Eco-friendly recyclable high performance ramie yarn reinforced polyimine vitrimer composites

The huge and increasing amount of plastic waste harms wildlife and releases chemical hazards to the environment. Using cellulosic fibers to prepare natural fiber-reinforced plastic composites (NFRPCs) is a promising strategy to decrease plastic wastes and lower their negative impacts because cellulosic fibers are renewable, degradable, and conducive to carbon neutrality. However, the low tensile strength and recycling difficulty of NFRPCs prevent them from substituting nondegradable plastics on an industrial scale. This study prepared high-performance ramie yarn-reinforced polyimine vitrimer composites (RY-PI) that could be recycled both chemically and physically. The polyimine matrix formed a robust bonding interface with ramie yarn via hydrogen bonding. The tensile strength of RY-PI (144 MPa) was superior to that of most NFRPCs available in the market and was the highest amongst the NFRPCs with the same fiber fraction (wt%). RY-PI was also lightweight and had good toughness, self-healing ability, moldability, durability to organic solvents, and moisture barrier resistance. A box prepared by four-layer RY-PI laminates could support more than 3,000 times its own weight. The RY-PI was closed-loop recycled through a chemical strategy without any loss of performance. More importantly, a highly efficient (11 min for each recycling), low-cost, and eco-friendly (without adding any chemicals) physical recycling method of RY-PI was demonstrated. RY-PI could be physically recycled at least 9 times without any loss of performance. The high performance and good recyclability of RY-PI make it a promising environmental-friendly alternative to many conventional plastic products to help achieve zero plastic waste.