Differential Scanning Calorimetry (DSC)
What is it?
Differential Scanning Calorimetry (DSC) is the most commonly used thermal analysis tool. By measuring either the temperature change (delta T) or energy flow (power compensation) in a sample as it passes through transitions, one can detect changes in the material’s heat capacity and enthalpy. We offer both heat flux and power compensated DSC, as each have applications which they excel at. This allows us to provide a wide range of special techniques including controlled cooling, isothermal recrystallization, photo curing, modulated DSC, fast scanning or fast cooling DSC to allow the investigation of more complex problems.
We offer the following methods* with a variety of DSC instruments available:
*Not all possible specific testing methods may be listed here
Conventional DSC (-70 to 725°C)
Isothermal curing and recrystallization
Modulated Temperature DSC
There are a multiple method types that involve a non-linear temperature programs to enhance the resolution of simultaneously occurring transitions. This is also used to determine the heat capacity of the sample. Common techniques are MDSC™, StepScan™, and TOPEM™.
Heat Capacity and Specific Heat are important properties for the understanding and engineering of materials. DSC remains the best way to measure heat capacity and we offer this by both traditional ASTM and modulated methods.
Thermal Conductivity via DSC
Thermal conductivity is measurable to some extent in a DSC, generally within the range of 0.10 to 1.0W/(K•m). This test is performed by a modulated temperature test protocol in a DSC .
Fast Scanning DSC
Fast scanning DSC utilizes a heating rate of 300°C /min to 750°C/min in order to determine particularly weak transitions, or transitions within a highly filled material that may not be viable using a conventional DSC method. This method is also able to resolve overlapping transitions due to the amplified level of detection. We are also able to provide the ability to cool at these rates, which allows studying of the recrystallization behavior of materials. Also known as HyperDSC™
Purity is a serious issue in every industry; an impure batch of material can have degraded durability or fail outright. In a DSC curve, the melting temperature curve becomes broader as the level of impurity increases. However, this method is performs best at a relatively low level of impurity (97%/mol pure or greater). As it is a direct physical method, it is often used to verify standards for GC and LC as well as test APIs.
Crystallinity and Amorphous content
The amount of the crystalline phase in a material
In polymer – strength and clarity are affected degree of crystallinity
In pharmaceuticals, storage life, solubility, etc. are affected by the amount of amorphous material present
Alternative to X ray diffraction
Photo-DSC allows the in depth analysis of a photo-cured reaction as it progresses. Fiber optic cables allow the light from a UV source to be transmitted to the DSC cell. There are several methods that can be used to test a photo-cured system, such as
Monitoring the cure energy
Obtaining the percent of the material that has been converted, as in some cases full conversion to the cured material is not required
Testing the residual or post cure amount
Determining the cure kinetics
In many cases there is some amount of material that remains uncured. This may not be viewable in a standard DSC, but fast scanning DSC methods allow us to track even the smallest amount of uncured material thermally.
This can also be used as a method of quality control between different product lots.
High Pressure DSC
Applying pressure to a sample in the DSC allows several things to occur:
It suppress the volatiles released from the reaction giving a cleaner signal
It raises the boiling point of solvents so that they no longer obscure transitions
It speeds up reactions. This is particularly useful for oxidative induction times (OIT)
Heat-Cool-Heat Experiment on Nylon Blend
Purity by DSC