As its known that PVDF has 5 crystalline phases. Is the relative crystallinity of all the phases same or different. Is there some study published on it yet?
or this is just an absurd question from my end.
Kindly help.
Dear Akanksha Adaval ,
For sure, there is a possibility to have different crystallinity's over the obtained phases.
Calculating the crystallinity is not a straight forward procedure. Even for well crystalline phases, it is necessary to have the crystalline standards phase (crystalline references) considered 100 % crystalline.
The same sample phase is compared against that particular one to obtain the crystallinity index.
PVD material presents significant texture; that particular problem will increase the task difficulty.
Here in RG, you will find several examples of how to calculate the crystallinity of cellulose, for instance, from several sources and treatment procedures. Those particular pathways will give you a good idea.
Nevertheless, the first immediate task is to determine if some texture, preferred orientation is present in the deposited sample over each identified phase.
If so, it is mandatory to calculate the preferred crystallographic direction before any crystalline index calculation.
Best regards,
WNM
Wagner Da Nova Mussel Thank you for an insightful reply.
So when we incorporate certain carbon fillers in PVDF, with an aim to convert alpha phase to beta/gamma, we observe improvement in crystallinity (filler acting as nucleating agents); so what does it actually symbolize as in that beta/gamma phases are more crystalline than alpha phase? Because in theory we are only converting one crystalline phase to another. And why is it that films with only alpha phase are less crystalline than pure beta/gamma phase films?
Just curious thoughts!
Dear Akanksha Adaval ,
In principle, the described phenomenon is not uncommon.
However, in the first place is necessary to determine if what you call "improvement in crystallinity" is not related to the increase in the preferred orientation.
By increasing the alpha phase, you may be inducing preferred orientation. It may be happening despite only converting it to the beta/gamma phase.
It needs to be clarified.
However, if a single-phase conversion is confirmed since it is a PVD system you may be dealing with, an association of the subtract orientation (polishment).
That indicates that beta/gamma phases are growing in the same direction (preferred orientation).
If no preferred orientation is possible, an increase in crystallinity is the correct interpretation. Those phenomena must be understood and put apart.
Best regards,
WNM
That's an interesting way to put it.
I am just having a difficulty in grasping a relation between crystallinity and preferred orientation, as you mentioned.
Can you kindly elaborate in that?
Thank you for all the help you are providing!
Dear Akanksha Adaval ,
Check the substrate used for the PVDF deposition for a polishment along a specific crystallographic direction.
The observed increase in crystallinity may relate to the epitaxial relationship with the subtract.
In such a case, the preferred orientation is due to the primary substrate orientation.
Just in case the substrate has one different polished orientation, when compared with the PVDF, an increase in crystallinity is possible.
Another explanation would be the added phase has its particular preferred deposition direction.
Finally, if no epitaxial relationship is present and the deposited phase has no preferred orientation, the observed effect is related to the increase in crystallinity of the deposited phase.
Best regards,
WNM
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