Synthesizing ethylene/1-octene copolymer and its nanocomposites with graphene and carbon nanotubes using a Ziegler − Natta catalyst

Abstract

Copolymerization of ethylene and 1-octene was carried out using a Ziegler-Natta catalyst and the optimization of copolymerization conditions was studied. The optimum polymerization activity was obtained at 60 °C and [Al]:[Ti] molar ratio of 143:1. It was observed that the increase in the comonomer ratio in the feedstock influenced the physical properties of the final copolymer obtained. The results showed a range of crystallinity (Xc) from 68.5% to 34.8% and a range of melting temperature (Tm) from 140 °C to 129 °C for the synthesized copolymers. The viscosity average molecular weight (M̅v) of the polymers decreased as the polymerization temperature increased, however, by increasing the monomer pressure, the M̅v of the polymers and the catalyst activity increased. Polymer nanocomposites containing graphene and multi-walled carbon nanotubes with different particle sizes were prepared under the optimum copolymerization conditions. The addition of graphene and multi-walled carbon nanotubes decreased the activity of the catalyst. However, the thermal stability, and crystallinity of the polymers were found to be increased.