Vitrimer bead foams: Cell density control by cell splitting in weld-compression molding

Abstract The fabrication of weldable and recyclable polyolefin bead foams remains a great challenge. Here, we report a convenient pathway to transform polyolefin elastomer (POE) into vitrimers based on classical ester-hydroxyl transesterification through reactive extrusion. The dynamic behaviors and mechanical properties of POE vitrimers could be readily regulated by varying the dosage of the cross-linker. POE vitrimer bead foams are prepared by a simple and feasible free foaming technology. We suggest two approaches to reprocess and recycle POE vitrimer bead foams by weld-compression molding and re-foaming. POE vitrimer bead foams could be well bonded with adjustable cell density and performance through weld-compression molding strategy. The dynamic transesterification can not only promote the fusion of foam beads, but also induce the fusion of contact buckling cell walls under compression. This investigation would motivate further sustainable development in the designing and recycling of polymer bead foams.