Fig. 11

The IR spectra generated with Raman of the known gutta percha samples processed in the same factory, 100 years apart; Tjipetir (dated 1917: samples RS1, RS3) /Cipetir (CI2015, top and bulk), and model trans-polyisoprene. The peaks assigned by researchers as characteristic of trans-polyisoprene in the regions 800–900 cm⁻¹ and 1100–1200 cm ⁻¹ are present in most samples but are not dominant, as the literature suggests