Please how to calculate carbonyl and vinyl indices of PE and PP plastics from FTIR spectra? What are the characteristic peaks to be considered for PE and PP?
To calculate the carbonyl and vinyl indices of polyethylene (PE) and polypropylene (PP) plastics from FTIR spectra, follow these steps:
Carbonyl Index (CI)
Peak Identification:
PE: The carbonyl peak falls in the range of 1850–1650 cm-1
PP: The carbonyl peak falls in the range of 1,850–1,650 cm-1
Peak Area Calculation:
Use the specified area under the band (SAUB) methodology, which involves measuring the area under the carbonyl peak and comparing it to a reference peak.
CI Calculation:
CI = Area of absorption peak of carbonyl bond / Area of absorption peak for reference bond.
Vinyl Index
Peak Identification:
PE: The vinyl peak falls in the range of 1495–1423, 1460, and 1452 cm-1
PP: The vinyl peak falls in the range of 1504–1467 and 986–952 cm-1
Peak Area Calculation:
Use the specified area under the band (SAUB) methodology, which involves measuring the area under the vinyl peak and comparing it to a reference peak.
Vinyl Index Calculation:
Vinyl Index = Area of absorption peak of vinyl bond / Area of absorption peak for reference bond.
This provides a more accurate and standardized way to quantify the degradation of these plastics over time.
Dear Abdelhak,
thank you very much for your kind and detailed reply!
Best Regards
Marcella
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