Achieving an efficient catalyst in the ATRP system with a simple design, preparation from available materials, and high recyclability is a significant challenging issue. To attain the goal, herein, we used chitosan (CS)-modified cellulose filter paper (FP) as a green support for the synthesis of dip catalyst. The preparation of this catalyst involved surface treatment of the FP strips by CS coating through a dipping method, which increased the affinity of the substrate for adsorbing copper ions in the next step. The Cu@CS-FP catalyst was prepared without the requirement of any ligands. The synthesized dip-catalyst, in the form of the strips, was employed for the first time in the ATRP reaction of methyl methacrylate to assay catalytic activity. Catalytic insertion/ removal (ON/OFF) experiments were carried out during the polymerization. A reasonable control over the molecular weight with high conversion (68%) and polydispersity index of 1.32 under mild reaction conditions were obtained. Significantly, because of the facile separation of the catalyst, the amount of copper that remained in the polymer was very low (2.7 ppm). Also, the recyclability of the catalyst was investigated for five runs. The conversion in the final run was 64% without a loss of catalyst efficiency.
In this investigation, the shockwave propagation caused by the explosive detonation in a complex environment has been studied by the open-source Computational Fluid Dynamics (CFD) package, OpenFOAM ® . An extended solver was developed to take the effect of explosion energy into account. The Becker-Kistiakowsky-Wilson (BKW) equation of state (EOS) was implemented in OpenFOAM ® to calculate the detonation impact on the surrounding fluid density variations. Also, the influence of two turbulence modeling approaches of Reynolds-averaged Navier-Stokes (RANS) and Large-eddy Simulation (LES) on the prediction of explosion pressure was studied and compared against previous experimental and numerical studies. The comparisons demonstrated the accuracy of the implemented BKW EOS in calculating the fluid density. Further, it was shown that the LES approach is capable of capturing the unsteady nature of detonation in the near-field of the explosive. Examining the instantaneous velocity vectors of the LES results revealed sequential wave fronts that were responsible for rapid changes in the pressure signals. Furthermore, ground pressure contours demonstrated that the shock waves spread on the ground in a circular shape. The results of the current study suggested that the OpenFOAM ® technology is powerful to incorporate various physical models, including the equation of state and scale-resolving methods such as LES, to capture the complex nature of the detonation phenomenon.
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