To measure the rate of polyethylene in the EPDM I used the FTIR measuring the surface area of each peak but the problem in the EPDM there is polyethylene and polyproylene so there will be an interferent of -CH2 polyethylene and -CH2 polypropylene.
as you see from the FTIR peak
ref:
https://www.rado-rubber.com/specialities/epdm/#:~:text=Characteristics%20of%20commercial%20EPDM%20rubber,the%20best%20low%2Dtemperature%20flexibility.
"The ethylene content of commercial ethylene-propylene-diene rubber is between 45 and 75 percent. Grades with an ethylene content of 45 to 55 weight percent are amorphous and offer the best low-temperature flexibility. If the ethylene content rises, the crystallinity increases too. EPDM grades with an ethylene content of 55 to 65 weight percent are partially crystalline. Terpolymers containing more than 65 weight percent ethylene have larger crystalline regions and behave like thermoplastic elastomers; even in the uncured state their tear strength is very high.
The diene content of commercial products is between 2 and 12 weight percent. This corresponds to 3 to 16 double bonds per 1000 carbon atoms. A higher diene content leads to a higher crosslinking rate, higher strength values and a lower permanent deformation. By contrast, the weathering, ozone and ageing resistance drops as the diene content increases."
Relative measurement of standard's crystallinity via DSC and SEM vs your sample will reveal %.
Dear Hakim,
You might might use the band at 1376 cm-1.
Both polymers polyethylene (PE) and polypropylene (PP), have strong bands near 2950 cm-1 due to CH2 and CH3 stretching (symmetric and asymmetric) and near 1460 cm-1 due to CH3 deformation. The last one comes together with a band around 720 cm-1 from CH rocking.
However, if PE is branched or in the case of PP, bands near 1380 and 1365 cm-1 appear. In your spectrum you can see the sharp peak and a shoulder. The peak at 1380 cm-1 is ofter assigned to the symmetric bending of the methyl group (umbrella mode) in the side chains, whereas the peak at 1360 cm-1 is assigned to a vibrational mode of the methylene group.
You might make use of (1) FTIR spectra of linear PE, of PP, and of your samples for comparison, (2) fit a superposition of at least two Gaussians to the 1380 cm-1-band in order to extract the areas under the curve of the particular peaks, and (3) calculate the ratios of these areas in order to estimate the PE:PP ratio.
Best regards,
Markus Anton
Source: G. Socrates, Infrared and Raman Characteristic Group Frequencies, Tables and Charts, Ltd, 3rd edition, John Wiley & Sons, 2001, Chichester
PS: For the next measurements you can perhaps record the background spectrum directly before recording the spectra of you samples. This might reduce the spikes of the gaseous water rotation (1800-1500 cm-1 and 3950-3550 cm-1).
Dear Anton,
that's exactly the method I used, thank you for your reply
Arthur Markus Anton
Emilio Malaguti
Dear Emilio,
in this case i don't have a referent sample, thank you for your answer.
H.BOUT
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