Bioinspired Self-Healing Vitrimer from Epoxidised Palm Oil Reinforced with Nanofibrillated Cellulose and Activated Carbon

Abstract

A vitrimer composite based on epoxidised palm oil (EPO) was reinforced with nanofibrillated cellulose (NFC) and palm kernel shell (PKS)-derived activated carbon as complementary bio-based fillers. The loadings of NFC and activated carbon were varied to examine their influence on the thermal, mechanical, chemical, and healing-reprocessing behaviour of the EPO vitrimer network. The synergistic interaction between these fillers preserves dynamic bond exchange within the vitrimer network, enabling effective thermal welding in which the welded interface becomes seamless after treatment. This dynamic network behaviour was further reflected in dynamic mechanical and creep-recovery analyses, which revealed the influence of filler content on network mobility. A higher filler content (5 wt% of each filler) enhanced stiffness but restricted network rearrangement, leading to incomplete strain recovery. In contrast, the composite containing 4 wt% of each filler achieved complete strain recovery (100%) while exhibiting strong viscoelastic damping behaviour (tan d ~ 1.36), indicating efficient molecular relaxation during the glass-transition process. FESEM showed improved interfacial continuity within the synergistic system, where NFC extends between activated carbon particles and the vitrimer matrix to maintain local network integrity and facilitate stress transfer. The rigid carbon phase also limits solvent diffusion within the matrix, contributing to improved solvent resistance of the vitrimer composite.