Differential Scanning Calorimetry
Differential Scanning Calorimetry (DSC) is the measurement of heat flux with respect to a reference as a function of temperature to determine thermal events. Most commonly, an analysis is either performed in an inert nitrogen environment or in an oxidative environment of air. In certain sample types, various pathways or mechanisms that may be present in an oxidative environment are not present in an inert environment.
Examples of thermal events include:
• Melting and freezing
• Vaporization and condensation
• Sublimation
• Passing through a glass transition
• Transitioning between amorphous and crystalline states
• Changing polymorphic forms
• Changing crystalline states of hydration or solvation
Thermal events can require energy or heat to occur and are categorized as being endothermic; e.g. melting, vaporization, sublimation, etc. Other thermal events give off energy or heat when they occur and are categorized as being exothermic; e.g. freezing, condensing, transitioning from an amorphous to a crystalline material, etc. The transition between polymorphic forms may be either exothermic or endothermic. A glass transition, unlike the normal phase transitions, is considered a second-order transition. Thus, the first derivative of the free energy with respect to chemical potential is continuous, but the second derivative is discontinuous. This is believed to be because of the change in thermal expansion and heat capacity of amorphous materials as they transition from their hard, brittle state into a soft, rubber-like state.
DSC is a multipurpose tool. As such, it can be used to generate several types of data that have applicability to nearly any business sector or application. The most common sectors that use DSC include:
• Polymers
• Plastics
• Rubber
• Pharmaceuticals
• Carbons (including carbon black, graphite, graphene, and carbon nanotubes)
• Fire retardants
• Electronics (including solder)
• Proteins and bio-mechanical substances
• Cosmetics
Though most analysis performed on the DSC instrument involve the measurement of melting points or glass transition temperatures, the versatility of the technique lends itself to a broad array of additional analyses. An example would be as determining the effect that various plasticizers and their concentrations can have on the glass transition temperature. Another example would be determining the specific heat capacity, which is the amount of heat required to raise the temperature of a material by 1 degree as detailed in ASTM E 1269 and ISO 11357-4.
Advantages
- Small amount of sample needed
- Can measure small energy changes
- Highly customizable to client specific parameters
- Rapid and accurate
Considerations
- Typical heating rates: 10 or 20 K per minute. Other ramp rates can be requested, though a custom calibration may be required
- A standard DSC analysis consists of 2 heating cycles with a cooling cycle in between
- Typical environment: nitrogen, though oxidative environment can also be requested
- PTL cannot do modulated DSC or microcaloimetry
- The sample and decomposition products should not be corrosive
Sample Requirements
For dry materials, a 20 to 50 mg minimum is requested for the first submission.
For liquid samples, a minimum of 85 µL is requested, though 200 µL is more ideal.
The above sample quantities are preferred. If sample availability is further limited, please contact us to share specifics about your sample and options for suitable sample quantities.
Detection Range
This instrument has been qualified for use from -170 °C to 600 °C.
Data Reported
The glass transition, onset temperature, peak temperature, enthalpy of transition, and selected points of interest are included in the data outputs.
Instrumentation
The DSC instrument used at Particle Technology Labs is the Netzsch DSC 214 Nevio. The instrument has been qualified in compliance with the U.S. Food and Drug Administration’s (FDA) current Good Manufacturing Practices (cGMP) Regulations, 21 CFR Parts 210 and 211 and the United States Pharmacopeia (USP), General Chapters <891> Thermal Analysis and <1058> Analytical Instrument Qualification. When applicable, analyses may be performed per various methods including ASTM D3418, ASTM E2253, ASTM E967, ASTM E968, ASTM E2160, ISO 11357-1, and USP <891>.
