Chemical depolymerization has been identified as a promising approach towards recycling of plastic waste. However, complete depolymerization may be energy intensive with complications in purification. In this work, we have demonstrated upcycling of mixed plastic waste comprising a mixture of polyester, polyamide, and polyurethane through a reprocessable vitrimer of the depolymerized oligomers. Using poly(ethylene terephthalate) (PET) as a model polymer, we first demonstrated partial controlled depolymerization, using glycerol as a cleaving agent, to obtain branched PET oligomers. Recovered PET (RPET) oligomer was then used as a feedstock to produce a crosslinked yet reprocessable vitrimer (vRPET) despite having a wide molecular weight distribution using a solventless melt processing approach. Crosslinking and dynamic interactions were observed through rheology and dynamic mechanical analysis (DMA). Tensile mechanical studies showed no noticeable decrease in mechanical strength over multiple repeated melt processing cycles. Consequently, we have clearly demonstrated the applicability of the above method to upcycle mixed plastic wastes into vitrimers and reprocessable composites. This work also afforded insights into a potentially viable alternative route for utilization of depolymerized plastic/mixed plastic waste into crosslinked vitrimer resins manifesting excellent mechanical strength, while remaining reprocessable/ recyclable for cyclical lifetime use.

化学解聚已被认为是塑料废物回收利用的一种有前途的方法。然而，完全解聚可能是能源密集型的并且纯化过程中也很复杂。在这项工作中，我们展示了通过解聚低聚物的可再加工玻璃三聚体对包含聚酯、聚酰胺和聚氨酯混合物的混合塑料废物进行升级回收。使用聚对苯二甲酸乙二醇酯（PET）作为模型聚合物，我们首先演示了部分受控解聚，使用甘油作为裂解剂，以获得支化 PET 低聚物。然后，回收的 PET (RPET) 低聚物被用作原料，通过无溶剂熔融加工方法生产交联但可再加工的玻璃体 (vRPET)，尽管它具有较宽的分子量分布。通过流变学和动态机械分析（DMA）观察交联和动态相互作用。拉伸力学研究表明，在多次重复的熔融加工循环中，机械强度没有明显下降。因此，我们清楚地证明了上述方法将混合塑料废物升级为玻璃体和可再加工复合材料的适用性。这项工作还提供了一种潜在可行的替代途径，将解聚塑料/混合塑料废物利用成交联的 vitrimer 树脂，表现出优异的机械强度，同时保持可再加工/可回收以供循环寿命使用。