Polyethylene-derived high-yield carbon material for upcycling plastic wastes as a high-performance composite filler

Abstract

In this study, to address environmental challenges stemming from plastic wastes, we produced carbon material derived from polyethylene (PE-C) using thermal oxidation and carbonization processes. Prior to thermal oxidation, e-beam irradiation was employed to enhance oxidation reactions which facilitated transformation of linear chains to cyclic ladder structures, resulting in a threefold increase in carbonization yield compared to conventional methods. Our analysis using XRD, Raman spectroscopy, XPS, and SEM revealed that PE-C exhibited a crystal structure similar to commercial CB (C-CB). However, it featured three times more oxygen functional groups on its surface and consisted of individual particles without forming aggregates or agglomerates. We incorporated PE-C into a PA6 polymer matrix to create composite materials with various compositions, systematically comparing their electrical, thermal, and mechanical properties to C-CB/PA6. PE-C outperformed C-CB in terms of mechanical properties (65 MPa vs. 41 MPa) due to its surface oxygen functional groups, uniform dispersion even at high loadings, and a rough surface. Moreover, PE-C exhibited a lower surface area, which reduced interfacial thermal resistance and consequently enhanced thermal conductivity, resulting in a 16 % improvement compared to C-CB at 30 wt%.