can be used at a very high temperature.
High sensitivity
High resolution obtained
Stability of the material
Flexibility in sample volume/form
Limitations:
It is unsuitable for two-phase mixtures
Does not detect gas generation
Uncertainty of heats of fusion and transition temperatures.
Applications:
Oxidative stability
Crystallinity
Drug analysis
Heat capacity
Purity
Schematic Arrangement of DSC Apparatus
Heat Flux DSC
Power Compensated DSC
Slide covers three methods of thermal analysis i.e., thermogravimetry, differential thermal analysis, and differential scanning calorimetry. Thermal analysis methods are well-established techniques in research laboratories of pharmaceutical industry. Thermal analysis includes all methods measuring some parameter during the heating of a sample .Thermal analysis is widely used to study the thermal stability, char content, and decomposition temperature of polymer composites reinforced with natural/synthetic fibers/or nanosized fillers etc.
Differential Scanning Calorimetry, or DSC, is a thermal
analysis technique that looks at how a material’s heat
capacity (Cp) is changed by temperature. A sample of
known mass is heated or cooled and the changes in its
heat capacity is tracked as changes in the heat flow.
This allows the detection of transitions like melts, glass
transitions, phase changes, and curing. Because of this
flexibility, DSC is used in many industries including
pharmaceuticals, polymers, food, paper, printing, manufacturing, agriculture, semiconductors, and electronics
as most materials exhibit some sort of transition.
Introduction:
During the past few years, the methods of thermal analysis have been widely accepted in analytical chemistry.
The term thermal analysis incorporates those techniques in which some physical parameter of the system is determined and/or recorded as a function of temperature.
Thermal analysis has been used to determine the physical and chemical properties of polymers, drugs and geological materials.
A calorimeter measures the heat into or out of a sample.
A differential calorimeter measures the heat of sample relative to a reference.
A differential scanning calorimeter does all of the above and heats the sample with a linear temperature ramp (developed by E. S. Watson and M. J. O'Neill in 1962).
DSC is a technique in which the difference in the amount of heat required to increase the temperature of a sample and reference are measured as function of temperature.
Both the sample and reference are maintained at nearly the same temperature throughout the experiment.
Only a few mg of material are required to run the analysis.
DSC is the most often used thermal analysis method, primarily because of its speed, simplicity, and availability.
Principle:
When a sample undergoes a physical transformation such as a phase transition, more or less heat will need to flow to it than to the reference (typically an empty sample pan) to maintain both at the same temp. Whether more of less heat must flow to the sample depends on whether the process is exothermic or endothermic.
For e.g.as a solid sample melts to a liquid it will require more heat flowing to the sample to increase its temp. At the same rate as the reference. This is due to the absorption of heat by the sample as it undergoes the endothermic phase transition from solid to liquid.
Likewise, as the sample undergoes exothermic processes (such as crystallization) less heat is required to raise the sample temp.
By observing the difference in heat flow between the sample and reference, DSC is able to measure the amount of heat absorbs or release during such transition.
Advantages:
It can be used at a very high temperature.
High sensitivity
High resolution obtained
Stability of the material
Flexibility in sample volume/form
Limitations:
It is unsuitable for two-phase mixtures
Does not detect gas generation
Uncertainty of heats of fusion and transition temperatures.
Applications:
Oxidative stability
Crystallinity
Drug analysis
Heat capacity
Purity
Schematic Arrangement of DSC Apparatus
Heat Flux DSC
Power Compensated DSC
Differential Scanning Calorimetry (DSC) is one of the important thermal analytical techniques in which specific physical properties of a material are measures as a function of temperature. It is used both in qualitative and quantitative analysis.
DSC is a technique for measuring the energy necessary to establish a nearly zero temperature difference between a substance and an inert reference material as the two specimens are subjected to identical temperature regimens in an environment heated or cooled at a controlled rate.
This technique was developed by E.S.Watson and M.J.O' Neill in 1964.
The device used to measure this is Calorimeter.
There are two types of DSC systems commonly used:
1. Power compensated DSC
2. Heat -flux DSC
A High resolution of PC-DSC is nowadays widely used known as Hyper DSC.
Differential Scanning Calorimetry
this device help you for reverse engineering by using this device you can know about compounds glass transition temp or melting temp.
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diffrential scanning calorimetry is a barnch of analytical chemistryshamilfawasa
DSC can stand for Differential Scanning Calorimetry, a thermal analysis technique that measures how a material's heat capacity changes with temperature
The different type of thermal analysis: principle, instrumentation, advantages, disadvantages, applications, working data, Curve, topology, differences
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2. Introduction
Differential Scanning Calorimetry, or DSC, is a thermoanalytical technique in which
the difference in the amount of heat required to increase the temperature of a
sample and reference is measured as a function of temperature.
The technique was developed by E. S. Watson and M. J. O'Neill in 1962,and
introduced commercially at the 1963 Pittsburgh Conference on Analytical
Chemistry and Applied Spectroscopy.
The first adiabatic differential scanning calorimeter that could be used in
biochemistry was developed by P. L. Privalov and D. R. Monaselidze in 1964 at
Institute of Physics in Tbilisi, Georgia.
3. Principles of DSC
The Sample and Reference are maintained at the same temperature,
even during a thermal event in the sample.
The energy required to maintain zero temperature difference
between the sample and the reference is measured.
During a thermal event in the sample, the system will transfer heat to
or fro from the sample pan to maintain the same temperature in
reference and sample pans.
DSC is a technique in which the difference in the amount of heat
required to heat the temperature of a sample and reference are
measured as function of temperature.
Both the sample and reference are maintained at nearly the same
temperature throughout the experiment.
A Differential Calorimeter measures the heats the sample relative to
a reference.
4. Comparison Of DTA & DSC
1. “DSC” stands for “Differential Scanning
Calorimetry”.
1. “DTA” stands for “Differential Thermal
Analysis.”
2. DSC is a technique in which the difference is
calculated between the amount of heat
needed (heat flow) to increase the
temperature of the sample and the heat
required to increase the temperature of the
reference.
2. DTA is a technique in which the difference is
calculated between the temperatures required
by the reference and the sample when the
heat flow is kept the same for both.
3. DSC is an instrument based on the DSC
technique used to measure heat released or
absorbed during the transition phase.
3. DTA is an instrument based on the DTA
technique.
6. Instrumentation Of DSC
• Two Basic types of DSC Instruments:
Heat Flux DSC
Sample and reference holders:
• Al or Pt pans placed on constantan disc
• Sample and reference holders are
by a low-resistance heat flow path.
Sensors:
• Chromel® (an alloy made of 90% nickel
and 0% chromium)-constantan area thermocouples (differential heat flow)
• Chromel®-alumel (an alloy consisting of approximately 95% nickel, 2% manganese,
2% aluminium and 1% silicon) thermocouples (sample temperature).
Thermocouple is a junction between two different metals that produces
a voltage due to a temperature difference.
7. Furnace:
• One block for both sample and reference cells.
Temperature Controller:
• The temperature difference between the sample and reference is
converted to differential thermal power, which is supplied to the heaters
to maintain the temperature of the sample and reference at the
program value.
Power Compensation DSC:
Sample Holder:
Aluminum or Platinum Pans.
Sensors:
• Platinum resistance thermocouples
• Separate sensors and heaters for
the sample and reference.
8. • Furnace:
Separate blocks for sample and reference cells.
• Temperature controller:
Supply the differential thermal power to the heaters to maintain the
temperature of the sample and reference at the program value.
The main application of DSC is in studying
phase transitions, such as melting, glass transitions, or exothermic
decompositions. These transitions involve energy changes or heat
capacity changes that can be detected by DSC with great sensitivity.
9. Nature of DSC Curves
• The result of a DSC experiment is a curve of heat flux versus temperature or versus
time. There are two different conventions: exothermic reactions in the sample
shown with a positive or negative peak, depending on the kind of technology used
in the experiment.
• This curve can be used to calculate enthalpies of transitions, which is done by
integrating the peak corresponding to a given transition. The enthalpy of transition
can be expressed using equation:
ΔH = KA
• Where ΔH is the enthalpy of transition
• K is the calorimetric constant,
• A is the area under the peak
• The calorimetric constant varies from instrument to instrument, and can be
determined by analyzing a well-characterized material of known enthalpies of
transition.
• Area under the peak is directly proportional to heat absorbed or evolved by the
reaction,
• Height of the peak is directly proportional to rate of the reaction.
10. A schematic DSC curve of amount of energy input (y)
required to maintain each temperature (x), scanned across
a range of temperatures. Bottom: Normalized curves setting
the initial heat capacity as the reference. Buffer-buffer
baseline (dashed) and protein-buffer variance (solid).
11. Factors Affecting Curves
• Two types of factors effect the DSC curve:
1.Instrumental factors:
Furnace heating rate.
Recording or chart speed.
Furnace atmosphere.
Geometry of sample holder/location of sensors.
Sensitivity of the recoding system.
Composition of sample containers.
2. Sample Characteristics:
Amount of sample
Nature of sample
Sample packing
12. Solubility of evolved gases in the sample.
Particle size.
Heat of reaction.
Thermal conductivity.
BLOCK DIAGRAM
13. References & Sources
1. Molecular biology (in Russian). 6. Moscow. 1975. pp. 7–33.
2. Wunderlich, B. (1990). Thermal Analysis. New York: Academic Press.
pp. 137–140.
3. Dean, John A. (1995). The Analytical Chemistry Handbook. New
York: McGraw Hill, Inc. pp. 15.1–15.5
4. B. Wunderlich, Macromolecular Physics, (1980), Vol. 3, Ch. 8, Table
VIII.6.
5. Brydson, J. A., Plastics Materials, Butterworth-Heinemann, 7th Ed
(1999).
6. Ezrin, Meyer, Plastics Failure Guide: Cause and Prevention, Hanser-
SPE (1996).
7. Wright, D. C., Environmental Stress Cracking of Plastics RAPRA
(2001).
