Chemical modification of multiwalled carbon nanotubes by polyethylene-grafted maleic anhydride

Multiwalled carbon nanotubes (MWCNTs) were oxidized by an acid mixture (concentrated H₂SO₄∶HNO₃ =3∶1v/v) to form carboxyl groups, which were then reacted with anhydride ethylene diamine by an amidation reaction to introduce amine end groups that were subsequently grafted to polyethylene/maleic anhydride copolymer (PE-g-MA) to increase the dispersion of the modified MWCNTs in a polyethylene (PE) matrix. The chemical modification of the MWCNTs was verified by FTIR, XPS and Raman spectroscopy. The modified MWCNT/PE composites exhibited an electrical percolation threshold at 0.67 vol% MWCNTs. The volume resistivities of the modified MWCNT/PE composites decreased from 10¹6 to 10⁵Ω · m with increasing MWCNT content from 0.1 to 1.2 vol%