I conducted a DSC test of a polyolefin material, and you can see its normalized heat flow vs. temperature in the attached image (endo down). That is my first time analyzing the DSC curves. is the increasing trend of normalized heat flow vs. Temp usual?
In literature, I used to see a dropping slope (it shows the drop in heat capacity of organic materials by increasing the Temperature). Then by applying the baseline slope, it is easily transformed into a plateau.
but in my raw data, the trend is not decreasing. Do you have any experience resulting in such a curve?
It is not unusual to observe an increasing trend of normalized heat flow with increasing temperature in DSC measurements of some materials. This is particularly common in crystalline materials, where the heat flow corresponds to the heat required to melt the material. The heat required to melt a crystalline material typically increases with increasing temperature, leading to an increasing trend in the DSC curve.
However, it is important to ensure that the observed trend is not an artifact of the DSC measurement, such as improper baseline correction or instrument calibration. It is also possible that the observed trend is due to some other thermal transition or reaction occurring in the sample at higher temperatures, which is leading to an increase in heat flow.
To confirm the origin of the observed trend, it may be helpful to analyze the DSC curve in more detail, such as by examining the derivative of the curve or by performing additional characterization techniques such as X-ray diffraction or microscopy. It may also be useful to compare the results with other DSC measurements of similar materials or with published literature on the topic.
In any case, it is important to carefully analyze and interpret DSC data to ensure that the observed trends are representative of the material being studied and are not due to experimental artifacts or errors.
This could be caused by the presence of impurities or other components in the material that have a higher heat capacity than the polyolefin. Another reason could be the presence of physical or chemical interactions between the polyolefin and other components in the sample or the instrument.
You could try running a blank experiment without any sample to check the baseline and the instrument's performance. You could also try analysing a different sample of the same material to compare the results.
There might be other questions of help to clear that phenonmena you have observed from the DSC traces:
Q1) at the first glance, it looks like an issue from the baseline calibration, if that DSC curves was obtained by other staff, instead of yourself. Then, check with the person who is in charge of that DSC machine.
Q2) if the answer to Q1 is that the baseline has been calibrated well by the protocal, then you might need to run one more time at the same conditions to see if that DSC curves is repeatable or not.
Q3) if that curves is repeatable, something with your sample and more details are on the DSC runnings, like samples are in open pan or sealed one, or sealed one with a punched hole in the lid, which one suits your case that goes to Q4 for further comsideration.
Q4) if samples in an open pan for DSC running, I assume your are using N2 or Argon as generally used in most cases, that suggested there are some impurities or compound in your sample leading to some reactions with themself, or some impurities with your polyolefin.
Other things are just like Febin and Thomas suggested. Hope those could be of some help.
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