Mechanical reinforcement of polyethylene using n-alkyl group-functionalized multiwalled carbon nanotubes: Effect of alkyl group carbon chain length and density



Polyethylene (PE) is one of the most produced synthetic resins in the world. Functionalized multiwalled carbon nanotube (MWCNT) is a potential nanoscale filler to realize the next generation strong and multifunctional PE composites. We demonstrate that MWCNTs grafted with short n-alkyl groups are effective nanofillers for mechanical reinforcement of PE composites. At 1 wt% filler loading, the yield stress and Young's modulus improve significantly up to 54 and 63% compared with neat PE, respectively. Among ductile properties, tensile strength increases up to 30%; ultimate strain is preserved; and toughness increases up to 33%. More important, we show that short n-alkyl groups can be grafted on MWCNTs much easier than long chain polymers. Further, we find that alkyl groups of C14–C18 chains have the optimum length for reinforcement. The optimum density of grafted alkyl groups is around 0.390–0.423 μmol/mg when the C14 alkyl groups are used. Overall, the results manifest that MWCNTs grafted with n-alkyl groups with suitable length and density are efficient nanoscale fillers for high-performance PE composites. POLYM. ENG. SCI., 54:336–344, 2014. © 2013 Society of Plastics Engineers