Local mechanical invariance in a recycled biobased vitrimer - evidence from the vibrational density of states.

Abstract

Biobased vitrimers represent a promising class of recyclable thermosetting polymers due to their dynamic covalent networks. In this study, the local mechanical properties of a vitrimer system based on glycerol triglycidyl ether and a vanillin-derived imine hardener are investigated before and after recycling. Using inelastic neutron scattering, the low frequency vibrational density of states is analyzed, focusing on the Boson peak (BP) as a sensitive probe of local elasticity. The vitrimer exhibits a pronounced BP, with its position and shape remaining unchanged after recycling, indicating that the local elastic modulus is preserved. Comparison with the BP of poly(methyl methacrylate) reveals a higher maximum frequency of the Boson peak and lower Debye level for the vitrimer, suggesting a higher transverse sound velocity and shear modulus. These findings demonstrate that the recycling process does not compromise the microscopic mechanical integrity of the biobased vitrimer during a recycling process, supporting its potential for sustainable material applications.