Modification Of Carbon Nanomaterials And Compounding With Polyethylene

As carbon nanomaterials with many excellent properties,carbon nanotubes(MWCNTs)and graphene are greatly limited in industrial application due to their strong van der Waals force.At present,the most common method is to carry out covalent modification,but it is costly,not easy to industrialize and not environmentally friendly.So it has not been able to achieve large-scale application.Modification of MWCNTs by noncovalent is a promising approach.This paper has studied from the following three aspects:(1)Conductive composites were prepared by two-dimensional CGNPs and one-dimensional MWCNTs filled PE.The formation of conductive networks of two-dimensional or one-dimensional carbon nanomaterial composite systems and their effects on mechanical and electrical properties were studied.The results show that the loading of CGNPs is 8 wt%when the antistatic of CGNPs/PE composites is achieved,and the elongation at break of pure PE is increased more than doubled.The antistatic loading of MWCNTs/PE is 1 wt%,and the elongation at break of composites has dropped.Moreover,the rheological test shows that there is a certain correlation between the rheological percolation threshold and the conductive percolation threshold.It is found that MWCNTs have higher conductivity and efficiency,and CGNPs can maintain better mechanical properties after filling PE.(2)A simple and effective method,modifying MWCNTs with cationic waterborne epoxy emulsion,was developed to improve the dispersion of multi-walled carbon nanotubes(MWCNTs)and enhance the interfacial interaction between matrix and the filler.The dispersion of epMWCNTs in polymer was characterized by Scanning Electron Microscope and Transmission Electron Microscope.Rheological analysis revealed that filling lower concentration epMWCNTs can form a conductive network structure in the PE matrix,obtaining a lower percolation threshold and lower volume resistivity,compared with unmodified MWCNTs(pMWCNTs).In addition,the nanocomposites have more excellent mechanical properties.(3)The ionic-gemini surfactant 4,4’-di(tetradecyl)diphenylmethane disulfonate(DSDM)and cationic surfactant cetyltrimethylammonium bromide(CTAB)were sequentially subjected to MWCNTs(sMWCNTs)by π-π interaction and electrostatic adsorption,and then filled with polyethylene(PE).After modified,the interface modulus of MWCNTs and PE was improved by nanoindenter test.Combined with scanning electron microscopy and rheological tests,it was found that this can effectively promote the dispersion of MWCNTs and the formation of conductive network.This gives the sMWCNTs/PE composite a lower conductive percolation threshold and good ductility.