Synthesis Of Polyethylene Research Articles

Flexible Monoarylmethyl Substituents in an Efficient Synthesis of Hyperbranched Polyethylene and Polar-Functionalized Polyethylene

Flexible Monoarylmethyl Substituents in an Efficient Synthesis of Hyperbranched Polyethylene and Polar-Functionalized Polyethylene

Stable Ultrahighly Branched Polyethylene Synthesis via Externally Robust Chain-Walking Polymerization

Stable Ultrahighly Branched Polyethylene Synthesis via Externally Robust Chain-Walking Polymerization

Recent Advancements in the Synthesis of Ultra-High Molecular Weight Polyethylene via Late Transition Metal Catalysts.

Ultra-high molecular weight polyethylenes (UHMWPEs) are significant engineering plastics for their unique properties, such as high impact resistance, abrasion resistance, weatherability, lubricity, and chemical resistance. Consequently, developing a suitable catalyst is vital in facilitating the preparation of UHMWPE. The late transition metal catalysts have emerged as effective catalysts in producing UHMWPE due to their availability, enhanced tolerance to heteroatom groups, active polymerization characteristics, and good copolymerization ability with polar monomers. In this review, we mainly focus on the late transition metal catalysts, summarizing advancements in their application over the past decade. Four key metals (Ni, Pd, Fe, Co) for generating linear or branched UHMWPE will be primarily explored in this manuscript.

Recent Advances in Nickel Catalysts with Industrial Exploitability for Copolymerization of Ethylene with Polar Monomers.

The direct copolymerization of ethylene with polar monomers to produce functional polyolefins continues to be highly appealing due to its simple operation process and controllable product microstructure. Low-cost nickel catalysts have been extensively utilized in academia for the synthesis of polar polyethylenes. However, the development of high-temperature copolymerization catalysts suitable for industrial production conditions remains a significant challenge. Classified by the resultant copolymers, this review provides a comprehensive summary of the research progress in nickel complex catalyzed ethylene-polar monomer copolymerization at elevated temperatures in the past five years. The polymerization results of ethylene-methyl acrylate copolymers, ethylene-tert-butyl acrylate copolymers, ethylene-other fundamental polar monomer copolymers, and ethylene-special polar monomer copolymers are thoroughly summarized. The involved nickel catalysts include the phosphine-phenolate type, bisphosphine-monoxide type, phosphine-carbonyl type, phosphine-benzenamine type, and the phosphine-enolate type. The effective modulation of catalytic activity, molecular weight, molecular weight distribution, melting point, and polar monomer incorporation ratio by these catalysts is concluded and discussed. It reveals that the optimization of the catalyst system is mainly achieved through the methods of catalyst structure rational design, extra additive introduction, and single-site catalyst heterogenization. As a result, some outstanding catalysts are capable of producing polar polyethylenes that closely resemble commercial products. To achieve industrialization, it is essential to further emphasize the fundamental science of high-temperature copolymerization systems and the application performance of resultant polar polyethylenes.

Synthesis of Degradable Polyethylene and Poly(ethylene-co-vinyl acetate) by Radical Co- and Terpolymerization of Ethylene, ε-Thionocaprolactone, and Vinyl Acetate

Synthesis of Degradable Polyethylene and Poly(ethylene-<i>co</i>-vinyl acetate) by Radical Co- and Terpolymerization of Ethylene, ε-Thionocaprolactone, and Vinyl Acetate

Synthesis and characterization of waste polyethylene/Bi2O3 composites reinforced with CuO/ZnO nanoparticles as sustainable radiation shielding materials

AbstractIn the present research, waste polyethylene (WPE)/Bi2O3 composites have been investigated as lightweight, inexpensive, and nontoxic lead‐free γ‐ray shielding materials. Different WPE‐based composites were prepared with varying concentrations of Bi2O3 (30 and 40 phr). The effect of adding ZnO and CuO nanoparticles (NPs) inside the WPE/Bi2O3 (30) matrix was studied by incorporating 10 phr of NPs inside it. The nanocomposites' structural, thermal, and mechanical properties and competence in shielding against γ‐radiation are studied. The outcomes revealed that the mechanical properties of the pristine WPE were enhanced after incorporating Bi2O3 by 30 phr, and then it worsened after increasing the Bi2O3 ratio to 40 phr. In contrast, better mechanical properties were obtained for those composites with NPs, where the maximum tensile strength (16.2 MPa) was recorded for the WPE/Bi2O3/CuO composite (higher than WPE by 47.27%). Numbers of parameters like μm, HVL (half‐value layer), TVL (tenth value layer), RPE%, and percentage of heaviness can denote the efficiency of shielding properties of composites at 662 KeV from 137Cs point source. It was found that μm and RPE% reach the maximum value for WPE/Bi2O3 (40 phr). Adding NPs decreases μm of WPE/Bi2O3 (30) slightly.Highlights Composites based on waste polyethylene (WPE)/Bi2O3 (30 and 40 phr) were fabricated. Nano CuO and ZnO improved the mechanical properties of WPE/Bi2O3 (30). WPE/Bi2O3 (40) composites show the best shielding characteristics. Nano CuO and ZnO slightly decreased μm of WPE/Bi2O3 (30).

Spherical and porous Cu2O nanocages with Cu2O/Cu(OH)2 Surface: Synthesis and their promising selectivity for catalysing CO2 electroreduction to C2H4

In the production of C2H4, a vital raw material in the synthesis of polyethylene and polyvinyl chloride, Cu2O is a highly promising catalyst with excellent Faradaic efficiency and selectivity. We propose a method involving the partial reduction of Cu(OH)2 to Cu2O by sodium L-ascorbate for the synthesis of spherical and porous Cu2O nanocages (SPNCs) with a surface containing both Cu2O and Cu(OH)2. High-resolution transmission electron microscopy and electron diffraction measurements revealed ∼ 3-nm pores and a (13¯2) high-index facet on the SPNC, respectively. As SPNCs have a porous structure, their specific surface area is greater (31.10 m2 g−1) than that (6.35 m2 g−1) of spherical Cu2O nanocrystals (SNCs) with solid interiors. Furthermore, SPNCs, when applied as electrocatalysts for catalysing the CO2 reduction reaction (CO2RR), demonstrated remarkable mass activities (16.92 mA mg−1 at −1.15 V vs. reversible hydrogen electrode) for C2H4 production, with a Faraday efficiency reaching an impressive 55.3 %. Stability test data showed a consistent CO2RR current density over 6 h, owing to the porous structure and the presence of both Cu(OH)2 and Cu2O on the catalyst surface. Our proposed SPNC catalysts can be employed as effective CO2RR catalysts for producing C2H4, which may help in reducing the present reliance on petrochemical processes.

Thermally stable C2-symmetric α-diimine nickel precatalysts for ethylene polymerization: semicrystalline to amorphous PE with high tensile and elastic properties.

In α-diimine nickel catalyst-mediated ethylene polymerization, adjusting catalytic parameters such as steric and electronic factors, as well as spectator ligands, offers an intriguing approach for tailoring the thermal and physical properties of the resulting products. This study explores two sets of C2-symmetric α-diimine nickel complexes-nickel bromide and nickel chloride-where ortho-steric and electronic substituents, as well as nickel halide, were varied to regulate simultaneously chain walking, chain transfer, and the properties of the polymers produced. These complexes were activated in situ with Et2AlCl, resulting in exceptionally high catalytic activities (in the level of 106-107 g (PE) mol-1 (Ni) h-1) under all reaction conditions. Nickel bromide complexes, with higher ortho-steric hindrance, exhibited superior catalytic activity compared to their less hindered counterparts, whereas the reverse was observed for complexes containing chloride. Increased steric hindrance in both sets of complexes facilitated higher polymer molecular weights and promoted chain walking reactions at lower reaction temperature (40 °C), while the effect became less pronounced at higher temperature (100 °C). However, the electron-withdrawing effect of ortho-substituents hindered the rate of monomer insertion, chain propagation, and chain walking reactions, leading to the synthesis of semi-crystalline polyethylene with an exceptionally high melt temperature of 134.6 °C and a high crystallinity of up to 31.9%. Most importantly, nickel bromide complexes demonstrated significantly higher activity compared to their chloride counterparts, while the latter yielded polymers with higher molecular weights and increased melt temperatures. These high molecular weights, coupled with controlled branching degrees, resulted in polyethylenes with excellent tensile strength (up to 13.9 MPa) and excellent elastic properties (up to 81%), making them suitable for a broad range of applications.

Simple and Sterically Open Nickel Catalyst for Ultrahigh Molecular Weight Polyethylene Synthesis

Simple and Sterically Open Nickel Catalyst for Ultrahigh Molecular Weight Polyethylene Synthesis

External donor modified Mg-Ti based Z-N catalyst system for synthesis of Ultrahigh molecular weight polyethylene

This study reported novel external donors Diethyl 2,2'-(dimethylsilanediyl) diacetate (DSD1), Diethyl 2,2'-(phenyl(methyl) silanediyl) diacetate (DSD2) and Diethyl 2,2'- (diisopropylsilanediyl) diacetate (DSD3) and triethyl borate (TEB) employed with magnesium dichloride supported Ti-based monoester (Mg-Ti-ME) and magnesium dichloride supported Ti-based diester (Mg-Ti-DE) catalyst for synthesis of Ultrahigh molecular weight polyethylene (UHMWPE). Furthermore, the catalyst was tested with different concentrations of chain-terminating agents to understand the effect on molecular weight. The results showed Mg-Ti catalysts using DSD1, DSD2, and DSD3 and TEB external donors had significantly increased molecular weight in the presence of external donors with decreases in catalyst activity, compared to donor-free catalyst systems. In addition, in the presence of chain terminating agent molecular weight decreases significantly with less effect on catalyst activity. The obtained polymer, thermal properties characterized through differential scanning calorimetry (DSC), morphology through a scanning electron microscope (SEM), particle size of resin through a particle size analyzer and molecular weight through viscosity-average molecular weights method.

Synthesis of Polyethylenes with In-Chain Isolated Carbonyls from CO 2 and Ethylene via a Tandem Photoreduction/Polymerization Protocol

Synthesis of Polyethylenes with In-Chain Isolated Carbonyls from CO ₂ and Ethylene via a Tandem Photoreduction/Polymerization Protocol

High-Performance Catalysts Based on Hybrid Salicylaldarylimine Complexes of Titanium(IV) Dichloride for the Synthesis of Ultrahigh Molecular Weight Polyethylene with Unentangled Macromolecules

High-Performance Catalysts Based on Hybrid Salicylaldarylimine Complexes of Titanium(IV) Dichloride for the Synthesis of Ultrahigh Molecular Weight Polyethylene with Unentangled Macromolecules

High-Performance Catalysts Based on Hybrid Salicylaldarylimine Complexes of Titanium(IV) Dichloride for the Synthesis of Ultrahigh Molecular Weight Polyethylene with Unentangled Macromolecules

The features of ethylene polymerization in the presence of dichloridobis(salicylaldaryliminato)titanium(IV) complexes containing a 4-allyloxy-2,3,5,6-tetrafluorophenylimino group, namely, {2‑[(4-CH2=CH-CH2O)C6F4N=CH]-6-R1-4-R2-C6H2O}2TiCl2 (R1 = t-Bu, CMe2(Ph); R2 = H, Me, OMe, t-Bu, CMe2(Ph), Cl, Br) in the presence of methylalumoxane, have been studied. All the complexes exhibit high catalytic activity (27.8×106 гПЭ∙мольTi‐ 1∙МПаC2H4-1∙ч‐ 1)) in the temperature range of 10‒60°C and form powdered ultrahigh molecular weight polyethylene (UHMWPE) (M = (4.4–16.0) × 106 g/mol) with a low number of intermolecular entanglements. It has been shown that during polymerization, the complexes are immobilized on UHMWPE macromolecules.

Synthesis of hyperbranched polyethylene and carboxylate functionalized polyethylene using bis(benzocyclopentyl) α-diimine Pd(II) catalysts with axial substituent-constrained strategy

Preparation of hyperbranched polyethylene and its polar functionalized polyethylene by chain walking polymerization technology is convenient and efficient. In this work, two bis(benzocyclopentyl) α-diimine ligands with different backbones and the corresponding Pd(II) catalysts were designed and synthesized. The axially open palladium catalysts enabled the polymerization of ethylene to afford hyperbranched polyethylene with low molecular weights (2.58–8.21 kg/mol) and high branching densities (111–142/1000C). Moreover, hyperbranched E-MA copolymers with high MA incorporation ratios (up to 20.7 mol%) were obtained by copolymerization of ethylene with MA using these Pd(II) catalysts. In addition, the polyethylene and E-MA copolymers obtained from the catalyst with butyl backbone exhibited significantly higher molecular weights with remarkably higher catalytic activities compared to those obtained from the acenaphthene backbone catalyst. Most interestingly, the axial substituent-constrained strategy of o-aryl bis(benzocyclopentyl) substituents provides a more open axial space, facilitating the insertion of methyl acrylate, and the formation of branching, compared to the conventional chain o-aryl alkyl substitution.

Synthesis, optical, mechanical characteristics, and gamma-ray shielding capacity of polyethylene -basalt mixture

In this work, a new polymeric composite consisting of polyethylene polymers as a base material filled with different weight percentages of basalt rock was prepared. The basalt ratio was added to the base material with percentages of 1.0 up to 20.0 wt%. The crystal structure, optical, mechanical properties, and gamma-ray shielding capacity of the undoped and the doped polymeric samples which were coded as HDPE-Bx, where x = 0.0, 1.0, 3.0, 5.0, 10.0, and 20.0 wt% were investigated. The optical energy band gap (EOptical) of the prepared mixture was decreased by increasing the basalt concentration in the mixture from 4 to 2.6 eV for the allowed direct transition and from 5.5 to 4.7 eV for the allowed indirect transition. The mechanical properties of the HDPE polymers were enhanced with the enhancement of Basalt (powder) added to the host polymers with ratios ranging from 0.0 to 20.0 wt%. Radiation shielding capacity of the prepared samples was investigated in the 0.015–15 MeV photon energy via Phy-X software and MCNP-5 simulation code. Results revealed that the mass attenuation coefficient (μm) of the prepared samples increased with increasing the basalt ratio from 1.0 to 20 wt%. Besides, the half-value layer (HVL) decreased. The μm ranged from 0.7455 to 2.956 cm2/g for HDPE-B0 to HDPE-B20 at 0.015 MeV photon energy, while at 15 MeV, the result refers to an increase in the μm from 0.0181 to 0.0189 cm2/g for HDPE-B0 to HDPE-B20. The HVL of the prepared samples was arranged in the order that HDPE-B0 > HDPE-B1 > HDPE-B3 > HDPE-B5 > HDPE-B10 > HDPE-B20. This order assured that HDPE-B20 is better in shielding applications than the other prepared samples.

Synthesis and characterization of polyethylene

A combined intumescent flame retardant expandable graphite (EG), with an initial expansion temperature of 155°C and expansion volume of 515 mL g-1, was successfully prepared based on a chemical intercalation method of material graphite under oxidation of KMnO4, intercalation of H2SO4 and Na4B2O7· 10H2O at the mass ratio C : KMnO4 : H2SO4 (98%) : Na4B2O7· 10H2O of 1.0 : 0.4 : 5.5 : 0.6 (H2SO4 diluted to a mass concentration of 80-wt. % before reaction), and characterized by expansion volume (EV), initial expansion temperature, X-ray diffraction (XRD). The flame retarding and thermal properties of LLDPE/EG and LLDPE/EG/APP composites (LLDPE-Linear low-density polyethylene; APP-ammonium polyphosphate) were investigated and characterized by limiting oxygen index (LOI), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric (TG) and differential thermal analysis (DTA). The results showed that addition of EG (30-wt. %) increased the LOI of 70LLDPE/30EG composite to 28.4 %. Even more, the synergistic effect of 20% EG together with 10% APP improved the LOI of 70LLDPE/20EG/10APP composite to 30.5%. At the same time, temperatures corresponding to a 1% weight loss and a maximum weight loss rate increased at about 50°C and 2°C, respectively. The 70LLDPE/10APP/20EG composite exhibited higher flame retardancy even at a lower residual char than 70LLDPE/30EG specimen. The intercalated borate was more effectual in improving the flame retardancy than the direct additive of Na4B2O7· 10H2O.

Star polyethylenes by coordinative polymerization

AbstractWith their distinct star architecture, star polymers show some desirable materials properties and have received extensive research interest. To date, the advancements in living anionic and controlled radical polymerization techniques have empowered the versatile synthesis of a variety of star polymers from several groups of monomers that are amenable to these polymerization techniques. Despite the fact that polyethylene is the largest produced commodity polymer worldwide, the synthesis of star polyethylenes as a unique polyethylene grade has somehow lagged due to the limited availability of powerful transition metal catalysts that can effectively facilitate ‘living’ ethylene polymerization for the construction of star architectures. Nevertheless, some progress had been made over the past two decades. In this review, we attempt to summarize the developments in the area, with an emphasis on synthesis strategies.

Flame retardant phosphonate-functionalised polyethylenes

Non-halogenated “all-in-one” flame retardant HDPE.

Synthesis of Polyethylene Glycol-9,10-dihydroxy Monostearate as Palm Oil-Based Polyol and Its Application on the Preparation of Polylactic acid/Polyurethane Block Copolymer

Synthesis of Polyethylene Glycol-9,10-dihydroxy Monostearate as Palm Oil-Based Polyol and Its Application on the Preparation of Polylactic acid/Polyurethane Block Copolymer

Synthesis and Evaluation of Polyethylene Glycol-4000-Co-Poly (AMPS) Based Hydrogel Membranes for Controlled Release of Mupirocin for Efficient Wound Healing.

Chronic wound healing is a major challenge for the health care system around the globe. The current study was conducted to develop and characterize chemically cross-linked polyethylene glycol-co-poly (AMPS) hydrogel membranes to enhance the wound healing efficiency of antibiotic mupirocin (MP). Free radical polymerization technique was used to develop hydrogel membranes. In an aqueous medium, polymer PEG-4000 was cross-linked with the monomer 2-acrylamido-2-methylpropane sulfonic acid (AMPS) in the presence of initiators ammonium peroxide sulfate (APS) and sodium hydrogen sulfite (SHS). N, N-Methylene-bis-acrylamide (MBA) was used as a cross-linker in preparing hydrogel membranes. Developed membranes were spherical, transparent, and had elasticity. FTIR, TGA/DSC, and SEM were used to characterize the polymeric system. Swelling behavior, drug loading, and release pattern at pH of 5.5 and 7.4, irritation study, ex vivo drug permeation, and deposition study were also evaluated. Formed membranes were spherical, transparent, and had elasticity. The formation of a stable polymeric network was confirmed by structural and thermal analysis. Evaluation of the drug permeability in the skin showed good permeation and retention capabilities. No irritancy to the skin was observed. Based on the results obtained, the present study concluded that the formulated stable network might be an ideal network for the delivery of mupirocin in skin infections.