2004 Training Seminars DSC

1. 5 2004 Training SeminarsDSC MDSC® What it’s all about & how to get better results

2. What Does MDSC® Measure? • MDSC separates the Total heat flow of DSC into two parts based on the heat flow that does and does not respond to a changing heating rate • MDSC applies a changing heating rate on top of a linear heating rate in order measure the heat flow that responds to the changing heating rate • In general, only heat capacity and melting respond to the changing heating rate. • The Reversing and Nonreversing signals of MDSC should never be interpreted as the measurement of reversible and nonreversible properties

3. Modulated DSC® Theory • MDSC® uses two simultaneous heating rates • Average Heating Rate • This gives Total Heat Flow data which is equivalent to standard DSC @ same average heating rate • Modulated Heating Rate • Purpose is to obtain heat capacity information at the same time as heat flow

4. Average & Modulated Temperature (Heat-Iso) Modulated Temperature Average Temperature

5. Average & Modulated Temperature (Heat-Iso) Modulated Temperature Amplitude Average Temperature

6. Average & Modulated Heating Rate Period

7. MDSC® Raw Signals

8. Modulated DSC® Theory • MDSC® Heat Flow & Signals Total = Reversing + Nonreversing

9. Modulated DSC® Theory • MDSC® Data Signals Total = Reversing + Nonreversing • Heat Capacity • Glass Transition • Most Melting Reversing Transitions

10. Modulated DSC® Theory • MDSC® Data Signals Total = Reversing + Nonreversing • Enthalpic Recovery • Evaporation • Crystallization • Thermoset Cure • Protein Denaturation • Starch Gelatinization • Decomposition • Some Melting Nonreversing Transitions

11. MDSC® of Quench-Cooled PET

12. When & Why to Run MDSC® • Always run a standard DSC @ 10°C/min first • If you’re looking for a glass transition -- • If the glass transition is detectable and can be routinely analyzed, then you don’t need to use MDSC • However, if the Tg is hard to detect, or has an enthalpic recovery, then run MDSC

13. When & Why to Run MDSC® • If looking at melting and crystallization – • If the melting process looks normal (single endothermic peak) and there is no apparent crystallization of the sample as it is heated, then there is no need to use MDSC • However, if melt is not straightforward, or it is difficult to determine if crystallization is occurring as the sample is heated, use MDSC

14. When & Why to Run MDSC® • If you want heat capacity (Cp) – run MDSC • To get Cp by normal DSC (Q1000 is an exception due to Direct Cp) • Use High heating rates, >10°C/min • Three experiments required • Baseline • Reference (sapphire) • Sample

15. The Natural Limitations of DSC • The next several slides discuss some of the natural limitations of DSC & how they are solved by MDSC®. This is by no means a complete list, just some of the more significant limitations.

16. The Natural Limitations of DSC • It is not possible to optimize both sensitivity and resolution in a single DSC experiment. • Sensitivity is increased by increasing weight or heating rate • Although increased sample size or heating rate improves sensitivity, they decrease resolution by causing a larger temperature gradient within the sample • MDSC® solves this problem because it has two heating rates: the average heating rate can be slow to improve resolution, while the modulated heating rate can be high to improve sensitivity

17. Sensitivity & Resolution PC-PEE Blend 16.13mg MDSC® .424/40/1

18. Natural Limitations of DSC (cont.) • Baseline curvature and drift limit the sensitivity of DSC for detecting weak transitions • MDSC® eliminates baseline curvature and drift in the Heat Capacity and Reversing signals by using the ratio of two measured signals rather than the absolute heat flow signal as measured by DSC.

19. Where’s the Tg? Tablet Binder, 44%RH 3.08mg MDSC® 1/60/5 Vented pan

20. Here’s the Tg!

21. Natural Limitations of DSC (cont.) • Transitions are often difficult to interpret because DSC can only measure the Sum of Heat Flow within the Calorimeter • MDSC® minimizes this problem by providing not only the Total Heat Flow signal but also the heat capacity and kinetic components of it

22. Complicated Example Quenched Xenoy 14.79mg 10°C/min

23. MDSC® Aids Interpretation Xenoy 13.44 mg MDSC .318602

24. Natural Limitations of DSC (cont.) 4. It is often difficult to accurately measure the crystallinity of polymers by DSC because the crystallinity increases as the sample is being heated in the DSC cell. • To measure the correct crystallinity requires the ability to: • determine the true heat capacity (no transitions) baseline • quantitatively measure how much crystallinity developed during the heating process

25. DSC of Amorphous PET/PC Mixture…Where is the PC Tg ?

26. MDSC® Shows Two Tgs in Polymer Mixture MDSC® .318/40/3

27. MDSC® Gives Correct Crystallinity of Zero

28. Optimization of MDSC® Conditions • Proper selection of the three experimental parameters is important in order to maximize the quality of the results. • In general, temperature is controlled to either provide or not provide cooling during the temperature modulation • Cooling is desirable for heat capacity transitions • Cooling is undesirable for melting & crystallization

29. Select Modulated Mode

30. Select signals to store

31. Select Test (Template)

32. MDSC® Heat-Cool Modulation Heating & Cooling Heating Rate goes below 0°C/min

33. MDSC® Heat-Iso Modulation No Cooling Heating Rate never goes below 0°C/min

34. MDSC® Heat-Iso Amplitudes No Cooling Period (sec) H e a t i n g R a t e This table is additive, i.e. the heat only amplitude for a period of 40 sec & a heating rate of 2.5°C/min is the sum of the values for 2.0°C/min & 0.5°C/min Amplitude (40s,2.5°C/min)=0.212+0.053=0.265°C

35. MDSC® Conditions for Q Series DSC Glass Transitions (Tg) • For “standard Tg”: Sample Size: 10 – 15 mg Amplitude*: 2X Table Period: 40 seconds Heating Rate: 3°C/min • If Tg is Hard to Detect Sample Size: 10 – 20 mg Amplitude*: 4X TablePeriod: 60 seconds Heating Rate: 2°C/min • If Tg has Large Enthalpic Relaxation Sample Size: 5 – 10 mg Amplitude*: 1.5X TablePeriod: 40 seconds Heating Rate: 1°C/min *Use a minimum of 0.5°C amplitude

36. MDSC® Conditions for Q Series DSC Heat Capacity (Cp) • Heating Rate; isothermal up to 5ºC/min • Modulation Period • 100 seconds with crimped pans • 120 seconds with hermetic pans • Modulation Amplitude; 1.5X Table Value with a minimum of 0.5ºC • Sample Size; 10-15mg

37. MDSC® Conditions for Q Series DSC Melting and crystallinity: • Sample Size; 10-15mg • Period • 40 sec. with crimped pans • 60 sec. With hermetic pans • Heating Rate • Slow enough to get a minimum of 4-5 cycles at half-height of the melting peaks • Amplitude • Use “Heat-Iso” amplitude which provides no cooling during temperature modulation (see Table)