Differential Scanning Calorimetry (DSC)

The principle underlying differential scanning calorimetry (DSC) is that enthalpy changes in a material (the amount of energy absorbed or released by a substance during a chemical reaction or physical change) can be detected and measured. These enthalpy changes can be used to characterize the material.

If a thermal effect occurs in the sample as it is heated or cooled, the temperature will deviate from the reference temperature, which follows the programmed temperature. By measuring the difference in enthalpy changes between a sample and a reference, DSC provides valuable information on the physical and chemical properties of the sample.

For example, as a sample undergoes a phase change, it either absorbs or releases energy. This could be an exothermic effect such as crystallization, where the sample releases energy and becomes hotter than the reference. This energy is detected by the DSC instrument. By measuring the difference between the heat flow of the sample with the heat flow of the reference, you can determine the enthalpy change associated with the phase transition of the sample.

DSC results are plotted as a heat flow curve in mW as a function of temperature or time. DSC can be used to determine many thermal properties of materials by analyzing the shape of the heat flow curve.

Watch our video to discover the benefits of METTLER TOLEDO's differential scanning calorimeters.

METTLER TOLEDO offers two DSC measurement modes: heat flux and power compensation.

Heat flux DSC: During the controlled temperature program, a thermal effect in the sample will cause its temperature to deviate from the reference temperature. For example, an exothermic effect such as crystallization releases energy, and the sample becomes hotter than the reference. In heat flux DSC, the temperature difference between the sample and the reference is measured. To create a DSC measurement curve, heat flow is calculated from the measured different in temperature. All our DSC instruments can measure in heat flux mode.

Power compensation DSC: In power compensation mode, the energy used to keep the temperature difference between the sample and reference as close to zero as possible is measured.  In METTLER TOLEDO’s DSC 5+, this is achieved by two local heaters on the sensor, one below the sample crucible and one below the reference crucible. During an exothermic effect such as crystallization, the sample becomes hotter than the reference. The heater on the reference side will then activate, increasing the reference temperature until it matches the sample temperature.

An endothermic effect in the sample, such as melting, absorbs energy and the sample becomes cooler than the reference. The sample heater will then activate, increasing the sample temperature until it reaches the reference temperature.

The amount of power introduced by the sensor heaters is very precisely measured. This results in a heat flow signal with outstanding resolution, and excellent separation of close-lying effects.

METTLER TOLEDO’s fast scanning calorimeter, the Flash DSC also uses power compensation.

In addition to heat flux and power compensation DSC, there are many types of differential scanning calorimetry, each with its own advantages and limitations. The choice of DSC technique depends on the specific sample being studied and the application.

METTLER TOLEDO is a leading provider of differential scanning calorimeters (DSC). We offer a diverse portfolio of DSC instruments, each designed with unique features and capabilities to cater to various applications. Explore our product brochures now to find the perfect DSC solution that suits your needs.

High-pressure differential scanning calorimetry (HPDSC) allows the thermal behavior of materials to be studied in a high-pressure environment by introducing a pressurized gas to generate the required conditions. The advantages of HPDSC include shorter analysis times due to accelerated reactions, and the simulation of pressurized process conditions.

Fast scanning calorimetry DSC (Flash DSC)

Fast scanning calorimetry or Flash Differential Scanning Calorimetry (Flash DSC) is used to study the thermal behavior of materials at very high heating and cooling rates. In Flash DSC, the sample is exposed to heating rates of up to 3,000,000 K/min and cooling rates of up to 2,400,000 K/min, allowing the study of materials that exhibit extremely fast thermal reactions and the analysis of reorganization processes that are not possible using conventional DSC.

DSC-Microscopy allows a sample to be examined visually while it is heated or cooled. This technique is useful when DSC curves exhibit effects that cannot immediately be understood or that generate little or no enthalpy. This enables, for example, identification of solid-solid transitions, overlapping effects, and the shrinkage of the sample to be observed.

DSC-Photocolorimetry (UV-DSC)  enables photo-induced curing reactions to be studied as well as the effects of exposure time and UV light intensity on material properties to be investigated.

Differential scanning calorimetry (DSC) works by measuring the amount of energy absorbed or released by a sample (the heat flow) as it is subjected to a controlled heating or cooling cycle, or held isothermally at the same temperature. As the temperature changes, or with time held at a certain temperature, the sample undergoes thermal transitions, such as melting, crystallization, glass transition, phase changes, or chemical reactions, during which, heat energy is either absorbed or released.

Using a special type of sensor, differential scanning calorimetry detects the energy absorbed or released by the sample during these transitions or events. The difference in heat flow between a sample and a reference crucible is plotted in mW as a function of temperature or time to create a DSC measurement curve. The enthalpy changes associated with the thermal events appear as endothermic or exothermic peaks on the curve.

Evaluating and interpreting the shape of the heat flow curve allows us to determine the thermal characteristics and behavior of a material. Thermal analysis software is used to control the instrument, and present and evaluate the shape of the measurement curve.

Differential scanning calorimetry (DSC) is widely used for investigating the thermal properties of different materials such as polymers, composites, chemicals, petrochemicals, metals, ceramics, pharmaceuticals, oils, and foods. This thermal analysis technique provides valuable information about the thermal characteristics and behavior of the sample and is commonly used for researching new materials, failure analysis, safety studies, and quality control.

Common applications of differential scanning calorimetry include:

• Thermal stability (oxidation induction time, decomposition temperature)
• Curing and chemical reactions
• Kinetics (for curing, shelf-life, stability)
• Polymorphism
• Purity determination and impurities
• Specific heat capacity
• Identification (based on characteristic melting onset temperature or glass transition temperature)

DSC is commonly used in the following industries:

• Pharmaceuticals: Characterizing drug compounds, analyzing purity, and developing stable drug formulations.
• Polymer Science: Studying thermal transitions such as glass transition, crystallization, and melting, helps optimize processing and understand material properties.
• Food Science: Investigating the behavior of fats, starches, and other food components during processing and storage, to determine product quality and shelf life.
• Materials Science: Analyzing phase transitions in various materials, from metals and ceramics to composites and nanomaterials, aids in their development and application.

Discover METTLER TOLEDO’s comprehensive collection of thermal analysis applications, covering a wide range of techniques and analytical topics.

To use a differential scanning calorimeter (DSC) instrument, you first need to prepare a small, precisely measured sample and place it in a sample crucible or pan. A lid can be placed on the crucible if required, depending on the application. A reference crucible of the same type is prepared and typically remains empty. Sample preparation is key and must be performed correctly, which is explained in this How to Prepare DSC Samples video.

The temperature program is set, with start and end temperatures and appropriate heating and cooling rates. The appropriate furnace gas must be selected depending on whether an inert or oxidizing atmosphere is required. Once the DSC furnace has reached the start temperature, the sample and reference crucibles are placed into the furnace. This can be done manually or automatically with a sample robot. At the temperature program progresses, the DSC instrument detects the difference in heat flow between the sample and reference crucibles. The results are plotted on a measurement curve that represents the enthalpy changes of the sample with respect to temperature or time.

For more detailed information on how to use METTLER TOLEDO’s DSC instruments, download the manual.

DSC (differential scanning calorimetry) and DTA (differential thermal analysis) are two thermal analysis techniques used to study the thermal behavior of materials. Although both techniques involve the measurement of temperature changes in a material, they differ in the way these changes are measured and the type of information they provide.

Differential scanning calorimetry measures the amount of heat flow into or out of a sample as it is subjected to a controlled temperature program, providing information on the exothermic and endothermic processes which occur in the sample as a function of temperature or time. Differential thermal analysis provides information on only the temperature difference between the sample and the reference.

DSC is generally better suited for studying phase transitions and thermal properties of materials, such as melting points, glass transitions, and enthalpy changes. It provides more information about the thermal behavior of a material and is often used to characterize polymers, pharmaceuticals, and other organic materials.

DTA can be used to study thermal stability and oxidation behavior, such as the melting points and thermal stability of inorganic materials.

METTLER TOLEDO's differential scanning calorimeters (DSC) are not directly designed for performing differential thermal analysis (DTA). Because DSC provides more information about the phase transitions, thermal properties and behavior of materials, the DSC technique is generally recommended.

When choosing a DSC machine, there are several key parameters that you should consider, including:

• Temperature range: The temperature range of the DSC machine should be appropriate for your application. For example, if you analyze materials that are to be used in high-temperature environments, you will need a DSC instrument that can heat the sample to the usage temperature.
• Heating and cooling rate: These should be appropriate for your sample and application. Some DSC machines offer faster heating and cooling rates than others, which can benefit some applications.
• Resolution: A high-resolution instrument enables a clearer separation of overlapping thermal events. This can occur when multiple transitions or reactions take place within a narrow temperature range, making it difficult to distinguish between the individual events. Polymers can often exhibit overlapping thermal transitions, such as glass transitions, melting points, and crystallization.
• Sensitivity: The sensitivity of the instrument determines how weak a thermal event it can detect. If you analyze samples with weak thermal effects, you will need a DSC instrument with high sensitivity.
• Sample capacity: The sample robot capacity of the DSC machine should be appropriate for your workflows. For example, the sample robot for the DSC 5+ handles up to 96 samples and 7 reference crucibles.
• Atmosphere control: Some DSC machines may offer the ability to control the furnace atmosphere during analysis, which can be useful for analyzing materials under specific conditions such as a controlled humidity, or in the presence of a particular gas or even a vacuum.
• Software and data analysis: The DSC machine's software and data analysis capabilities should provide the necessary tools for analyzing your data. The STAR^e™ software from METTLER TOLEDO provides nearly limitless evaluation possibilities, offering modularity, flexibility, and measurement automation. This software also helps regulated industries to remain compliant. All of our thermal analysis systems are controlled from one powerful software platform.
• Budget: The price of the DSC machine is an important consideration, as it should fit within your budget while still providing the necessary features and capabilities for your application.

Considering these key parameters, you can choose a DSC machine suitable for your application and analytical needs. Contact our experts today at METTLER TOLEDO to explore our DSC solutions and find the perfect instrument for your needs.

The gas inside a DSC furnace plays a crucial role in the experiment. An inert atmosphere such as nitrogen, argon, or helium prevents oxidation by shielding the sample from oxygen. This ensures that the results obtained are accurate and based solely on the sample behavior. Alternatively, an oxidative atmosphere such as air or oxygen may be required, for example, in experiments to determine oxidation induction time (OIT).

Another effect is that the thermal conductivity of the gas affects the speed at which heat reaches the sample and sensor. For example, high-conductivity gases, such as helium, may provide slightly different measurement results compared to others. Therefore, selecting the appropriate gas is essential to prevent any unwanted reactions and to ensure accurate results.

In addition to the furnace gas, by using an inert gas in the crucible chamber (which holds the samples until the measurement begins), samples are protected before the experiment starts. This not only prevents changes to the sample material, but also ensures the weight of the sample remains the same until the analysis begins.

In power compensation mode, the temperature difference between the sample and reference is kept as close to zero as possible. In METTLER TOLEDO’s DSC 5+, this is achieved in a single furnace by two local heaters located on the sensor, one below the sample and one below the reference. For example, during the standard heating program, an exothermic effect such as crystallization releases energy, and the sample becomes hotter than the reference, which follows the programmed temperature. The heater on the reference side will then activate, increasing the reference temperature until it matches the sample temperature.

An endothermic effect in the sample, such as melting, absorbs energy and the sample becomes cooler than the reference. The sample heater will then activate, increasing the sample temperature until it matches the reference temperature.

The amount of power introduced by the sensor heaters is very precisely measured and used to plot the DSC measurement curve. This results in a heat flow signal with outstanding resolution, and excellent separation of close-lying effects.

METTLER TOLEDO's DSC 5+ thermal analysis system features the MMS 1 MultiStar™ sensor, which allows you to select power compensation or heat flux mode depending on your application. It contains 136 thermocouples to offer exceptional sensitivity and resolution, allowing the separation of close-lying thermal effects.

Yes! METTLER TOLEDO differential scanning calorimeters can be seamlessly integrated with a number of accessories, such as a sample robot. The innovative DSC 5+ sample robot includes a gas-purged sample chamber to protect samples from the environment and operates automatically without manual intervention.

The sample robot can handle up to 96 samples and 7 reference crucibles and will automatically dispose of the crucibles after the measurement has finished. With the unique lid-handling system, the sample robot is able to pierce the lid of hermetically-sealed aluminum crucibles, or remove the protective lid of unsealed crucibles, just before the measurement starts. This means your sam­ples are protected and the sample mass does not change before the experiment starts.

Many other options and accessories can also be integrated with METTLER TOLEDO differential scanning calorimeters, including the DSC Microscopy kit, DSC photocalorimetry kit, and various high-sensitivity MultiSTAR® DSC Ceramic Sensors, to maximize performance.

Additionally, our DSC instruments can be integrated with our STARe software to enhance your thermal analysis with unparalleled evaluation capabilities. The software's modular design, intuitive flexibility, and automation features simplify your workflow, ensuring comprehensive compliance within regulated industries.

The thermal analysis software used for differential scanning calorimetry allows users to easily set up and run experiments. This includes defining heating/cooling rates, temperature ranges, and data acquisition parameters. The software must accurately record and display the raw DSC data (heat flow vs. temperature). It should also provide essential analysis tools such as peak integration, baseline correction, and the calculation of common thermodynamic parameters.

Moreover, users should have the ability to generate clear and well-organized reports that summarize the experimental data, analysis results, and interpretations.

METTLER TOLEDO offers the thermal analysis STAR^e software, which is the most complete and comprehensive thermal analysis software on the market, providing unrivalled flexibility and unlimited evaluation possibilities.

Differential scanning calorimetry (DSC) has some limitations that need to be kept in mind.

For example, limited resolution can make it difficult to distinguish between overlapping thermal effects, such as multiple endothermic or exothermic peaks. In this case, the temperature-modulated DSC method can be used, or even a TMA (thermomechanical analyzer) or DMA (dynamic mechanical analyzer) instrument.

Another potential limitation is that DSC requires a relatively small sample size (usually a few milligrams), which may not be representative of the bulk material. Small samples can lead to a low signal-to-noise ratio, while large samples may not fit in the crucibles.

DSC results can be influenced by the sample's morphology, surface area, or particle size distribution. Hence, the sample should be homogeneous, as any impurities or variations in the sample may affect the results. Careful sample preparation is necessary.

Some experiments may require extremely high heating and cooling rates that are not possible using conventional DSC. In this case, fast scanning calorimetry may be appropriate for materials that exhibit very fast thermal events or reactions and to study reorganization processes that are not possible using conventional DSC.

While DSC is a valuable technique for thermal analysis, it is important to consider these limitations.