I have a DSC result run from -90oC to 100oC in a heat/cool/heat cycle.
Tg, crystallisation and melting peaks are observed in the heat run. However the cool run, the crystallisation peaks are not reflected. What is the course of this from the polymer?
To answer this question precisely you need to provid a bit more information. What kind of material, settings etc.
First of all, during heating you generally can see the tg, some post cristallisation and melting. The amplitude of the transition signal depends on a lot of parameters, but the most important ones are heating rate and what type of crucible you use. If you want to make something more visible (by increasing the amplitude) you can increase the heating/cooling rate. This will also shift you result to higher (heating) / lower (cooling temperatures).
If you want to analyse the 'properties' and not just the 'thermal history' of your material you anways should make 2 full cycles for analysis. The first heating/cooling sets your material to standard condition. It will give you information abou the thermal history e.g. the production process.
During the second cycle you can observe the material inherent thermal properties (they are also influenced by the heatin/cooling before but its standardized). A broad cristallisation peak (which means you cant really see it during cooling) usually indicates a very diveres morphology (different cristall sizes and irregular cristall nucliation).
If you can't see something after 2x heating and cooling (and increasing the amplitude like described above) you probably don't have cristallisation, but rather some crosslinking or thermal degration. (Depends on your material)
The temp rate is at 2C/min. It is initially equilibrated at -90oC, heated to 100C, cooled to -90oC and then heated to 100C.
Tg, crystallisation, melting peaks occur on the first and second heat run. The cooling run only shows the Tg reverse.
Material is a diblock polymer PEG-PPC.
Is there a special reason why you would use 2K/min instead of the standard 10K/min? I suggest you to use higher heating/cooling rates (10K/min or even 20K/min), a sampel weight of 10mg, N2 atmossphere and an alumnium crucible. This will amplify the heatflux signal at the transition temperatures and shift them a bit (as described above).
If your material is like the one in this paper Article CO2-Based Non-ionic Surfactants: Solvent-Free Synthesis of P...
, you will decrease the nucleus density of your material substatially as you keep the material for quite a long time above Tm. This will reduce the cristallisation peak (the melting peak reversed), especially when cooling with such slow rates. So maybe stop at a lower temperature when heating (comapre with your heating results).- Badges
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