Effect of Al₂O₃ fibers on the thermal conductivity and mechanical properties of high density polyethylene with the absence and presence of compatibilizer

Alumina (Al 2 O 3 ) fiber/high density polyethylene (HDPE) composites were prepared by molding injection with or without compatibilizer, in which, maleic anhydride‐grafted polyethylene (PE‐ g ‐MA) and acrylic acid‐grafted polyethylene (PE‐ g ‐AA) were used as the compatibilizers. The thermal conductivities of the composites were anisotropic and the conductivities in the injection direction of the samples were higher than those in perpendicular direction of the injection. The anisotropic thermal conductivity for Al 2 O 3 /PE‐ g ‐AA/HDPE was the most obvious and this composite also gave the best mechanical performance. The SEM and DMA test revealed that PE‐ g ‐AA was more effective than PE‐ g ‐MA in improving the matrix–filler interaction. The high interfacial interaction was more favorable for the viscous flow‐induced fiber orientation, which resulted in the largest anisotropic degree of thermal conductivity of the Al 2 O 3 /PE‐ g ‐AA/HDPE among the studied composite.