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Neutron reflectivity, NR, and surface tension, ST, have been used to study the surface adsorption properties at the air-water interface of the anionic surfactant sodium polyethylene glycol monododecyl ether sulfate (sodium lauryl ...
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Neutron reflectivity, NR, and surface tension, ST, have been used to study the surface adsorption properties at the air-water interface of the anionic surfactant sodium polyethylene glycol monododecyl ether sulfate (sodium lauryl ether sulfate, SLES) in the presence of Al~(3+) multivalent counterions, by the addition of AlCl_3. In the absence of AlCl_3 and at low AlCl_3 concentrations monolayer adsorption is observed. With increasing AlCl_3 concentration, surface multilayer formation is observed, driven by SLES/Al~(3+) complex formation. The onset of multilayer formation occurs initially as a single bilayer or a multilayer structure with a limited number of bilayers, N, ≤3, and ultimately at higher AlCl_3 concentrations N is large, >20. The evolution in the surface structure is determined by the surfactant and AlCl_3 concentrations, and the size of the polyethylene oxide group in the different SLES surfactants studied. From the NR data, approximate surface phase diagrams are constructed, and the evolution of the surface structure with surfactant and electrolyte concentration is shown to be dependent on the size of the polyethylene oxide group. As the polyethylene oxide group increases in size the multilayer formation requires increasingly higher surfactant and AlCl_3 concentrations to promote the formation. This is attributed to the increased steric hindrance of the polyethylene oxide group disrupting SLES/Al~(3+) complex formation.
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The method for the formation of adhesive phase onto polyethylene (PE) fiber surface by passage of the PE fiber through hot PE solutions has been investigated for making composite materials reinforced by the PE fibers. When the PE ...
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The method for the formation of adhesive phase onto polyethylene (PE) fiber surface by passage of the PE fiber through hot PE solutions has been investigated for making composite materials reinforced by the PE fibers. When the PE fiber is treated by the low density PE (LDPE) solution in o-xylene in the range of 120 to 135 ℃, the tensile strength of the PE fiber is maintained at that of the original PE fiber. Adhesive strength between the PE fiber surface and LDPE phase formed on the PE fiber through the hot PE solution is found to be so high that the PE fiber itself is torn off. The application of the present method to PE fiber-reinforced PE composites will be expected.
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Calcium carbonate highly filled composites of a polyollefin plastomer (POP), and its blends with postconsumer linear low-density or high-density polyethylene (PC-LLDPE or PC-HDPE) were prepared and evaluated. The mechanical proper...
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Calcium carbonate highly filled composites of a polyollefin plastomer (POP), and its blends with postconsumer linear low-density or high-density polyethylene (PC-LLDPE or PC-HDPE) were prepared and evaluated. The mechanical properties of compounded POP and its blends were compared with those of a PVC-calcium carbonate formulation used for flooring applications. Tensile and impact properties of calcium carbonate-filled POP composites compare very favorably to the PVC-based formulation at filler loadings as high as 200 phr. Moreover, postconsumer LLDPE or HDPE can replace at least 50% of the POP in these composites without affecting their main properties. DSC analyses indicate that the synergism occurring in mechanical properties for some of the blend compositions, may be related to the ability of the individual polymers to cocrystallize in the respective blends. This article presents the results of a preliminary study. Continued research is expected to contribute toward a complete characterization of the compounded POP/postconsumer PE blends to establish if they can replace plasticized PVC compounds in some or all flooring applications.
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Functional polyethylene is a specialty polymer with unique set of properties and caters to a niche market. Currently, it is manufactured using high-pressure, high-temperature radical polymerization, or post-reactor (indirect) modi...
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Functional polyethylene is a specialty polymer with unique set of properties and caters to a niche market. Currently, it is manufactured using high-pressure, high-temperature radical polymerization, or post-reactor (indirect) modification methods. Insertion copolymerization of functional olefins with ethylene provides a low pressure, direct route to prepare functional polyethylenes. However, insertion copolymerization of functional olefins with ethylene poses several impediments and requires special considerations. This review presents the current strategies, examines the progress, and attempts to gauge the commercial potential of direct synthesis of functional polyethylene.
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In modern polymer composite technology, the use of waste products from other industries or processed waste is reasonable, but this requires more research. The purpose of the research presented in the article was to develop a metho...
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In modern polymer composite technology, the use of waste products from other industries or processed waste is reasonable, but this requires more research. The purpose of the research presented in the article was to develop a methodology for selecting the composition of modified polyethylene foam and to assess the flammability of the materials obtained. In these studies, the content of recycled polyethylene, as a result of solving optimization problems, was taken to be equal to 23% of the mass of the polymer. CO2 was used as the foaming gas. The structure of the polymer was modified with flame retardant. This made it possible to obtain materials belonging to the group of flammable, self-extinguishing materials, which significantly expanded the field of application of products based on polyethylene foam. Taking into account the possibilities of seamless insulation casings, the following systems of application of products based on polyethylene foam are considered floors under mechanical load on the ground; permafrost soil insulation; insulation of external building elements in harsh climatic conditions; floating floors.
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In this study, linear low density polyethylene (LLDPE)/clay nanocomposites with various clay content were prepared by melt processing using two different compatibilizers, maleic anhydride grafted polyethylene (PE-g-MA) and oxidize...
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In this study, linear low density polyethylene (LLDPE)/clay nanocomposites with various clay content were prepared by melt processing using two different compatibilizers, maleic anhydride grafted polyethylene (PE-g-MA) and oxidized polyethylene (OxPE). Effects of structure and physical properties of the compatibilizers on the clay dispersion and clay amount on the microstructure and physical properties of the nanocomposites were investigated. The OxPE was shown to significantly create interfacial interactions between the polymer phase and clay layers. Rheological behavior of the samples was examined by a dynamic oscillatory rheometry in linear viscoelastic region. Percolation threshold (phi_p) and corresponding aspect ratio (A_f) values were determined by analyzing the improvement in storage modulus at low frequency region depending on the clay loading. Lower percolation and higher aspect ratio values were obtained for the sample series prepared with the PE-g-MA than that prepared with the OxPE. Moreover, fractal size of the clay network above the percolation point was determined by the scaling law for physical gelation of colloidal flocks to quantify clay dispersion depending on the compatibilizer structure. It was found that the PE-g-MA yielded better clay dispersion and more exfoliated structure compared to the OxPE. Microstructural characterization of the samples was also characterized by XRD and TEM.
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The production of solid section products from highly oriented fibers by a novel compaction procedure is described for melt-spun and gel-spun polyethylene fibers, poly(ethylene terephthalate) and polypropylene fibers and Vectran li...
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The production of solid section products from highly oriented fibers by a novel compaction procedure is described for melt-spun and gel-spun polyethylene fibers, poly(ethylene terephthalate) and polypropylene fibers and Vectran liquid crystalline copolyester fibers. Differential scanning calorimetry and electron microscopy have been used to study the structure of the compacted polymers. For the most successful compaction, selective surface melting of a small fraction of each fiber enables the formation of a fiber composite of high integrity, where the matrix phase is formed by epitaxial crystallization of the melted fraction on the initial fibers, retaining a high proportion of their initial strength and stiffness. A nide range of potential applications is envisaged for the composites produced by hot compaction, In many cases these composites will be produced by thermoforming. In addition to the obvious advantages of high stiffness and strength, in several instances the unrestricted exploitation of unique properties of the fibers such as transparency to microwave radiation or low thermal expansion coefficients offer additional incentives for the use of these hot compacted materials rather than conventional fiber/resin composites.
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The global production and consumption of plastics has increased at an alarming rate over the last few decades. The accumulation of pervasive and persistent waste plastic has concomitantly increased in landfills and the environment...
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The global production and consumption of plastics has increased at an alarming rate over the last few decades. The accumulation of pervasive and persistent waste plastic has concomitantly increased in landfills and the environment. The societal, ecological, and economic problems of plastic waste/pollution demand immediate and decisive action. In 2015, only 9% of plastic waste was successfully recycled in the United States. The major current recycling processes focus on the mechanical recycling of plastic waste; however, even this process is limited by the sorting/pretreatment of plastic waste and degradation of plastics during the process. An alternative to mechanical processes is chemical recycling of plastic waste. Efficient chemical recycling would allow for the production of feedstocks for various uses including fuels and chemical feedstocks to replace petrochemicals. This review focuses on the most recent advances for the chemical recycling of three major polymers found in plastic waste: PET, PE, and PP. Commercial processes for recycling hydrolysable polymers like polyesters or polyamides, polyolefins, or mixed waste streams are also discussed.
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Blend prepared by melt mixing of thermoplastic material-elastomer have gained considerable atttention in recent years. Heat shrinkability of the polymer which depends on elastic memory can be introduced into the system in the form...
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Blend prepared by melt mixing of thermoplastic material-elastomer have gained considerable atttention in recent years. Heat shrinkability of the polymer which depends on elastic memory can be introduced into the system in the form of an elastomeric phase. The present study deals with the measurement of heat shrinkability of the blend of grafted polyethylene with CSM. Interchain crosslinking between grafted polyethylene and elastomer improves the shrinkability. CArystabllinity of the polymer blends also affectefd by interchain crosslinking,thus affecting the shrinkability. Probable interactions of the rubber and plastic phase are confirmed by IR spectroscopy. Extraction of the elastomeric phase is restricted due to interchain crosslinking as confirmed by SEM study.
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CaCO3 nanoparticles of around 60 nm were obtained by a co-precipitation method and used as filler to prepare low-density polyethylene (LDPE) composites by melt blending. The nanoparticles were also organically modified with oleic ...
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CaCO3 nanoparticles of around 60 nm were obtained by a co-precipitation method and used as filler to prepare low-density polyethylene (LDPE) composites by melt blending. The nanoparticles were also organically modified with oleic acid (O-CaCO3) in order to improve their interaction with the LDPE matrix. By adding 3 and 5 wt% of nanofillers, the mechanical properties under tensile conditions of the polymer matrix improved around 29%. The pure LDPE sample and the nanocomposites with 5 wt% CaCO3 were photoaged by ultraviolet (UV) irradiation during 35 days and the carbonyl index (CI), degree of crystallinity ((c)), and Young's modulus were measured at different times. After photoaging, the LDPE/CaCO3 nanocomposites increased the percent crystallinity ((c)), the CI, and Young's modulus as compared to the pure polymer. Moreover, the viscosity of the photoaged nanocomposite was lower than that of photoaged pure LDPE, while scanning electron microscopy (SEM) analysis showed that after photoaging the nanocomposites presented cavities around the nanoparticles. These difference showed that the presence of CaCO3 nanoparticles accelerate the photo-degradation of the polymer matrix. Our results show that the addition of CaCO3 nanoparticles into an LDPE polymer matrix allows future developments of more sustainable polyethylene materials that could be applied as films in agriculture. These LDPE-CaCO3 nanocomposites open the opportunity to improve the low degradation of the LDPE without sacrificing the polymer's behavior, allowing future development of novel eco-friendly polymers.
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