Bi-supported Ziegler–Natta TiCl4/MCM-41/MgCl2 (ethoxide type) catalyst preparation and comprehensive investigations of produced polyethylene characteristics

Bi-supported Ziegler–Natta catalysts (TiCl₄/MCM-41/MgCl₂ (ethoxide type)) were synthesized to improve the morphology and the properties of polyethylene. The morphology control is a crucial issue in polymerization process, while tailoring the properties of polymers is needed for specific applications. The catalysts were synthesized in different ratios of two supports with impregnation method. The polymerization process was carried out in atmospheric slurry reactor. The catalysts were characterized with scanning electron microscopy - energy dispersive X-ray spectroscopy (SEM–EDX), inductively coupled plasma, Fourier transform infrared spectrometry (FTIR), and Brunauer-Emmett-Teller (BET) methods. The polymers were analyzed with scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry, FTIR, and tensile-strength analyses. Ubbelohde viscometer and frequency sweep measurements showed that the synthesized polymers are ultra-high-molecular-weight polyethylene. Mechanical properties of polymers showed higher Young's modulus in samples containing MCM-41, having higher thermal stability supported by TGA analysis. SEM images of bi-supported catalyst showed a controlled spherical morphology with uniform size distribution. SEM analysis support that the polymers replicate their morphology from catalyst, improving their morphology comparing to MgCl₂-supported catalyst. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48553.     

Effects of Neutron Irradiation on the Current–Voltage Characteristics of SiO<Subscript>2</Subscript> Nanoparticles

Current–voltage characteristics of SiO₂ nanoparticles have been studied before and after neutron irradiation within 5 V steps in the voltage range of ??100 V to +?100 V at room temperature (RT). The angle of the current–voltage curve is changed appropriately for neutron irradiation periods. Simultaneously, it is seen that the amount of the current flowing through the environment increases proportionally to the irradiation period. Moreover, the mechanism of electrical conductivity appropriate to the obtained results is given in this work.     

Effect of Neutron Flux on the Frequency Dependence of Permittivity of Nano Silicon Particles

In the present work, nano silicon is irradiated with a neutron flux (2x10 ¹³ n ?cm ^?2 s ^?1) up to 20 hours at different times. In the first stage frequency dependencies of real and imaginary parts of the permittivity of nanomaterials affected by neutron flux was analysed comparatively. As a result of this analysis it is known that the permittivity of nano silicon increases under the influence of neutron flux. The dependence of real and imaginary parts of permittivity of nano silicon particles is also reviewed. Moreover, the mechanism of the observed peaks and other effects is given in the work.     

In Situ Synthesis of Ultrahigh Molecular Weight Polyethylene/Graphene Oxide Nanocomposite Using the Immobilized Single-site Catalyst

We address the immobilization of single-site catalyst on the graphite oxide (GO) surface using methylaluminoxane. Ethylene polymerization was performed using the immobilized catalyst and the nanocomposite of ultrahigh molecular weight polyethylene (UHMWPE)/GO with less entanglement density was obtained. It was observed that the drawability, mechanical and thermal properties of the produced polymer significantly are affected by the anchoring of polymer chains to the GO nanosheets. The orientation and location of crystalline lamellae and nanosheets were verified by microscopic techniques. Besides, X-ray analysis demonstrated the dispersion of GO within the UHMWPE phase and crystallinity of UHMWPE/GO nanocomposites enhanced during drawing process.     

Effects of Neutron Flux on the Temperature Dependency of Permittivity of 3C-SiC Nanoparticles

In the present work, the real and imaginary parts of permittivity of cubic modification silicon carbide (3C-SiC) nanoparticles are investigated before and after neutron irradiation. The real and imaginary parts of permittivity for the samples were studied in 0.1 Hz–2.5 MHz frequency and 100 K–400 K temperature ranges. The samples were continuously irradiated by neutron flux (2x10 ¹³ n ?cm ^?2 s ^?1) up to 20 hours. The real and imaginary parts of permittivity were comparatively studied before and after irradiation. Neutron irradiation effects were studied with comparative analysis of non-irradiated samples. The increase in polarization was observed as a result of the increase in the impact period of neutron flux. All the mechanisms of the observed effects are given in the work.     

Novel polymeric nanogel as diversion agent for enhanced oil recovery

The authors discuss the nanogel application as deep diversion agent for enhanced oil recovery (EOR). Experimental studies of nanogel show that its utilization allows combining the advantages of gels used in bulk and sequential injection. Addition of light metal nanoparticles subsequently increases the gel system strength while crosslinking, however it has no impact on flow ability of polymer solution. The nanogels application as deep diversion agent for EOR was studied in treatment experiments at two crossflow layered artificial cores. Nanoparticle addition increases residual resistance factor of polymer gel up to 22% and show a more long-lasting effect. Oil recovery increase for nanogel application was 6% original oil in place (OOIP) in comparison with gel without nanoparticles. It has been shown the gel bank's position impact on oil recovery efficiency at in situ fluid diversion operations. The series of experiments for both types of gels with three different gel blank positions were conducted. Experimental results showed the best value of 19% and 28% OOIP recovery increase in near production line position for gel and nanogels, respectively.     

Selection methodology for screening evaluation of EOR methods

The choice of enhanced oil recovery (EOR) methods for specific reservoir conditions is one of the most difficult tasks for a reservoir engineer. Taber (Taber, 1980 Taber, J. J. (1980). Research on enhanced oil recovery: past, present and future. Pure Appl. Chem., 52:1323–1347.[Crossref], [Web of Science ®] , [Google Scholar]; Taber et al., 1997a,b Taber, J. J., Martin, F. D., and Seright, R. S. (1997a). EOR screening criteria revisited. Part 1: Introduction to screening criteria and enhanced recovery field projects. SPE-35385-PA. Taber, J. J., Martin, F. D., and Seright, R. S. (1997b). EOR screening criteria revisited. Part 2: Applications and impact of oil prices. SPE-39234-PA. ) gave informative overview of EOR research history. He also offered technical screening guides for EOR nowadays known as Taber's tables. It should be noted that the approach recommended by Taber could not be taken as strong mathematical ranking of EOR methods. The authors propose an approach for EOR methods selection, based on fuzzy logic, possibility theory, and Bayesian inference mechanisms. Rankings were made by way of best EOR method selection for every criteria using fuzzy intervals comparison. Final correction of each EOR selection coefficient was performed by the generalized Bayesian inference mechanism. Application of this methodology for reservoir conditions of Alberta oil field, as well as the offshore field “Guneshli,” allowed for choosing the most effective EOR method, confirming the accuracy and feasibility of the proposed approach. Simple calculation (not more than five iterations) allows the automation of the process of selecting the most effective EOR method for a particular field.     

Neutron Irradiation Effects on the Temperature Dependencies of Electrical Conductivity of Silicon Carbide (3C-SiC) Nanoparticles

Silicon - The effects of the temperature and neutron irradiation on the electrical conductivity of nanocrystalline silicon carbide (3C-SiC) was investigated at different frequency regions....