I think the reason is that your polymer became amorphous. In this case the XRD peaks of the polymer drastically diminuished or, in the extreme case, disappear.

Thank you, Anna Tinti. But, can a low molecular weight substance at even 10% loading cause such a drastic effect in a semi crystalline polymer matrix? It was kind of shocking to me, when I saw the XRD patterns. When i get to the lab computer, I will send the xrd pattern, possibly you could make some sense out of it. 

Sorry, but I am not an expert of XRD technique and I dont think to can help you in this. I have studied biomaterials by other techniques (IR, Raman) and I know that in some cases polymers can become practically amorphous to XRD but mantain IR and Raman spectra, even if with a halfwidth of their bands increased. If you have the possibility to make an IR spectrum of the material before and after loading, perhaps you can control if this behaviour is yours.

Could you please send me the XRD pattern. May be I can help

First verify that you don't have a technical problem with your XRD.

As Anna said, the incorporation of filler in a polymer may change the blend properties even the load of filler is low. Sometimes, it is better to use the volumic % rather then the weight%. Even if you have 10w% of filler, if its density is too low, the volumic% is very high, then you have the filler everywhere in you blend which decrease the possibility to polymer cristallization.   

Dear Ganesh Narayanan,

Some preliminary remarks:

1. 'Why' questions belong rather to philosophy or religion than to science.

2. It seems that for the question posed volumefraction is more significant than weight fraction.

3. However, temperaturevariations during blending may alter the crystaliinity of the high molecular weight polymer.

4. Corrobating evidence could be obtained by studying the Young's modulus as a function of temperature for different blend compositions.

References:

1. Pieter van Mourik et al, Materials Science in Design and Engineering, DAP/VSSD, Delft NL, 2012, p. 244

2. A.K. van der Vegt, From Polymers to Plastics, DAP/VSSD, Delft NL, 2006

Hi everyone!

Were the fibers produced by wet or melt electrospinnig?

For the first case, the residual solvent is the main cause for the crystallinity loss of your sample, for sure. 

For the second case, the very fast cooling process do not allowed for the crystalline domains formation. So, you might need to anneal the sample...

Nevertheless, 10% of loading is too much to preserve the properties of a polymer matrix…

Generally, polymer samples having an amorphous nature show peak broadening and less intensity peaks.It also depends on polymer host and doppent which you choosen.

Hi again!

Well, the amorphous part of the material should show up around 5 to 4 A distance (depends on the polymer repeating unit) as a broad peak which correlates around the same distance (no correlation at all). For a crystalline polymer, the peak should be sharper and correlates 10 or 100 times the d-spacing of the peak (depending on the size domains).

The intensity has nothing to do for the crystallinity evaluation of the sample. Actually, the area should be the same for the same sample when crystalline, semi-crystalline or amorphous since the intensity has to do with the scattering length density which is almost the same for amorphous or crystalline state.

That's the reason why you can evaluate the degree of crystallinity of your sample by X-ray!

SALUT!

it's not easy answer without looking the xrd spectra. Any way try this check list:

1) Do the peaks's FWHM increase? --> more strain smaller cristalline size

2) Do the peaks's area decrease and a broad low angle signal similar to background appears around 5-10 2theta? less crystalline phase more amorphous

3) The FWHM remain more or less the same or decreases the ratio among the peaks changes, some peak increase other peaks decrease: The sample is not randomly oriented during the polymerization it became oriented in some direction typical for the fiber.

Sorry, I could not follow up for quite some time. Here are the raw materials. 

polymer=Polycaprolactone (density is slightly higher)

Filler=Beta cyclodextrin

Filler %=10 to 40%. peak intensity of PCL decreases right on from 10%

Fibers prepared by wet electrospinning. Solutions were prepared at high temperatures (80C) but electrospun at room temperatures. 

@Ejaz ahmed, I can send the files, but what format would like it to be in? @ Nisha I hope I had given complete information. 

Please attached the XRD image. The ones that I am interested are third and fourth one, from top. i.e., 10% and 30% Beta CD

Dear Ganesh,

The peak intensity might change also due to the thickness of your sample: be careful. If the thickness of the sample was the same, then the change in intensity is due to i) increase in population of an amorphous component (beta-CD) and ii) the disorder induced effect due to the presence of such impurity. Did you perform any TEM image in order to elucidate whether there is a good dispersion or aggregates of beta-CD in the PCL matrix? If there are aggregates, then no effect should be observed. But, if there is a good dispersion, then is getting a little bit more complicated.

The beta-CD looks quite amorphous, and I do not believe there is a strong interaction between the two components. Do you expect hydrogen bonding between the OH groups from the sugar and the esters from the polymer? Any evidence for that? FTIR? So, by adding more beta-CD you should reduce the intensity of the PCL peaks, that's all.

Said this, the FWHM of the two major peaks in PCL should not change that much, but the intensity should. I also see a shift in the second upper curve. Did you place correctly the sample?

For the rest, I offer myself to analyze your data if you need some assistance. In this case, please send me also the wavelength of your source.

Hope you got it.

SALUT!

Tony 

Dear Ganesh Narayanan, 

Let us first obtain agreement about observations; therefore I make some preliminary remarks:

1. beta-CD powder is clearly amorphous.

2. (semi)crystalline peaks for the blends are signifantly lower than for the neat PCL -mat.

3. 10% and 30 % beta-CD nanoweb show spreaded-out peaks at 2-theta positions corresponding to the neat PCL mat

4. the 40% alpha-CD nanoweb shows a shift to higher two-theta-values and the emergence of  a new peak on the lower two-theta side of the main peak.

Question: is there a difference between alpha and beta CD nanoweb?

Addtional remarks;

1. total diffracted intensity as the surface below the peaks only depends on the X-ray source.

2. ratio's of  integrated intensity diffracted by different phases is the basis for the X-ray diffraction based determination of the volume fraction of retained austenite. 

3. Your data suggest that on blending with 10 % beta and 30 % beta CD nanoweb the volumefraction of the amorphous part of your samples increases.

4. Your data also suggest that for the case of 40% alpha-CD nanoweb diffraction occurred at new distances related to the nature and the extent of semi-crystallinity.

Repeated suggestion:

Obtaining corrobating evidence, e.g optical microscopy or studying Young's modulus as a function of temperature and blend composition

@ Antoni: From the literature as well, i understand, as you had mentioned, the decrease in the intensity could be due to the impurity (B-CD). I did not perform TEM to understand further, with that said, I did XPS for a different purpose, and what I understand is that, b-CD is populated highly in the surface (by virtue of OH in XPS spectra). And also, higher aggregates are not expected. i expect them to be seperated by a good distance, and as you had mentioned that could be a good reason for such drastic decrease in intensity. 

Higher interaction vis hydrogen bonding is not expected with PCL. PCL is highly hydrophobic, and should retard any such interaction. FTIR doesnt show any such interaction. While I performed XRD, I did not worry about the thickness (which I should have), also, since my intention is not to study the crystallite size, I did not worry about FWHM. I have the data in the computer, and I can happily provide the data. The radiation source was 1.54 A. Please let me know, if you need further data or spectra.Although, this analyses doesnt make a significant portion of my thesis, as a scientist, I am very curious to understand the mechanism. 

@ P.Van Mourik: i agree to all of your preliminary remarks. My answer to your question is, cyclodextrins are ring shaped sugar molecules, and a-CD and b-Cd are two different types with 6 and 7 sugar molecules, respectively. There is one difference in the mat, which I forgot to mention. PCL/a-CD was electrospun at a feed rate of 0.5 ml/hr, whereas, PCL/b-CD was electrospun at 1 ml/hr. I had to change it because, b-CD was precipitating and clogging the needle. 

You are right, in 40%a-CD web, diffraction occurs at different 2theta values, that is due to the formation of new crystal structure. i.e., some PCL chains have threaded into the cavity of the a-CD, whereas, that phenomenon is not expected in case of b-CD because, PCL chains are kind of unstable in the cavity. From all the interaction I had through research gate, most plausible reason in my opinion is that, b-CD profuses onto the PCL surface, thereby exhibiting higher amorphous nature to the web.