Thesis title: Study, design & development of compostable and recyclable elastomers with a high degree of innovation, technological content and low environmental impact
PhD research aim is to design and develop a bio-elastomer with high degree of innovation, technological content and low environmental impact. The research is restricted to the industrial field of automotive applications, focusing on thermoplastic elastomers (TPEs) for o-rings manufacturing. The project focuses on conceiving an eco-friendly elastomer, driven by necessity to mitigate TPEs environmental impact related to their conventional fossil-based nature and disposal.
The research project is a collaboration between Sapienza Università degli Studi di Roma, Department of Mechanical and Aerospace Engineering, and Tresearch S.r.l., an innovative start-up acting as an industrial partner.
The first step has been to investigate bio-based, biodegradable and compostable materials for prototype formulation definition. Three blends have been conceived, selecting a PLA matrix as primary biopolymeric phase. The addition of a liquid biodegradable plasticizer (Acetyl Tributyl Citrate-ATBC) and/or of a secondary biopolymeric phase (P3HB4HB-PHACT) was assessed to improve the flexibility and the elongation of PLA, aiming to design a bio-elastomer with complete elastic recovery. On this point, the three formulations have been respectively named as PLA/ATBC, PLA/PHACT, PLA/PHACT/ATBC.
Once formulations have been defined, compounding was conducted via co-rotating twin-screw extruders for lab-scale pellet production. The three blends have then been fed to a single-screw cast extruder for sheet forming. Along with extrusion processes, compound and sheet characterization has been performed: thermal (DSC) and rheological tests (MFI, Rheometer) to characterise the experimental compounds as well as tensile tests on the sheets to evaluate materials elastic behaviour. Based on the analysed performances, PLA/ATBC compound has been identified as prototype bio-elastomer.
Finally, a Life Cycle Assessment (LCA) has been carried out to compare environmental impact of the prototype bio-elastomer with a traditional TPE derived from fossil sources (EPDM). Following a cradle-to-grave approach, the environmental impact generated from life cycle single phases of both materials has been assessed and a full comparative LCA performed.