Study On Mechanical,electrical And Rheological Properties Of Hybrid GNP/MWCNT Filled HDPE Composites

Polymer composites have become the popular topics of polymer research fields because of their excellent mechanical properties and functionality.Carbon fillers are good fillers to improve the performance of polymer materials and broaden their applications.High-density polyethylene(HDPE)is inexpensive and has good processability.The addition of carbon fillers can not only enhance tougheness and strength of HDPE matrix,but also endow its good electrical conductivity.In this project,HDPE,carbon fillers graphene nanoplatelets(GNP),GNP/multi-walled carbon nanotube(MWCNT)hybrid fillers,and compatibilizers(POE-g-MA,HDPE-g-MA)were melt blended to achieve HDPE composites.The effect of the type and content of the fillers and compatibilizers on the rheological behavior,electrical conductivity and mechanical properties of the composites had been investigated.The main research results are as follows:(1)The effect of GNP and POE-g-MA content on the rheological properties,electrical and mechanical properties of HDPE/GNP composites were investigated.The G'curves of HDPE/GNP and HDPE/POE-g-MA/GNP composites showed“second plateau”in the low frequency regions,exhibiting a clear gelation transition.The GNP content at the gel point was 11.50 wt%and 4.00 wt%,respectively.Both composites showed obvious conductive percolation,and the gel point of HDPE/GNP composites was located in the conductive percolation area.The addition of POE-g-MA could significantly improve the toughness of HDPE/GNP composites.When the POE-g-MA content was 20 wt%,the notched Izod impact strength of HDPE/POE-g-MA/GNP composites at the gel point showed the maximum of 49.50 k J/m~2,which was about 7.62times higher than that of neat HDPE,indicating that the mechanical properties of this composites had some correlations with the rheological behavior.(2)The effect of the ratio and content of GNP/MWCNT hybrid fillers on the rheological properties,electrical and mechanical properties of HDPE/GNP/MWCNT composites was investigated.When the GNP/MWCNT hybrid filler ratio was 7/3,5/5,and 2/8,the gel point of the three HDPE/GNP/MWCNT composites appeared at GNP/MWCNT content of 3.00 wt%,2.45 wt%,1.42 wt%,and the gel points were located in the conductive percolation zone.When the GNP/MWCNT content was 0.5wt%,the notched Izod impact strength of three HDPE/GNP/MWCNT composites was15.05 k J/m~2,9.98 k J/m~2,and 10.42 k J/m~2,which was about 2.32,1.54,and 1.60 times as high as that of the pure HDPE.(3)The effect of compatibilizer types on the rheological behavior,electrical and mechanical properties of HDPE/GNP/MWCNT composites was investigated.When the GNP/MWCNT ratio was 7/3,the gel point of HDPE/GNP/MWCNT,HDPE/HDPE-g-MA/GNP/MWCNT,HDPE/POE-g-MA/GNP/MWCNT composites were 3.00 wt%,4.64 wt%,and 2.10 wt%,respectively;When the GNP/MWCNT ratio was 2/8,three composites had gel points at GNP/MWCNT contents of 1.42 wt%,2.50 wt%,and 1.25wt%,respectively.With the addition of compatibilizers,the composites conductive percolation area became wide and shifted to the high GNP/MWCNT content.When the GNP/MWCNT content was 0.5 wt%and the GNP/MWCNT ratio was 7/3,the notched Izod impact strength of the HDPE/POE-g-MA/GNP/MWCNT composites was 20.17k J/m~2,which was about 3.10 times higher than that of neat HDPE.When the GNP/MWCNT ratio was 2/8,the notched Izod impact strength of the composites attained 53.5 k J/m~2,which was about 8.23 times as high as that of neat HDPE.(4)The composites at the gel points exhibit network structure.The addition of GNP/MWCNT hybrid fillers and POE-g-MA can enhance greatly the toughness of HDPE/POE-g-MA/GNP/MWCNT composites.When the samples were impacted,more energy can be absorbed and dissipated through the destruction of network,deformation of elastomer,bending deformation and pullout of MWCNT and GNP,the shear bands of HDPE matrix induced by the synergistic effect of MWCNT/GNP hybrid fillers.