Interpret the infrared spectra of the unknowns to confirm the
deductions from the other tests.
The following points may be helpful:
• IR spectra of some common polymers may be found on pages 8-13,
and on a range of web pages.
• You can identify a polymer by comparing the unknown and known
spectra, taking account of the overall shape of the spectrum – the
number and relative intensities of the bands – and the energies
(wavenumber in cm–1; equal to the inverse of the wavelength) of the
major bands.
• You do not need to identify all of the bands in the spectra,
although some may be assigned to particular types of molecular
vibration; e.g. C–H stretches near 3000 cm–1.
• Remember that some polymers may be blends, or be compounded
with other materials, and this may ca
use extra bands in the spectra. Important: Please explain the
reasoning behind your identification of each unknown polymer.
Remember to specify what each unknown was used for.
- Interpret The Infrared Spectra Of The Unknowns To Confirm The Deductions From The Other Tests The Following Points May 1 (83.19 KiB) Viewed 17 times
- Interpret The Infrared Spectra Of The Unknowns To Confirm The Deductions From The Other Tests The Following Points May 2 (379.57 KiB) Viewed 17 times
Experiment 2: Identification of Plastics pieces *** Material Observations Does material Does material burn What is the What is the Are there Standards melt? after being removed flame odour? residues after Unknowns from flame? colour? material was burned? Nylon Yes - it initially Upon removal from Orange, blue Smoky odour Yes - a charred browns, eventually flame the material edges pool of melted chars and melts extinguishes itself. nylon. while burning Polycarbonate Yes - also releases Yes - it burns rapidly Orange Phenolic odour Yes - a layer of (PC) black smoke whilst and then extinguishes soot and charred burning. on removal pools of melted PC. Polyethylene Yes - softens, melts Yes - it burns slowly Orange Sweet smell Yes - melted Terephthalate and drips. It also on removal. brown drips.** (PET) browns during burning Poly(methyl Yes - initially Yes - it bums slowly Yellow, blue Sweet smell Yes-charred, methacrylate) softens, the slowly on removal. centre melted (PMMA) melts and drips. Some charring. Polyethylene Yes - melts and Yes - it burns on Yellow, blue Candle-like Yes-pool of chars. removal centre odour charred liquid. Polystyrene Yes - melts and Yes - it burns on Yellow Styrenie odour Yes - layer of chars. removal. sool and charred, melted pieces.' Polypropylene Yes - melts and Yes - it burns on Yellow, blue Candle-like Yes-pool of (PP) drips. removal centre odour charred, melted liquid." Polyvinyl No-it burns and Yes - it burns on Bright green HCl odour Yes - charred chloride (PVC) chars. removal and piece. extinguishes itself. Spray bottle cap Yes - melts and Yes - it burns on Yellow with Candle-like Yes - pool of drips. removal and eventually hint of blue odour slightly charred, extinguishes itself. melted liquid Pen cap clip Yes - melts and Yes - burns rapidly on Orange Pungent smoky Yes - a layer of releases black removal and slowly odour soot and pool of smoke when extinguishes itself. charred, melted burning. plastic Ventolin puffer Yes - melts and Yes - continues Yellow Candle-like Yes-pool of lid drips. melting and rapidly odour melted liquid. extinguishes itself. Water bottle cap Yes - melts and Yes - it burns and Bright Candle-like Yes-pool of drips. continues to melt on orange odour melted liquid. removal *Please note: some observations which weren't tested in the laboratory were filled in using Table 1: Identification of Polymers - Heating and Combustion Tests from the Lab Manual and other references (see below).
Pen cap clip IR spectrum: 3000 1100 3200 100
Ventolin puffer lid IR spectra: 1000 3400 2009 3000 2400 1200 2000 2000 1800 1600 300 1400 1200 1000 000
Water Bottle Cap 100 98 96 94 Transmittance [%] 92 90 88 3800 3600 3400 3200 3000 2800 2600 1800 1600 1400 1200 1000 800 600 400 2400 2200 2000 Wavenumber cm-1
Spray bottle cap IR spectrum: 3 Whil 3400 3000 2000 1300 1000 1400 1300 000 300 000 400