Reconfigurableshape memory properties of recycled polyvinyl butyral materials through dynamic covalent bonds

This study investigates the shape memory and reconfigurability behaviors of recycled polyvinyl butyral (RPVB) with partially extracted plasticizer, which is crosslinked using hexamethylene diisocyanate (HDI) and a catalyst, dibutyltin dilaurate (DBTDL). The use of RPVB, a recycled plastic, is significant as it contributes to sustainability by reducing waste and promoting the reuse of plastic materials. The effect of HDI content on the shape memory performance of RPVB was explored, with emphasis on the catalyst's role in enhancing its reconfigurability. RPVB-20, with 20% plasticizer extraction, exhibits excellent shape fixation at room temperature, with a shape recovery rate (R r ) of 81.2%, which increases to over 95% after HDI crosslinking. The addition of DBTDL further improves the material's reconfigurability, enabling it to adopt new permanent shapes through dynamic covalent bond exchange at 160 °C. The material demonstrates good shape memory performance with an R f of 99.4% and an R r of 96.9% when 0.2 phr HDI is added. Stress relaxation and creep tests show that the catalyst accelerates urethane exchange, providing plasticity at elevated temperatures. Furthermore, RPVB-20-0.2-DL exhibits excellent reprocessing properties, with stable mechanical properties after reprocessing, making it suitable for manufacturing permanent three-dimensional shapes and for potential recycling applications. The results suggest that dynamic covalent bonds in RPVB shape memory polymers offer both high reconfigurability and stable mechanical properties, providing a promising approach for sustainable material design in smart applications while promoting the recycling and reusing of plastic materials in line with environmental objectives. Graphical