The novel application of nonmetals from waste printed circuit board in high-performance thermal management materials

Abstract

Nonmetals from the waste printed circuit board (NPCB) is the byproduct of waste printed circuit board recycling industry. The recycling of tons of NPCB for a clean environment and value-added product is still a great challenge. In this work, the possibility and feasibility of using NPCB to fabrication value-added thermal management materials are evaluated for the first time. The mechanical properties, thermal conductivity, dielectric performance and heavy metal leachate were studied. Due to the high aspect ratio of NPCB, the maximum tensile strength of LDPE/GNP/NPCB composites are increased from 24.9 MPa to 36.2 MPa and storage modulus maintained at 1403 MPa in 100 °C. Such data is much higher than those reported in the literature for LDPE/GNP composites and shows great potential for thermal management products. When increased NPCB content to 50 wt%, finite element simulation indicated that graphite nanosheets (GNP) interconnect and more heat flux is propagated through thermal conductive filler. The maximum thermal conductivity of LDPE/GNP/NPCB composites is increased from 1.0 W/mK to 1.6 W/mK. Moreover, the electrical conductivity of all samples is above 109 Ω cm, and the composites show low dielectric permittivity and dielectric loss, meeting the requirements of insulating and thermally conductive materials. The heavy metal leaching results show that after 20 days, the concentrations of Cu, Zn, Pb, Ba, Cr, and Ni ion are far below the regulatory limits. This work not only provides a promising strategy to resolve NPCB environment pollution but also value-added products in thermal management applications.