(516g) Enhancing the Mechanical Performance of Polyolefin Blends through Solvent Annealing

Most mechanical recycling processes inadvertently reduce the molecular weight of commodity plastics due to chain scission under high shear high temperature environment. Addressing the presence of these low molecular weight fractions in a circular plastic economy remains a major challenge, as their incorporation into virgin materials often results in an increased number of unentangled chains, which compromises mechanical performance and overall material properties. In this talk, we will discuss a solvent-based annealing method that enables controlled mixing of low molecular weight polymer chains with their high molecular weight counterparts across various mass ratios. Using polypropylene as a model system, our approach can significantly improve mechanical properties in recycled plastics containing low molecular weight polymers. Our results reveal that swelling the amorphous regions of high molecular weight polyolefins facilitates the formation of trapped entanglements with shorter chains, enhancing material toughness without inducing plasticization. This strategy can be broadly applicable to different polyolefin systems and offers a promising pathway to upcycle plastic waste containing degraded, low molecular weight components.