How can you identify PP from FTIR?

Quick answer

PP is usually reported with a recurring pattern of peaks and functional-group evidence. The most useful approach is to cross-check at least two characteristic peaks before treating it as a match, then verify whether the full spectrum still fits the same material family.

Peak interpretation

Possible materials / groups

Spectrum logic

The logic here is evidence aggregation: repeated literature mentions of PP, repeated peak positions, and repeated functional-group associations. A strong material hypothesis should still be supported by multiple peaks that agree with each other, not by one headline band alone.

Real-world usage

This page is designed for polymer identification, incoming-material QC, unknown plastic analysis, recycled-content review, and literature-backed interpretation of reference spectra.

Common mistakes

• Calling a material match too early because one famous peak is present.
• Ignoring sample prep, fillers, oxidation, water, or additives that can change the apparent pattern.
• Using literature evidence without checking whether your own sampling mode and spectrum quality are comparable.

Verification advice

Use DSC, GC-MS, or TGA to validate the material hypothesis when the peak pattern is ambiguous or mixed.

Literature behind this page

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  Optical photothermal infrared spectroscopy with simultaneously acquired Raman spectroscopy for two-dimensional microplastic identification DOI: 10.1038/s41598-022-23318-2
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  Microplastic concentrations, size distribution, and polymer types in the surface waters of a northern European lake DOI: 10.1002/wer.1229
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  Murphy 等 - 2022 - Assessment of microplastics in Irish river sedimen DOI: 10.1016/j.heliyon.2022.e09853
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  Developing Post-Consumer Recycled Flexible Polypropylene and Fumed Silica-Based Nanocomposites with Improved Processability and Thermal Stability DOI: 10.3390/polym15051142
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  Birch 等 - 2021 - Isotope ratio mass spectrometry and spectroscopic DOI: 10.1016/j.talanta.2020.121743.
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  Pyrolysis kinetic behaviour and TG-FTIR-GC–MS analysis of Coronavirus Face Masks DOI: 10.1016/j.jaap.2021.105118
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  Nari 等 - 2021 - A comparative study on the thermal behaviour of PP DOI: 10.1016/j.matpr.2020.05.708
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  Kundu 等 - 2021 - Identification and removal of microand nano-plas DOI: 10.1016/j.cej.2021.129816.

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  Ajji 等 - 2005 - Biaxial orientation characterization in PE and PP DOI: 10.1177/8756087905056865

• PP

  Thermal Degradation and Organic Chlorine Removal from Mixed Plastic Wastes DOI: 10.3390/en15166058