Comparative Study of Polyethylene, Polypropylene, and Polyolefins Silyl Ether-Based Vitrimers

Abstract

Polyolefins (POs), which constitute over 50% of all plastics, predominantly end up in landfills. To date, there have been no reports on mixtures of PO vitrimers. This study reports the successful synthesis of PO vitrimers from a mixture of 27.7% high-density polyethylene (HDPE), 36.3% linear low-density polyethylene (LLDPE)/low-density polyethylene (LDPE), and 36.0% polypropylene (PP), which is similar to that of Municipal Solid Waste (MSW). This is achieved by using silyl ether-based chemistry, both with and without nitroxides. Additionally, these PO vitrimers are compared with individual vitrimers made of HDPE, LDPE, LLDPE, and PP, as well as vitrimers made from PE blends (comprising HDPE, LLDPE, and LDPE). All vitrimers were prepared via melt extrusion. Their cross-linking density, storage modulus, tensile properties, and reprocessability were assessed. For PO vitrimers, a storage modulus of 0.61 MPa was achieved, indicating a cross-linked network while also maintaining complete melt reprocessability. This study not only provides fundamental insights but also presents a sustainable pathway for recycling PEs and POs into useful materials, hence helping to minimize waste.