Towards sustainable and recyclable plastic materials: Vanilin-based epoxy bio-composites with spruce bark powder and hydrochar, pioneering green chemistry solutions for shape memory applications

The negative impacts of fossil-based plastic production and its excessive usage are significant and multifaceted, affecting both the planet and humanity in various ways. In this study, a novel approach to developing sustainable and recyclable materials sourced from lignocellulosic biomass is introduced. This methodology involves formulating an epoxy-based resin using diglycidyl ether of vanillin (DGEVA) for curing with dodecenylsuccinic anhydride (DDSA), in presence of significant proportions (5–20 wt%) of either spruce bark (SB) powder or its hydrochar (HTC). Through thermomechanical analyses conducted via Dynamic Mechanical Analysis (DMA), it was ascertained that while the inclusion of SB has minimal impact on material performance, the incorporation of HTC leads to significant improvements. Specifically, a substantial enhancement in storage modulus is observed, increasing from 1.5 GPa to 3.1 GPa, and a rise in the damping factor from 56°C to 61°C. These findings are further corroborated by Scanning Electron Microscopy (SEM) analysis, which demonstrates excellent compatibility between the bioresin matrix and the biofillers. Moreover, this investigation underscores the remarkable mechanical and chemical recycling capabilities of the systems, which are notably improved by the presence of spruce bark or HTC particles, in addition to their inherent shape-memory properties. This approach not only showcases the feasibility of sustainable material development but also highlights the potential for an effective waste utilization in enhancing material properties and reducing the environmental impact.