Presentation is loading. Please wait.

Presentation is loading. Please wait.

MODULATED DSC . WHAT IS MDSC  ? l In MDSC®, a sinusoidal heating profile is overlaid on the standard linear ramp l From this experiment, the standard.

Similar presentations


Presentation on theme: "MODULATED DSC . WHAT IS MDSC  ? l In MDSC®, a sinusoidal heating profile is overlaid on the standard linear ramp l From this experiment, the standard."— Presentation transcript:

1 MODULATED DSC 

2 WHAT IS MDSC  ? l In MDSC®, a sinusoidal heating profile is overlaid on the standard linear ramp l From this experiment, the standard Heat Flow curve is separated into two components called the Reversing Heat Flow and the Non- Reversing Heat Flow l Total Heat Flow is the same as in standard DSC l Reversing Heat Flow is the Cp component l 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  l Results obtained using current MDSC® practice are strongly dependent on modulation period  Long periods are required  Low heating rates necessary l Tzero™ MDSC® greatly reduces period dependence  Shorter periods may be used  Higher heating rates are possible

8 FAST MDSC 

9

10

11

12 Lactose

13 HEAT CAPACITY SIGNAL

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

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

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

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

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

19 Tzero  MDSC  HEAT CAPACITY CALIBRATION

20

21 HEAT CAPACITY UNITS ON ALL SIGNALS


Download ppt "MODULATED DSC . WHAT IS MDSC  ? l In MDSC®, a sinusoidal heating profile is overlaid on the standard linear ramp l From this experiment, the standard."

Similar presentations


Ads by Google