Beneficial influence of MWCNT on the pyridine-imine catalyzed ethylene polymerization: effect of type, content and technique

A series of low-density polyethylene (LDPE)/nano-composites containing different content and type of MWCNTs were prepared by in-situ polymerization and solventevaporation techniques, and analyzed by differential scanning calorimeter, FT-IR, SEM and TGA to investigate the thermal, structural, morphological and thermal stability of the resultant nano-composites compared to the sample obtained by 50:50 molar ratio of Ni: Fe catalysts combination at the same condition in presence of MWCNT. Overall activity of these catalysts reduced (from 7.50 × 104 to at least 0.66 × 104 g of PE. mol (Fe+Ni)-1. hr-1). The produced LDPE/nano-composites were showed the lowest melting point as well as crystallinity in presence of MWCNT (30- 50 nm). Whereas, the resultant sample in presence of MWCNT (20-30 nm) exhibited the lower vinyl content (0.12) than the neat polyethylene blend. Based on this analysis, the branch extent varied from 11.55 to 70.81 CH3 branch per 1000 carbon atoms. The sample prepared by 10.50% of MWCNT (30-50 nm) were exhibited the highest onset and endset degradation temperature (217.74 and 708.71 oC, respectively). However, addition 2.33% of MWCNT (20-30 nm) improved the overall thermal stability of the neat polyethylene blend up to 400 oC. Almost, an irregular shape of morphologies was seen for the obtained samples. The samples prepared by in-situ polymerization were shown distinct shape of morphology as well as two peak of melting point in SEM images and DSC traces, respectively