Synthesis and characterization of elastomeric, biobased, nonisocyanate polyurethane from natural rubber

Linear and crosslinked polyhydroxyurethanes (PHUs) based on natural rubber (NR) were synthesized by a polyaddition reaction without a solvent or catalyst to exploit the reactivity of diamines or triamines with dicyclic carbonate groups. Oligo-isoprenes were obtained from the controlled oxidative degradation of NR and successive modifications of the chain ends. The syntheses of linear PHU were carried out with two approaches. The first one consisted of a reaction between amino telechelic oligo-isoprenes and aromatic or aliphatic dicyclic carbonates. The second approach proceeded through a reaction between oligo-isoprenes bearing cyclic carbonate chain ends and difunctional or trifunctional amines. The evolution of these reactions was studied by Fourier transform infrared spectrometry. The influence of the carbonate-to-amine molar ratio, the chain length of the oligo-isoprenes, and the reaction temperatures were investigated. The thermal properties of the PHUs were studied by differential scanning calorimetry and thermogravimetric analysis. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45427.