The images above show a cross-section through a perforated elastic film used in medical and sanitary applications. The film was embedded in an epoxy resin block and cut using a microtome. The mounting resin can be seen on the right of the image and a 5 µm thick surface layer can be seen between the bulk of the film and the resin. Localised thermal analysis of this layer (marked with a cross on the images) is shown below. The melting point of the polymer suggests that the outer layer is made of polyethylene.

The bulk of the film is known to be a rubber of some type. The thermal probe was used to pyrolyse this region and the evolved gases were analysed by GC-MS. The resulting chromatogram (below) detected butadiene dimer and trimer as well as styrene. This suggests that the polymer is the synthetic rubber - poly(butadiene-styrene) - rather than natural rubber.