ISO 4650:2012 specifies two methods for the identification of rubbers, including thermoplastic elastomers, either in the raw state or in the form of vulcanized or unvulcanized mixes. The first method is based on infrared spectrometric examination using the transmission technique. The second method makes use of analysis by reflectance.

A comparison of the spectra resulting from reflectance (attenuated total reflectance, ATR) and transmission (film) is given.

Both methods comprise examination of polymers by their pyrolysis products (pyrolysates), or by films cast from solution or obtained by moulding (for raw rubbers only).

Typical spectra are given.

The methods specified are qualitative methods only.