Fig. 7
The 1H NMR spectra of gutta percha from Tjipetir 1917 (RS1-RS3) and fresh latex from Cipetir (CI 2015) show characteristic spectral features for trans-polyisoprene, confirming gutta percha. Even though samples RS1-RS3 were from 1917, the block remined under water, which protected it against exposure to oxygen. The new material from the same factory, produced in 2015, was exposed to air and showed the presence of oxidation products. Regardless of the samples’ age, 1917 and 2015, all spectra indicated gutta percha, showing a double set of peaks at 1.95–2.10 ppm for the CH2 groups. An inset in the upper part shows the molecules’ stereochemistry related to the position of the functional group in a molecule of trans-polyisoprene