Natural Cork Suberin-Originated Ecofriendly Biopolyester Syntactic Foam

Depolymerized suberin derivatives (DSDs) isolated from cork powder, the industrial waste, were used for the synthesis of an ecofriendly biopolyester (pDSDs) syntactic foam along with expandable microspheres (EMs). Its potential for replacing the conventional petroleum-based polymer was demonstrated, and renewable resources were suggested. In this study, the optimum amount of glycerol (5.77 wt %) to meet the stoichiometry in DSDs polyesterification was determined with ¹H NMR. By engineering EMs, the cell size and porosity of syntactic foams were controllable, and the mechanical properties were characterized. The specific compressive modulus of this syntactic foam was raised up to 66% when EMs were filled from 20 to 30 wt %. Viscoelastic properties of syntactic foams were characterized by varying the weight fractions of EMs and the EMs' size. It should be noted that the tan δfor syntactic foams with DSDs was found to be greater than the one of natural cork (up to 124%) from -50 to 80 °C. Encouragingly, the biopolyester syntactic foams synthesized with suberin extracted from the cork powder can offer a new way to reduce carbon footprint by recycling industrial waste and replacing conventional petroleum-based polymeric foams.