Novel biodegradable aliphatic copolyesters based on poly(butylene succinate) containing thioether-linkages for sustainable food packaging applications

Poly(butylene succinate) (PBS) based random copolyesters containing thioether-linkages were synthesized by melt polycondensation, and characterized from the molecular and thermo-mechanical point of view. Permeability to O2 and CO2 gases and biodegradation rate in compost have been also evaluated. The synthesized semicrystalline copolymers have proved to be thermally stable and characterized by PBS crystal phase. The main effect of copolymerization was a lowering in the crystallinity degree and a decrease of Tm with respect to homopolymer. The dependence of Tm on composition was described by Baur's equation. Slightly different surface hydrophilicity has been also displayed. Mechanical properties and the biodegradation rate turned out to be deeply influenced by the copolymers composition, in particular the higher the thiodiethylene glycol mol% the higher the elongation at break and the biodegradation extent. It is worth mentioning that the synthesized copolymers displayed better barrier properties to both studied gases with respect to commercial Poly(lactic acid).