In my research group we used DSC in an attempt to determine the degree of crystallinity of LDPE. Attached please find an example of a thermogram obtained. In order to determine the degree of crystallinity we need to know the heat of fusion which is the area under the 2nd endothermic peak. However, the left-hand side of the peak has an ill-defined end-point compared to the right-hand side which makes it very challenging to assign a baseline. I decided to use a horizontal baseline. Any advice?
Dear Dr Robert Thomas Bachmann,
When I had been studying my M.Sc. I faced the problem(MACRO. MOL. ENG., 2016). It is caused by crystaline portion of chain of LDPE which are imperfect. The best way is to choose a 2nd derivative baseline and afterward the lowest limit point of must be adjusted so that the line be along with the curve in higher temperature. It means your lower limit must be moved to lower temperature.
Sincerely
Hi Dr. Robert,
I've faced the same type of problems sometimes for complexes. My suggestion to overcome this :(i) repeat the DSC run for the same sample discs, (ii) lower the heating rate (5 K/min), (iii) try to isolate the sample with highest purity.
Hi Robert,
I agree with Mohammed that lowering your heating rate may help. You might also try reducing the mass of your samples, if feasible.
Best,
Sam
- Badges
- Science method
- Similar topics
- Methodology
- Crystallography
- X-ray Diffraction