Copolymer Poly Ethylene Research Articles

Thermodynamic Interactions in Polydiene/Polyolefin Blends Containing Diverse Polydiene and Polyolefin Units

Thermodynamic interactions were investigated in blends of melts containing 1,4-polyisoprene (1,4-PI) and copolymers of 1,2-polybutadiene (1,2-PBD), poly(ethyl ethylene) (PEE), and/or polyethylene (PE) units. Specifically, two classes of blends were examined: one contained the polydiene 1,4-PI and a diene-olefin copolymer of 1,2-PBD and PEE units (1,2-PBD-co-PEE, with the PEE volume fraction varying from 0 to 1), and the other contained 1,4-PI and a fully olefinic copolymer of PE and PEE units (PE-co-PEE, with the PEE volume fraction varying from 0.05 to 1). The Flory–Huggins interaction parameter, χ, was measured using small-angle neutron scattering (SANS) for homogeneous blends at or close to their critical compositions. SANS data were analyzed through the Zimm method and fitting of the random phase approximation model to extract χ(T). Random copolymer theory (RCT) was applied to understand the resulting χ(T) behavior. In 1,2-PBD-co-PEE/1,4-PI blends, predictions using the RCT model showed excellent agreement with the measured χ(T), indicating the presence of random mixing and dominance of dispersive forces in these blends. By contrast, RCT failed to describe the χ(T) behavior in PE-co-PEE/1,4-PI blends. The PE-co-PEE/1,4-PI blends were further examined using lattice cluster theory and solubility parameter formalism, yet neither approach could explain the χ(T) behavior. The locally correlated lattice model, which correlates the equation of state properties with the polymer blend miscibility, was found to reasonably describe the phase behavior of PE-co-PEE/1,4-PI blends.

Adsorption of the rhNGF Protein on Polypropylene with Different Grades of Copolymerization.

The surface properties of drug containers should reduce the adsorption of the drug and avoid packaging surface/drug interactions, especially in the case of biologically-derived products. Here, we developed a multi-technique approach that combined Differential Scanning Calorimetry (DSC), Atomic Force Microscopy (AFM), Contact Angle (CA), Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), and X-ray Photoemission Spectroscopy (XPS) to investigate the interactions of rhNGF on different pharma grade polymeric materials. Polypropylene (PP)/polyethylene (PE) copolymers and PP homopolymers, both as spin-coated films and injected molded samples, were evaluated for their degree of crystallinity and adsorption of protein. Our analyses showed that copolymers are characterized by a lower degree of crystallinity and lower roughness compared to PP homopolymers. In line with this, PP/PE copolymers also show higher contact angle values, indicating a lower surface wettability for the rhNGF solution on copolymers than PP homopolymers. Thus, we demonstrated that the chemical composition of the polymeric material and, in turn, its surface roughness determine the interaction with the protein and identified that copolymers may offer an advantage in terms of protein interaction/adsorption. The combined QCM-D and XPS data indicated that protein adsorption is a self-limiting process that passivates the surface after the deposition of roughly one molecular layer, preventing any further protein adsorption in the long term.

Polyethylenes and Polystyrenes with Carbazole Fluorescent Tags

The increasingly intense consumption of plastics and, above all, their improper disposal in the environment are causing serious environmental concerns. Great efforts have been made for the development of new methods aimed at facilitating and speeding up the identification and sorting of different materials in the plastic recycling process. In this field, new strategies based on fluorescent tagging have been developed. This work concerns the synthesis and characterization of new fluorescent copolymers of polyethylene (PE) and polystyrene (PS), which are among the most produced and consumed plastic materials. The synthesized copolymers are potentially suitable for use as fluorescent markers of PE and PS. Ethylene-co-N-pentenyl carbazole (P(E-co-PK)) and styrene-co-4-(N-carbazolyl)methyl styrene (P(S-co-SK)) copolymers were prepared by Ziegler–Natta and free radical polymerization, respectively. If excited at 300 nm, both P(E-co-PK)s and P(S-co-SK)s give fluorescence emissions resulting in them being optically active. Moreover, due to the low amount of fluorescent units, they show chemico-physical properties such as those of their corresponding homopolymers (PE and PS). P(E-co-PK)s and P(S-co-SK)s have been also tested as fluorescent markers of PE and PS. The experimental results demonstrate that from PE/P(E-co-PK) and PS/P(S-co-SK) blends prepared using only 1% by weight of fluorescent copolymer, distinguishable fluorescent emissions can be still detected.

Efficient, Robust, and Flame-Retardant Electrothermal Coatings Based on a Polyhedral Oligomeric Silsesquioxane-Functionalized Graphene/Multiwalled Carbon Nanotube Hybrid with a Dually Cross-Linking Structure.

Graphene electrothermal coatings have attracted considerable attention in recent years due to their important application prospects in a broad range of areas. So far, lots of strategies have been explored for producing them. However, these strategies usually involve a complicated process with sophisticated conditions, limiting their scalable applications. Herein, we demonstrate a facile strategy for preparing efficient, robust, and flame-retardant electrothermal coatings from liquid-phase exfoliated graphene, by combining with multiwalled carbon nanotubes (MWCNTs) and polyhedral oligomeric silsesquioxane (POSS) nanoparticles. This relies on the use of a hyperbranched polyethylene copolymer that simultaneously bears UV-reactive moieties and POSS terminal groups. As a stabilizer, the copolymer can effectively promote the exfoliation of both graphite and MWCNTs in common organic solvents under sonication, rendering the POSS-functionalized graphene and MWCNTs well dispersible in the solvent. From their dispersions, POSS-functionalized graphene/MWCNT hybrid electrothermal coatings have been successfully prepared simply by vacuum filtration and UV irradiation under mild conditions. It has been confirmed that a dually cross-linking structure can be formed in the hybrid system. This significantly improves the thermal resistance of resultant coatings, which remain exhibiting a stable work state even at a temperature high as 280 °C without the occurrence of flammation. Meanwhile, this also endows them with excellent electrothermal performance and service stability. At a relatively low voltage, 15 V, the steady temperature can reach 188.4 °C, with a response time < 30 s; after being alternately folded for 2700 cycles or scraped 200 times, the coating still maintains a stable state. In particular, the process involved is relatively simple with mild conditions. With these features, the coatings obtained herein may find their important applications in the area of wearable devices and household heating systems.

Divergent silylium catalysis enables facile poly(vinyl chloride) upcycling to poly(ethylene-co-styrene) derivatives

Tandem hydrodechlorination/Friedel–Crafts alkylation of poly(vinyl chloride) (PVC) is achieved using silylium ion catalysts to prepare new styrenic copolymers of polyethylene.

Preparation and Characterization of Polyethylene Copolymers with PAH Side Groups as Carbon Fiber Precursors

Preparation and Characterization of Polyethylene Copolymers with PAH Side Groups as Carbon Fiber Precursors

Microplastics (MPs) distribution in Surface Sediments of the Freidounkenar Paddy Wetland

There is an urgent need to increase knowledge on the distribution of microplastics (MPs) in wetlands because these are sites of special ecological value and the ever-growing use of plastic can threaten such fragile ecosystems. This research assesses, for the first time, the occurrence of MPs in surface sediment of the Freidounkenar International Wetland (Northern Iran), a valuable habitat for migratory birds. A total of 1368 MP/kg were identified in the surface sediments of the wetland. The distribution of MPs in sediments per area was Ezbaran (36.5%), Western Sorkhrood (32.0%), Freidounkenar (20.1%) and Eastern Sorkhrood Ab-bandans (11.4%). The most contaminated sites were located close to agricultural fields, Damgahs (agroecosystems for birds), fishing areas and roads. Fibers and white-transparent and black-grey MPs constituted the dominant MPs in the surface sediment. The most abundant MPs were < 250 μm and these were made of nylon, polypropylene-low density polyethylene copolymer, polystyrene, low density polyethylene and polypropylene. The identification of MPs was carried out visually and supported with Scanning Electron Microscopy (SEM)-Energy Dispersive X-Ray (EDX) and micro-Raman techniques. There were weathering signs in large proportion of the MPs, according to SEM analysis, which evidences their formation from the degradation of other plastics. This is a comprehensive study on MPs in surface sediment of this sensitive internationally recognized ecosystem with high ecological value.

Glycidyl Cinnamate: Copolymerization with Glycidyl Ethers, In‐Situ NMR Kinetics, and Photocrosslinking

AbstractThe copolymerization of glycidyl cinnamate (GC) as a hitherto non‐polymerizable, photoreactive epoxide structure to aliphatic polyether copolymers is described, using the monomer‐activated epoxide ring‐opening polymerization (MAROP). Ethoxyethyl glycidyl ether (EEGE) and GC are copolymerized employing triisobutylaluminum (i‐Bu3Al) as a catalyst and tetraoctylammonium bromide (NOctBr4) as an initiator. The amount of GC varies from 3 mol% to 100 mol%, which results in apparent molecular weights in the range of 2600 to 4600 g mol−1and dispersities (Đ)below 1.34. Studies of the microstructure by in‐situ1H NMR kinetics indicate a gradient‐like distribution of EEGE and GC (reactivity ratios:rEEGE= 0.28;rGC= 3.6), applying the ideal copolymerization model for evaluation. A tentative explanation relies on differing bond lengths in the respective epoxide rings, as suggested by density functional theory (DFT) calculations. Mild and selective cleavage of the acetal protecting groups of EEGE is achieved using the acidic ionic resin Dowex, leaving the GC ester bonds intact (Mn = 1900–3700 g mol−1,Đ &lt;1.34). Thermal properties of the copolymers and the PGC homopolymer are investigated by differential scanning calorimetry (DSC). The crosslinking of P(G‐co‐GC) copolymers by UV irradiation allows hydrogel formation, which is confirmed by IR spectroscopy.

Comfort properties of moisture management finished bi-layer knitted fabrics: Part I - Thermal comfort

Six samples of bi-layer knitted fabrics have been given the moisture management finish, with the formulation containing amino silicone polyether copolymer, along with the hydrophilic polymer and wetting agent in the ratio of 1:2 with p H 5.5 at 60 o -70 o C. It is found that the chemical combination of wetting and finishing agents, and the experimental conditions are proved to be the best possible options taken in this study. The fabrics are tested for various thermal comfort properties, such as air permeability, thermal conductivity, thermal resistance, and water vapour permeability. The bi-layer fabric structure along with the application of the optimized moisture management finish makes the fabric more suitable for sportswear, exhibiting good comfort properties, like water vapor permeability, air permeability, thermal resistance, thermal conductivity, and moisture management properties. The results of the air permeability, water vapour permeability, thermal conductivity and moisture management tests indicate that, the microdenier polyester (inner)- microdenier polyester (outer) fabric treated with suitable optimized moisture management agent shows better thermal comfort property, providing high levels of comfort. Hence, these fabrics are preferred during summer, active and sportswear.

RHEOLOGICAL PROPERTIES OF METAL-FILLED SYSTEMS BASED ON HIGH-DENSITY POLYETHYLENE AND ALUMINUM

The paper considers the fundamental principles of the study of the rheological features of the melt flow of the initial high-density polyethylene and its filled compositions with aluminum powder, depending on the filler concentration, temperature and shear rate. To improve the compatibility of metal-polymer systems, a compatibilizer has been used, which is a graft copolymer of high-density polyethylene containing 5.6 wt. % maleic anhydride. The flow curves and the dependence of the effective viscosity on the shear rate of the initial high-density polyethylene and composites containing 0.5 wt. % and 5.0 wt. % aluminum powder has been determined. The regularity of the change in the effective viscosity of the melt on the temperature in Arrhenius coordinates has been established. Based on the curves obtained, the values of the activation energy of the viscous flow have been determined. A temperature-invariant characteristic of the composites viscosity properties has been drawn, which makes it possible to predict the change in the value of this indicator at high shear rates, close to their processing by extrusion and injection molding. The developed materials have been tested at the METAK LLC enterprise in Azerbaijan

Homogeneous {Ti2Ni} Heterotrinuclear Catalyst for Ethylene Polymerization and Copolymerization

We synthesized and spectroscopically characterized a new heterotrimetallic {Ti2Ni} ethylene (co)polymerization precatalyst containing one (α-diimine)NiBr2 and two (phenoxy-imine)TiCl4 scaffolds. Its calculated structure was investigated at the DFT B3LYP/LACVP** level. Our calculations showed that the titanium(IV) centers were in a slightly distorted trigonal bipyramidal environment, and the average Ti···Ni distance was 8.76 Å. The precatalyst was used for synthesizing polyethylene and ethylene copolymers. The results of GPC analyses showed that the obtained polyethylenes had the desired bimodal molecular weight distributions. The FTIR spectra revealed that polydispersity decreased as the vinyl end-group content increased. These results suggested that high mechanical resistance can increase the mechanical energy needed for processing the material. All 13C NMR signals were assigned to short-chain branches with specific spatial arrangements along the polymer backbone. The chain walking mechanism of branch formation controls the spacing and conformational arrangements between these short chains.

Use of a Graft Copolymer of Low Molecular Weight Polyethylene and Acrylic Acid in Carbon Black-Filled Polyethylene Compouns

Use of a Graft Copolymer of Low Molecular Weight Polyethylene and Acrylic Acid in Carbon Black-Filled Polyethylene Compouns

Physicomechanical properties of nanocomposites based on a mixture of graphite, technical carbon, and metal-filled polyolefins

The paper presents the results of a study of the effect of the concentration of graphite, technical carbon, aluminum and copper on the physicomechanical properties of nanocomposites based on polyolefins. High-density polyethylene, low-density polyethylene and polypropylene were used as polyolefin. To improve the technological compatibility of the mixed components of the mixture, compatibilizers were used, which are copolymers of polyethylene and polypropylene with maleic anhydride.

Distribution Characteristics and Source Analysis of Microplastics in Urban Freshwater Lakes: A Case Study in Songshan Lake of Dongguan, China

Current studies on microplastic pollution mainly focus on marine systems. However, few studies have investigated microplastics in an urban lake. This research intends to use an urban lake (Songshan Lake) as an example to explore the pollution characteristics of microplastics and use the principal component as well as the heat map analysis to discuss the relationships between different shapes of microplastics. According to this study, the average abundance of microplastics in the surface water and surface sediments of Songshan Lake were, respectively, 2.29 ± 0.98 items/m3 and 244 ± 121 items/kg; thin films were the major microplastics in both media; transparent this type of color has the most microplastic content. The particle size of microplastics was mainly 0.18–0.6 mm (43.3%) in surface water and 1–2 mm (48.3%) in surface sediments. The composition included five polymers: polyethylene (PE), polypropylene (PP), polypropylene–polyethylene copolymer (PP–PE copolymer), polystyrene (PS), and polyvinyl chloride (PVC), among which PE (47%) and PP (36%) were the main components. Principal component analysis (PCA) showed that there was a positive correlation among the four shapes of microplastics: films, fragments, foams, and fibers. The heat map analysis showed that the same category of shape distribution features may be similar for each sampling site.

Sol-gel derived mesoporous TiO2: Effects of non-ionic co-polymers on the pore size, morphology, specific surface area and optical properties analysis

Titanium dioxide (TiO2) nanoparticles were synthesized using sol-gel method and incorporated with co-polymers polyethylene glycol (PEG), polyvinylpyrrolidone (PVP) and pluronic F127 as pore forming agents. The samples were then calcined at 550 °C for 4 h to evaluate the effect of these co-polymers on the pore size and specific surface area. X-ray diffraction (XRD) analysis revealed a rutile phase with crystalline diffraction peaks. Crystal system of the observed rutile phase for all samples was tetragonal assigned to the group space P42/mm (136). Porous morphology was observed from scanning electron microscopy (SEM) images with spherical nanoparticles from all synthesized samples. Upon calcining at 550 °C, samples showed morphology with more and clear pores compared to as-prepared samples and mesoporous type was observed through Nitrogen adsorption – desorption isotherm measurements. Brunnauer–Emmet–Teller (BET) revealed the specific surface area of ∼69.82, 37.80 and 57.08 m2/g for TiO2@F127, TiO2@PVP and TiO2@PEG, respectively, after calcining at 550 °C. The pore size was found to be ∼13.01, 10.10 and 8.53 nm for TiO2@F127, TiO2@PVP and TiO2@PEG, respectively. Ultimately, the comparison of the non-ionic co-polymers on TiO2 is done to evaluate the morphological properties, specific surface area, porosity and optical properties that could promote TiO2 to act as an efficient electron transport layer in solar cells application.

Effect of temperature and pressure on the interfacial morphology and bond strength of thermally laminated glycol-modified polyethylene terephthalate/styrene-co-butadiene block copolymer films and comparison with coextruded (polyethylene terephthalate/styrene-co-butadiene block copolymer/polyethylene terephthalate) and polyethylene terephthalate/styrene-co-butadiene block copolymer/polyethylene terephthalate films heated with applied pressure after extrusion

This study focuses on controlling the interfacial adhesive strength between heat-sealed styrene-co-butadiene block copolymer (SBC) and glycol-modified polyethylene terephthalate (PETG) multilayer films. In comparison, the interfacial bond strength of coextruded PETG/SBC/PETG films was weaker. The lamella structures of SBC and free polybutadiene increased the interfacial adhesive strength. The coextruded films with applied thermal pressing were also examined. When exposed to heat, the interfacial adhesive strength improved. The butadiene layer segregated along the adhesive interface, as observed by transmission electron microscopy. The butadiene layer improved the interfacial adhesive strength. The applied pressure caused the butadiene layer to segregate in a parallel manner along the adhesive interface. The developed lamellar structure did not increase adhesive strength. We considered that the adhesive strength decreased due to a thinner butadiene layer with higher pressure. We concluded that adhesive segregation along the adhesive interface improved the bond strength.

Development of Antifouling Polysulfone Membranes by Synergistic Modification with Two Different Additives in Casting Solution and Coagulation Bath: Synperonic F108 and Polyacrylic Acid.

This study deals with the development of antifouling ultrafiltration membranes based on polysulfone (PSF) for wastewater treatment and the concentration and purification of hemicellulose and lignin in the pulp and paper industry. The efficient simple and reproducible technique of PSF membrane modification to increase antifouling performance by simultaneous addition of triblock copolymer polyethylene glycol-polypropylene glycol-polyethylene glycol (Synperonic F108, Mn =14 × 103 g mol−1) to the casting solution and addition of polyacrylic acid (PAA, Mn = 250 × 103 g mol−1) to the coagulation bath is proposed for the first time. The effect of the PAA concentration in the aqueous solution on the PSF/Synperonic F108 membrane structure, surface characteristics, performance, and antifouling stability was investigated. PAA concentrations were varied from 0.35 to 2.0 wt.%. Membrane composition, structure, and topology were investigated by Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The addition of PAA into the coagulation bath was revealed to cause the formation of a thicker and denser selective layer with decreasing its pore size and porosity; according to the structural characterization, an interpolymer complex of the two additives was formed on the surface of the PSF membrane. Hydrophilicity of the membrane selective layer surface was shown to increase significantly. The selective layer surface charge was found to become more negative in comparison to the reference membrane. It was shown that PSF/Synperonic F108/PAA membranes are characterized by better antifouling performance in ultrafiltration of humic acid solution and thermomechanical pulp mill (ThMP) process water. Membrane modification with PAA results in higher ThMP process water flux, fouling recovery ratio, and hemicellulose and total lignin rejection compared to the reference PSF/Synperonic F108 membrane. This suggests the possibility of applying the developed membranes for hemicellulose concentration and purification.

Реологические свойства металлонаполненных систем на основе полиэтилена низкой плотности и алюминия

The paper considers the fundamental principles of the study of the rheological features of the melt flow of the initial low-density polyethylene and its filled compositions with aluminum powder, depending on the filler concentration, temperature and shear rate. To improve the compatibility of metal-polymer systems, a compatibilizer was used, which is a graft copolymer of low density polyethylene with 5 – 7 wt. % maleic anhydride content. First, the values of the melt flow rate of low density polyethylene were determined depending on the concentration of aluminum powder. The filler concentration was varied in the range 0.5 – 30 wt. %. It is shown that with the loading of 0.5 wt. % aluminum powder, the maximum fluidity of the composites melt is achieved. The flow curves, the dependence of the effective viscosity on the shear rate of the initial low-density polyethylene and composites with 0.5 wt. % and 5.0 wt. % content of aluminum powder were determined. The theoretical substantiation of the regularities of changes in rheological properties is given. The regularity of the change in the effective viscosity of the melt on temperature in Arrhenius coordinates has been established. On the basis of the curves obtained, the values of the activation energy of the viscous flow are determined. It was found that with the loading of the filler, an increase in the activation energy of the viscous flow is observed. A temperature-invariant characteristic of the viscosity properties of composites has been constructed, which makes it possible to predict the change in the value of this indicator at high shear rates, close to their processing by extrusion and injection molding. The developed materials have passed industrial testing at the METAK LLC enterprise in Azerbaijan.

Физико-механические свойства многокомпонентных нанокомпозитов на основе полиолефинов

The results of a study of the effect of the various types of fillers concentration at the nanoscale level, zinc stearate, aluminum, technical carbon — on the physical and mechanical properties of nanocomposites based on polyolefins are presented. High density polyethylene, low density polyethylene and polypropylene were used as polyolefins. In order to improve the compatibility of polyolefins with fillers, a copolymer of high density polyethylene with maleic anhydride was used as a compatibilizer. The amount of maleic anhydride in the high density polyethylene was 5.7 wt %. Investigated such properties of nanocomposites as ultimate tensile stress, tensile yield strength, elongation at break, static bending strength and Vicat heat resistance. It was found that the use of a compatibilizer contributes to a significant improvement in the main physico-mechanical characteristics of nanocomposites, which indicates the technological compatibility of the mixed components of the mixture with the polymer matrix. It was found that in the presence of fillers, the elongation at break of the nanocomposites slightly decreases. It is shown that an increase in the content of technical carbon in the polymer matrix in the presence of 5.0 wt % concentration of aluminum is accompanied by an increase in the ultimate tensile stress and yield stress during stretching of nanocomposites with a maximum at a certain ratio of the mixture components. It was found that in polyolefins characterized by a relatively high degree of crystallinity, the maximum value of the ultimate tensile stress is achieved at a lower concentration of technical carbon.

PHYSICAL-MECHANICAL PROPERTIES OF COMPOSITES BASEDON LOW DENSITY POLYETHYLENE AND THERMALASH OF HOUSEHOLD WASTE

The article presents the results of a study of the influence of the concentration and disper-sion of household waste thermal ash on the physical-mechanical properties of composites based on low-density polyethylene. Thermal ash was obtained in a thermal furnace at the Balakhani enter-prise in Baku city at a temperature of 1200°C. We studied such properties of composites as tensile yield strength, ultimate tensile stress, elongation at break, and flexural strength. To study the effect of thermal ash dispersity on the properties, three grindings with a particle size were obtained: 80-110nm, 300-500nm and 1200-2000nm. It was found that low-density polyethylene nanocompo-sites with a particle size of 80–110 nm have relatively high strength properties (ultimate tensile stress, tensile yield strength, flexural modulus). It has been shown that, regardless of the dispersion of the particles, the maximum value of the tensile yield strength and ultimate tensile stress is achieved for samples containing 10 wt % of thermal ash. The maximum value of the flexural strength was established for samples with 20 wt % thermal ash content. In order to improve the compatibility of the components in the polymer-filler mixture, a compatibilizer of the Exxelor PO1040 brand was used, which is a graft copolymer of polyethylene with maleic anhydride (content of maleic anhydride 5.6 wt %). According to the data obtained, loading of the compatibilizer con-tributed to a significant improvement in the compatibility of the filler with the polymer, which was expressed in an increase in the strength properties of the composites. A theoretical substantiation is given for the regularities found in the change in the physical-mechanical properties of compo-sites depending on the dispersion and concentration of thermal ash. IR spectral analysis of the composites showed characteristic absorption bands of thermal ash alone and as part of low density polyethylene. The shift of absorption bands in the composition of the polymer matrix made it pos-sible to assert the probability of physical interaction of macrochains with the surface of thermal ash particles. The results of the study of the melt flow index of composites are presented. It has been established that loading of thermal ash in some cases leads to an increase in the fluidity of the melt of polymer composites.