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MODULATED DSC

MODULATED DSC. WHAT IS MDSC  ?. In MDSC®, a sinusoidal heating profile is overlaid on the standard linear ramp From this experiment, the standard Heat Flow curve is separated into two components called the Reversing Heat Flow and the Non-Reversing Heat Flow

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MODULATED DSC

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  1. MODULATED DSC

  2. WHAT IS MDSC? • In MDSC®, a sinusoidal heating profile is overlaid on the standard linear ramp • From this experiment, the standard Heat Flow curve is separated into two components called the Reversing Heat Flow and the Non-Reversing Heat Flow • Total Heat Flow is the same as in standard DSC • Reversing Heat Flow is the Cp component • Non-Reversing Heat Flow is the Kinetic Component

  3. MDSC heating profile

  4. Experimental conditions

  5. Raw data

  6. MDSC EXAMPLE ON PET

  7. Tzero MDSC • Results obtained using current MDSC® practice are strongly dependent on modulation period • Long periods are required • Low heating rates necessary • Tzero™ MDSC® greatly reduces period dependence • Shorter periods may be used • Higher heating rates are possible

  8. FAST MDSC

  9. Lactose

  10. HEAT CAPACITY SIGNAL

  11. WHAT IS HEAT CAPACITY? • Heat capacity is the amount of heat required to raise or lower the temperature of a material. • Specific heat capacity refers to a specific mass and temperature change for the material (J/g°C)

  12. WHY IS HEAT CAPACITY IMPORTANT? • Thermodynamic property of material(vs. heat flow) • Measure of molecular mobility • Provides useful information about physical properties of the material as a function of temperature

  13. BENEFITS OF MEASURING HEAT CAPACITY • Structure-property information • Can compare samples run at different heating rates • Can compare samples during heating and cooling to better identify transitions associated with heat capacity and kinetic processes • Can be used to measure absolute crystallinity of polymers as a function of temperature (Vincent Mathot, 1997 NATAS Conference Proceedings)

  14. MDSC METHOD • MDSC® heat capacity equation applies to heat flow to a single body • DSC heat flow is the difference between sample and reference heat flows • The method does not properly account for phase and amplitude differences between sample and reference heat flows and temperatures

  15. Tzero MDSC METHOD • Tzero™ DSC gives independent sample and reference heat flow • Deconvolute sample and reference heat flow separately • Subtract reference reversing and non-reversing heat flow from sample reversing and non-reversing heat flow • Period dependence is greatly reduced • Cp units available for all signals

  16. Tzero MDSC HEAT CAPACITY CALIBRATION

  17. HEAT CAPACITY UNITS ON ALL SIGNALS

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