This highly rigid and sustainable TPU was synthesized using a conventional 2-step protocol from MDI, PTHF 650 (a medium-long polyether diol) and betulin (a rigid chain extender). The synthesis route is shown in Figure . Betulin is a cycloaliphatic terpene which can be obtained by chemical and/or biotechnological synthesis from sustainable resources such as plastic waste or biomass. The TPU rigidity is mainly provided by MDI and its aromatic rings and the betulin, which features 5 aliphatic rings. The obtained TPU is very brittle and has a high Tg (51 °C) as determined by DSC (Figure ). PHOhexyl and DPHP:DIDP were incorporated into TPU matrix as plasticizers at different content (Table )