Tuning the thermal, mechanical, and environmental performance of bio-based aromatic–aliphatic copolyesters for sustainable railway damping applications

Abstract

The transition from fossil-based to bio-based polyesters is imperative to address environmental concerns. The synthesis and characterization of novel bio-based copolyesters derived from 2,4-dihydroxyacetophenone are reported in this study. A key diol monomer, 1-(2,4-bis(4-hydroxybutoxy)phenyl)ethan-1-one (BPEO), was synthesized and subsequently copolymerized with hydroquinone bis(2-hydroxyethyl) ether (HBHE) and aliphatic diacids (succinic/adipic acid) to produce PBHS and PBHA, respectively. The structure-property relationships of these copolyesters were systematically investigated. Increasing the aliphatic diacid chain length from C4 to C6 reduced the glass transition temperature (from 79 °C to 71 °C) and thermal stability, while slightly enhancing ductility. Both amorphous copolyesters showed significant mass loss (5.59–6.08 %) after 32 weeks in soil, with degradation rate correlating to aromatic content. Crucially, acute ecotoxicity tests on earthworms ( Eisenia fetida ) demonstrated very low toxicity, with survival rates exceeding 90 % even at high concentrations (5000 mg/kg). This work provides a series of promising bio-based copolyester materials with tunable properties, demonstrable soil degradation, minimal environmental ecotoxicity, and demonstrating potential as sustainable alternatives for industrial damping components such as railway elastomer buffers.