Green recycling of aluminum plastic packaging waste by solid‐state shear milling and 3D printing for thermal conductive composites

Abstract

AbstractAluminum‐plastic packaging is a multilayer material composed of polymer and aluminum, which has been applied in food, medical, and other fields, due to the excellent fresh‐keeping and barrier performance. However, it is difficult to recycle aluminum‐plastic packaging waste (APPW) due to the complicated components and the low value of reclaim products. This paper reports a green way to recycle the APPW by solid‐state shear milling (S3M) technology and then fabricate APPW/expandable graphite (EG) composite parts with high thermal conductivity by fused deposition modeling (FDM) process. After the S3M treatment, the ultrafine APPW powder with the size of 7 ~ 8 um was obtained, and it showed excellent processibility and the APPW/EG composite parts were successfully processed by FDM technology. The APPW/EG three‐dimensional (3D) printed parts showed excellent mechanical and heat transfer performance along the stretch direction (0°), where the tensile strength and thermal conductivity reached 13.58 MPa and 2.71 W/mK for APPW/EG (80/20) composites, respectively, much higher than those of pure APPW composite (7.71 MPa and 0.62 W/mK). Theoretical calculations showed that the interfacial thermal resistances of APPW/EG 3D printed parts with aligned fillers were lower than other samples. Furthermore, the APPW/EG composites with 20 wt.% EG loading showed a low electrical conductivity of 10−10 S/cm because the oxidation layer was formed on the surface of Al flakes during the S3M process, which can be used in the thermally conductive insulating field. The new strategy presented in this work provides a new sight to recycle APPW for value‐add material.