Differential Scanning Calorimetry (DSC)

TA Instruments Q200 Differential Scanning Calorimeter

The TA Instruments Q200 Differential Scanning Calorimeter (DSC) is used to determine the temperature and heat flow associated with material transitions as a function of time and temperature. The instrument can also be used to obtain quantitative and qualitative data on endothermic and exothermic processes of materials during physical transitions that are caused by phase changes, melting, oxidation and other heat related changes. 

Principle

The instrument functions as a heat flux DSC where the sample is encapsulated in a pan along with an empty reference pan which are rested upon a thermoelectric disk surrounded by a furnace. As the temperature of the furnace is changed by supplying heat (typically in a linear rate), the heat is transferred to the sample and the reference pan through the thermoelectric disk. The differential heat flow to the sample and reference is measured by using the thermal equivalent of Ohm’s law.

Strengths

• High accuracy
• Small sample quantity (5 to 15 mg)

Limitations

• This is a destructive technique and the sample is not preserved
• No direct elemental information can be obtained from DSC
• This technique is known to work best for samples that have surface areas that spread relatively flat against the bottom of the pan that is used
• It is not possible to obtain accurate data when a decomposition or reaction event occurs within the same temperature region as the phase transition
• The mass of a given sample has to be maintained constant in order to obtain accurate measurements, therefore, loss of sample due to evaporation or sublimation during the test will lead to errors.

Applications

• DSC can be used to obtain qualitative and quantitative information including glass transitions in amorphous/semi crystalline materials, melting points, boiling points, crystallization time and temperature
• Percent crystallinity can be estimated using a known standard
• Measure heats of fusion and reactions, oxidative stability, rate of cure/ degree of cure, reaction kinetics, specific heat and heat capacity

Technical Specifications

• Heating range: -70 to 400°C
• Heating rates: 1 to 20°C /minute
• Temperature accuracy: ±0.1°C
• Temperature precision: ±0.05°C