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 (X₁), monomer pressure (X₂), and [Al]/[Ti] molar ratio (X₃) 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 × 10⁶ 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.

Keywords:

• Graphene
• Morphology
• Polymerization
• Response surface methodology (RSM)
• UHMWPE
• Ziegler-Natta