Fabrication of a high-density polyethylene/graphene composite with high exfoliation and high mechanical performance via solid-state shear milling

Due to the high specific area and hydrophobic nature of graphene, it is extremely difficult to fabricate graphene polymer composites without the re-stacking and re-aggregation of graphene sheets, especially when the matrix is a nonpolar polymer, such as high-density polyethylene (HDPE). Applying the solid-state shear milling (S3M) technique in preparation of a graphene/HDPE composite, we successfully solved the problems mentioned above. Highly dispersible exfoliated superfine HDPE/graphene compounding powder was prepared by the S3M technique in the solid state. HDPE/graphene composites with high dispersion and high mechanical performance were subsequently prepared via melt-based processing using this compounding powder. Transmission electron microscopy, scanning electron microscopy and wide-angle X-ray diffraction revealed that the graphene sheets exfoliated into individual sheets inside the polymer matrix. Fourier-transform infrared spectroscopy confirmed that new chemical bonds were generated between graphene and HDPE chains after the S3M process. Thermal analysis indicated that the interaction between HDPE and graphene was strengthened. The advanced material presents significant increases in yield strength, impact strength and elongation at break compared to conventional melt blending composites and neat HDPE. Tough and strong HDPE/graphene composites are suitable for a wide range of applications. Because of this method's solid-state melting-based processing, which does not require solvent, this approach possesses great potential for large-scale application in industry.