Synthesis of polypropylene/clay nanocomposites using bisupported Ziegler‐Natta catalyst

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. V C 2012 Wiley Periodicals, Inc. J Appl Polym Sci 125: E453-E461, 2012

“…The catalyst preparation was carried out according to our previous studies with some modifications 10–13. To dry the MWCNTs, they were heated for 2 h at 200°C in vacuo .…”

Section: Methodsmentioning

confidence: 99%

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

Amoli

Ramazani

Izadi³

2012

“…Among the new methods, progress of Ziegler-Natta catalysts, optimization of the synthesis processes and usage of the reinforcing agents in the polymer matrix could enhance all on-demand properties of the synthesized polymer. 12 In recent years, many attempts have been conducted to fabricate nanocomposites based on various types of PE such as UHMWPE containing different nanostructures such as carbon nanotube, 19,20 nanoclay, [21][22][23] SiO 2 , 24-28 graphene, 29,30 graphene oxide (GO), 31,32 and molybdenum disulfide. [33][34][35] Nevertheless, a challenging task for this field is fabrication of UHMWPE nanocomposites with uniformly dispersed fillers.…”

Section: Introductionmentioning

confidence: 99%

SiO₂‐covered graphene oxide nanohybrids for in situ preparation of UHMWPE/GO(SiO₂) nanocomposites with superior mechanical and tribological properties

Haddadi

Ramazani

Kheradmand

et al. 2019

The modified Hummer technique was used in the preparation of graphene oxide (GO) nanosheets, and then SiO2 decorated GO [GO(SiO2)] nanosheets were synthesized via the sol–gel method. Then, ultrahigh‐molecular‐weight polyethylene (UHMWPE) nanocomposites loaded with 0.5, 1, 1.5, and 2 wt % of GO(SiO2) were prepared using magnesium ethoxide/GO(SiO2)‐supported Ziegler–Natta catalysts via the in situ polymerization. Morphological study of the prepared polymer powders was assessed using field‐emission scanning electron microscopy, which showed that GO(SiO2) nanohybrids have been uniformly dispersed and distributed into the UHMWPE matrix. Also, the neat UHMWPE and its nanocomposites were evaluated with different analyses, including viscosity‐average molecular weight measurement, differential scanning calorimetry, thermogravimetric analysis, tensile test, scratch hardness, and pin‐on‐disk test. The characterization of the UHMWPE nanocomposites indicated that many characterizations, including the mechanical, thermal, and tribological properties of UHMWPE, were significantly improved by incorporation of these new nanosheets in spite of the molecular weight reduction of the polymeric matrix and the improved flowability and processability of the produced nanocomposite. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47796.

“…Also, this might have been due to the fact that the concentration of reactive sites on the particle surface was not great enough or was not uniform. It is worthwhile to point out that several parameters, such as the polymerization time, reaction temperature, pressure, and Al/Ti molar ratio, could influence the polymerization rate . In addition, the reactivity of monomer strongly depended on its size.…”

Section: Resultsmentioning

confidence: 99%

Novel fabrication route for porous silicon carbide ceramics through the combination of in situ polymerization and reaction bonding techniques

Ebrahimpour

Esmaeili

Griffon

et al. 2014

For the first time, an in situ polymerization technique was applied to produce mullite-bonded porous SiC ceramics via a reaction bonding technique. In this study, SiC microsized particles and alumina nanopowders were successfully coated by polyethylene (PE), which was synthesized from the particle surface in a slurry phase reactor with a Ziegler-Natta catalyst system. The thermal studies of the resulting samples were performed with differential scanning calorimetry and thermogravimetric analysis. The morphology analysis obtained by transmission electron microscopy and scanning electron microscopy (SEM) confirmed that PE was successfully grafted onto the particle surface. Furthermore, the obtained porous ceramics were characterized in terms of their morphologies, phase composition, open porosity, pore size distribution, and mechanical strength. SEM observations and mercury porosimtery analysis revealed that the quality of the dispersion of nanosized alumina powder into the microsized SiC particles was strongly enhanced when the particles were coated by polymers with in situ polymerization. This resulted in a higher strength and porosity of the formed ceramic porous materials with respect to the traditional process. In addition, the X-ray diffraction results reveal that the amount of mullite as the binder increased significantly for the samples fabricated by this novel method. The effects of the sintering temperature, forming pressure, and polymer content on the physical and mechanical properties of the final porous ceramic were also evaluated in this study.