Optimization of UHMWPE/Graphene Nanocomposite Processing using Ziegler-Natta Catalytic System via Response Surface Methodology

Abstract

Optimization of operational conditions for the preparation of Ultrahigh-molecular-weight polyethylene (UHMWPE)/Graphene nanocomposites with Ziegler-Natta catalyst was carried out via response surface methodology (RSM). This study deals with the optimization of process variables to optimize the productivity and molecular weight. A three-factor, three-level Box-Behnken design with temperature (X 1 ), monomer pressure (X 2 ), and [Al]/[Ti] molar ratio (X 3 ) as the independent variables were selected for the study. The dependent variables were productivity and molecular weights of the final nanocomposites. It was developed by using the three parameters at three levels including 50, 60, and 70 C for temperature; 4, 6, and 8 bar for pressure; and 176, 318, and 460 for [Al]/[Ti] molar ratios. The optimum reaction conditions derived via RSM were: temperature 60 C, pressure 8 bar, and [Al]/[Ti] molar ratio 242. Productivity and molecular weight were 2107 g PE/mmol Ti.h and 3.7 Â 10 6 g/mol, respectively, under optimum conditions. Morphological information was determined by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Obtained results show that graphene layers in these nanocomposites were completely exfoliated and dispersed uniformly in the polyethylene matrix while no nanoparticle cluster was formed.

Highly efficient FeCl3 doped Mg(OEt)2/TiCl4-based Ziegler–Natta catalysts for ethylene polymerization

“…[4,5] Nowadays, as two kinds of major industrial materials of the carrier, MgCl 2 ·nROH and magnesium ethoxide, Mg(OEt) 2 , are widely known. [6,7] Although, Mg(OEt) 2 has a morphological subject regarding roundness and particle size distribution as compared with MgCl 2 ·nROH, the catalyst made by Mg(OEt) 2 shows a higher activity. [8,9] Industrial catalysts precursors containing magnesium compounds such as MgCl 2 or Mg(OEt) 2 in conjunction with TiCl 3 or TiCl 4 showed great performance in olefin polymerization; however, still there are lots of modifications of ZN catalysts varying in the way of preparation of the support [10][11][12][13][14] and differences in the active component compound structure and the presence of various modifying additives.…”

“…[15][16][17][18] Lately, investigations have shown that doping a suitable amount of Lewis acids in MgCl 2 or Mg(OEt) 2 supports would be an effective way to improve their catalytic performance in α-olefin polymerization. The mostly used doping agents were based on different metal halides such as MnCl 2 , [2] ZnCl 2 , [3] NaCl, [4] AlCl 3 [5,6,19], and the mixture of metal halide with metalloids like ZnCl 2 -SiCl 4 system. [7,8] These agents not only can have notable effect on catalyst activity but also have the ability to change catalyst efficiency toward higher α-olefins in LLDPE production as well as stereo-regularity of final polymer in propylene polymerization.…”

Molecular dynamics simulation of α‐ZrP/UHMWPE blend composites containing compatibilizer and its tribological behavior under seawater lubrication

“…3 Ultra-high molecular weight polyethylene (UHMWPE) has good self-lubricity, chemical inertness, and mechanical properties. [4][5]6 Because of its non-toxic properties and deficient water absorption, UHMWPE is considered a potential friction pair material for marine engineering equipment. 7,8 However, the highwear rate of UHMWPE limits its application as a friction pair material.…”

Effects of monomer length on α‐olefins polymerization using a conventional Ziegler–Natta catalyst

“…Because of their wide applications, during the recent years, more researches have been devoted to the synthesis and understanding of the properties of polyα‐olefins . In Galland et al study about the effects of monomer size on polymerization behavior from poly1‐hexene to poly1‐octadecene, the results showed that steric hindrance has the predominant effect on the catalyst activity at 0°C.…”