NIR and Raman spectra of transparent plastic materials
Polystyrene (this page) - Polypropylene - PET - Polyethylene - Miscellaneous plastics - Spectra with PbS detector
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To test the spectrometer in particular in the NIR, I have recorded the
spectra of transparent plastic objects of the everyday life. They are
reported in the 5 pages mentioned on top of this page. The Raman spectra
have been added whenever possible if the fluorescence was not too
high. In particular, the CH band of the Raman spectra could be compared
to the NIR spectra which are overtones and combination bands of the CH
vibrations of the material. I have also used a low resolution Foxboro
infrared spectrometer in the CH band region close to 3000 cm-1. I have used the Fytik software to deconvolve
the IR spectra. If the thickness is too high for the infrared
spectrometer, the plastics have been molten on a microscope slide. Below
is a collection of polystyrene spectra of small objects. The band at
2100 - 2200 nm is mainly an aromatic ring CH stretching vibrations also seen in
Raman in the region 2800-3200 cm-1. It is also found in Lego toys as
proved by the Raman spectrum below.
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| Several transmission NIR spectra of small transparent objects. The material is identified as polystyrene. The NIR spectra are quite similar to each other. The band at 2150 nm is indicative of the aromatic C-H bonds. |
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| Raman spectra of polystyrene objects. The stretching C-H bands at 2800-3200cm-1 are also indicative of the presence of aromatic and aliphatic C-H. |
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| Below is the Raman spectrum of a LEGO white brick. Spectra are similar to the polystyrene although some additional peaks are visible in the spectrum may be due to a filling added to the plastic material to give the white color. The C-H stretching spectra at 2800-3200cm-1 are quite similar. |
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