General Principles of Temperature Modulated DSC

Temperature modulated DSC uses the heat-flux DSC instrument design and configuration to measure the differential heat flow between a sample and an inert reference material as a function of time. However, in TMDSC a sinusoidal temperature modulation is superposed on the linear (constant) heating profile to yield a temperature programme in which the average sample temperature varies continuously in a sinusoidal manner  

The total heat flow at any point in a DSC or TMDSC experiment is given by 

Typical TMDSC heating profile with the following experimental parameters / = 1 K/min, p = 30 s and x = Under these conditions 

TMDSC data are calculated from three measured signals time, modulated heat flow and modulated heating rate (the derivative of modulated temperature). The raw data are visually complex and require deconvolution to obtain standard DSC curves. However, raw data are useful for revealing the sample behaviour during temperature modulation, as well as fine-tuning experimental conditions and detecting artefacts. 

As described in Section 5.5, the sample heat capacity is generally estimated in conventional DSC from the difference in heat flow between the sample and an empty sample vessel, using sapphire as a calibrated reference material. Alternatively, C can be determined from the difference in heat flow 

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