I synthesized paraffin and copper composite nanoparticles to calculate their heat capacity. But I have got no clear peak or any endothermic or exothermic curve in one heating and cooling cycle. Please suggest what this DSC curve means, and what went wrong.
Which type of crucible was used in DSC test? Is you use open crucible, as you have heat losses, you will get a poor results. The effectice parameters in DSC test are initial weght of the sample, gas flow rate, atmospheric gas (please check in your case), heating rate, crucible type (open/close), and so on. Therefore, you should check them precisely.
The type of crucible material used was aluminum (closed lid), there was a weight loss in the sample after the analysis. Also the atmosphere used was nitrogen gas.
Every thing according to me was precise. Could there be a problem with the sample?
So, you can ckeck the calibration of your device by a reference sample and also blank crucible. You should also subtract your test DSC value from the blank crucible value. Have you done this? If the mentioned points are ok, you can then think about material defection. You should also repeat DSC test for three times and compare the results. Hope it woks for you!
I thing you should mention to us what do you expect in heating or cooling this materials?.
Do you expect any phase change like magnetic or structural phase transition.
If there is a phase transition in these materials and does not show any sign on the heating/cooling curves. This can happens if the entropy changes associated with the phase transition is quite small. Try to estimate the expected amount of the associated entropy changes.
Apologies for late reply.
Hossein Dizaji, I have done the calibration with a blank sample. There is no issue with the crucible, instrument, or experiment. I think may be material has some aberration.
Prof. Khalaf, I expect a phase transition from solid to liquid inside the nano shell of the particles. Through this transition, I wanted to see the absorption of energy by the Nanoparticles. But, I can't seem to find any clue with that Dsc curve.
How do you suggest I should measure entropy changes?
The ordinary solid to liquid phase transition is an endothermic process (heat absorption). The associated entropy might be quite small in comparison with magnetic phase transition in magnetic system. I suggest repeating the experiment with doubling the sample quantity Moreover, try to do a TGA/DTA scans for your sample.
Hi,
Coming into this late, but I was looking for info about Paraffin DSC for a project, and came across this.
In my experience this type of behavior occurred when the heating rate was way too high. Using a rate of 5 C/min or less provides much better resolution.
I would guess at this point you've figured it out yourself but I would be interested to know if I am correct.
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