Preparation of ultrahigh-molecular-weight polyethylene/carbon nanotube nanocomposites with a Ziegler-Natta catalytic system and investigation of their thermal and mechanical properties

Amoli, B. M ; Sharif University of Technology | 2012

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  1. Type of Document: Article
  2. DOI: 10.1002/app.36368
  3. Publisher: Wiley , 2012
  4. Abstract:
  5. In this research, ultrahigh-molecular-weight polyethylene (UHMWPE)/multiwalled carbon nanotube (MWCNT) nanocomposites with different nanotube concentrations (0.5, 1.5, 2.5, and 3.5 wt %) were prepared via in situ polymerization with a novel, bisupported Ziegler-Natta catalytic system. Magnesium ethoxide [Mg(OEt) 2] and surface-functionalized MWCNTs were used as the support of the catalyst. Titanium tetrachloride (TiCl 4) accompanied by triethylaluminum constituted the Ziegler-Natta catalytic system. Preparation of the catalyst and the polymerization were carried out in the slurry phase under an argon atmosphere. Support of the catalyst on the MWCNTs was investigated with Fourier transform infrared spectroscopy. The results confirmed the interaction between the catalyst and the MWCNT hydroxyl groups. Intrinsic viscosity measurements showed an ultrahigh molecular weight in the produced samples. Scanning electron microscopy images confirmed the good dispersion of MWCNTs throughout the polyethylene (PE) matrix. The crystallization behavior of the samples was examined with differential scanning calorimetry. Its results showed that the crystal content of the samples increased with increasing MWCNT concentration up to 1.5 wt %. The same trend was observed for the crystallization temperature, whereas the melting temperature did not change with increasing MWCNT concentration up to 1.5 wt %, but it decreased beyond this concentration. In addition, thermogravimetric analysis results showed that the addition of MWCNTs noticeably improved all of the investigated thermal stability factors of the UHMWPE/MWCNT nanocomposites compared to those of pure PE. The results obtained from tensile testing revealed significant increases in the Young's modulus, yield stress, and ultimate tensile strength. This indicated a tremendous improvement in the mechanical properties of the PE/MWCNT nanocomposites compared to those of pure PE
  6. Keywords:
  7. Polyethylene (PE) ; Argon atmospheres ; Catalytic system ; Crystal content ; Crystallization behavior ; Crystallization temperature ; Ethoxides ; Hydroxyl groups ; In-situ polymerization ; Nanotube concentration ; Scanning electron microscopy image ; Slurry phase ; Thermal and mechanical properties ; Thermogravimetric analysis (TGA) ; Titanium tetrachlorides ; Triethylaluminum ; Ultimate tensile strength ; Ultra-high molecular weight ; Young's Modulus ; Ziegler natta polymerization ; Ziegler-Natta ; Carbon nanotubes ; Differential scanning calorimetry ; Fourier transform infrared spectroscopy ; Magnesium ; Mechanical properties ; Multiwalled carbon nanotubes (MWCN) ; Nanocomposites ; Polyethylenes ; Polymerization ; Scanning electron microscopy ; Tensile testing ; Thermogravimetric analysis ; Thermoplastics ; Titanium ; Viscosity measurement ; Catalyst supports
  8. Source: Journal of Applied Polymer Science ; Volume 125, Issue SUPPL. 1 , 2012 , Pages E453-E461 ; 00218995 (ISSN)
  9. URL: http://onlinelibrary.wiley.com/doi/10.1002/app.36368/abstract