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This paper presents an analysis of the stress evolution of high‐density polyethylene (HDPE) at loading, relaxation, and recovery stages in a multi‐relaxation‐recovery (RR) test. The analysis is based on a three‐branch spring‐dashpot model that uses the Eyring's law to govern the viscous behavior. The spring‐dashpot model comprises two viscous branches to represent the short‐ and long‐term time‐dependent stress responses to deformation, and a quasi‐static branch to represent the time‐independent stress response. A fast numerical analysis framework based on genetic algorithms was developed to determine values for the model parameters so that the difference between the simulation and the experimental data could be less than 0.08 MPa. Using this approach, values of the model parameters were determined as functions of deformation and time so that the model can simulate the stress response at loading, relaxation, and recovery stages of the RR test. The simulation also generated 10 sets of model parameter values to examine their consistency. The study concludes that the three‐branch model can serve as a suitable tool for analyzing the mechanical properties of HDPE, and values for the model parameters can potentially be used to characterize the difference among PEs for their mechanical performance. Highlights: Developed computer programs to determine parameter values automatically.Explained the unusual stress drop during stress recovery after unloading.Evaluated the statistical range of the parameter values for the good fitting. [ABSTRACT FROM AUTHOR]

Polyethylene (PE) is susceptible to environmental stress cracking (ESC). In the presence of an amphiphilic compound and subjected to stress, ESC starts with cavitation followed by slow crack growth and ends with brittle fracture. In this study, we used molecular dynamics simulation to study how branch ends which were chemically modified with vinyl acetate groups affect free volume coalescence around an amphiphilic compound, nonyl ethoxylate (NE), dispersed in branched PE models. Branch ends modified with vinyl acetate significantly impact the free volume coalescence dynamics around NE. Compared with methyl branch ends, vinyl acetate branch ends show a much higher affinity, as quantified by the corresponding radial distribution functions, for the hydrophilic ethylene oxide‐segment of NE. However, this is not the case for the hydrophobic ethylene‐segment. Interestingly, vinyl acetate branch ends tend to reduce the power (amplitude) of the free volume size fluctuations around both the ethylene oxide‐ and ethylene‐segments. Indeed, the powers of the fluctuations with different PE branching characteristics decrease with increasing vinyl acetate concentration. We believe that free volume coalescence leads to cavitation and that vinyl acetate branches could inhibit cavitation, thereby crack propagation in PE. The power results seem to be consistent with the experimental observation that the addition of copolymer ethylene vinyl acetate to low‐density polyethylene improves the ESC resistance of the blend. Highlights: Vinyl acetate branches reduce free volume coalescence activities.Vinyl acetate branches are attracted to the hydrophilic segment of NE.Cavitation likely starts from the free volume coalescence around NE. [ABSTRACT FROM AUTHOR]

To investigate the inhibition effect of chloroacetic acid allyl ester (CAAE) grafting modification on water‐tree aging in crosslinked polyethylene (XLPE), CAAE grafted XLPE (XLPE‐g‐CAAE) with different CAAE contents are prepared by melt blending and grafting modification method. The accelerated water‐tree aging experiments are carried out by the water‐blade electrode method. It is found that XLPE‐g‐CAAE has a great inhibitory effect on the water‐tree aging compared to XLPE, and XLPE‐g‐CAAE with 1.0 phr CAAE has the most significant effect on the water‐tree growth in the scope of the study. The microstructure of XLPE and XLPE‐g‐CAAE is investigated by thermal elongation, gel content, and static water contact angle, respectively. The results show that the grafting of CAAE containing polar groups can enhance the polarity of XLPE and improve the hydrophilicity, which has a dispersing effect on the polar water molecules entering the polymer. Thus, the water molecules are not easy to gather, inhibiting the water‐tree growth. Meanwhile, although the mechanical properties of XLPE‐g‐CAAE decrease to a small extent, and the relative dielectric constant and dielectric loss factor increase slightly, but the performance still meet the requirements of water‐tree resistance XLPE cable insulation. Highlights: CAAE with polar groups was successfully grafted onto XLPE.The polar groups can enhance the polarity of XLPE to improve the hydrophilicity.CAAE grafting can inhibit the water‐tree growth in XLPE.The dielectric properties meet the requirements of water‐tree resistance XLPE. [ABSTRACT FROM AUTHOR]

Plastic recycling facilities deal with single‐ and mixed‐stream plastic waste. Clean single‐stream waste is sold as clean flake, or the flake is converted to pellets for material handling. The flake conversion process uses a conventional melt‐phase extruder to convert extruded filaments that are cooled and then pelletized. Friction extrusion (FE), a solid phase processing technique that has successfully extruded metal and metal matrix composites with desired properties, has never been utilized to address its ability to process plastic wastes. In this study, FE was performed on single‐stream low‐density polyethylene (LDPE) and single‐stream polypropylene (PP). Consolidated filaments of 2.5 mm diameter were extruded from different polymers. The energy efficiency of FE was estimated based on extrusion rates. A potentially 50%–80% reduction in energy cost was calculated for FE compared to the conventional melt extrusion process. Thermal properties of pellets and extruded filaments were measured to evaluate the effects of FE process on the molecular and morphological structures of LDPE and PP. The thermal properties of PP before and after FE were not significantly changed. For LDPE, the melting and crystallization temperatures increased by 3 and 7°C while the degree of crystallinity decreased by 3%, probably associated with side chain realignment under shearing. Highlights: Direct extruded polyolefin into filaments without melting via friction extrusion.Estimated over 50% energy reduction compared melt extrusion process.This novel mechanical process does not degrade polyolefin material. [ABSTRACT FROM AUTHOR]

Polyolefin elastomer (POE) films can be used as a matrix for ultra‐high molecular weight polyethylene (UHMWPE) fiber‐reinforced composites via a hot‐melt process. However, the low melting temperature of UHMWPE limits composite processing. Therefore, this study aimed to create a film by blending POE with ethylene vinyl acetate (EVA) to reduce the film's processing temperature. Morphological analysis revealed that due to limited compatibility, EVA appeared as droplets within the immiscible POE matrix. T‐Peel tests demonstrated increased self‐adhesion in both the POE/EVA films and the fiber‐reinforced composites with higher EVA content. However, the mechanical properties of POE/EVA films, including tensile properties and shore hardness, were reduced due to EVA having lower inherent properties. UHMWPE fiber‐reinforced composites were fabricated from these films. In composites, optimal tensile and flexural properties were observed at lower EVA content. Scanning electron microscopy analysis suggests that the POE/EVA films are sufficiently infiltrated at 10–20 wt% EVA content. As EVA content increased, the drop weight impact test indicated a reduction in the maximum impact load and an increase in impact energy, attributed to improved adhesion and a broader distribution of impact load across the interface. Highlights: Polyolefin elastomer/ultra‐high molecular weight polyethylene composites' properties were studied with varying ethylene vinyl acetate (EVA) additive content.Add EVA to improve film impregnation when forming compositesIncrease in impregnation affects increase in properties of composites.Characterization shows that the optimal EVA content is 10–20 wt%. [ABSTRACT FROM AUTHOR]

This work presents an in‐depth experimental study aimed at assessing the impact of natural weathering on the behavior of high‐density polyethylene (HDPE) bottles. To this end, several analytical techniques were employed, including Fourier transform infrared spectroscopy (FTIR) to examine molecular changes, scanning electron microscopy (SEM) to study morphology, thermogravimetric analysis (TGA) to assess thermal properties, and tensile and compression tests to evaluate mechanical properties. The results obtained reveal significant changes in HDPE exposed to natural weathering. FTIR analysis enabled us to identify that the HDPE bottles had been subjected to an oxidation process initiated by the absorption of solar radiation during natural weathering treatments, while SEM analysis showed the presence of holes resulting from the detachment of material fragments after exposure, TGA analysis confirms the impact of natural exposure time on the decrease in the average molecular weight and chemical degradation of HDPE macromolecules, through a reduction in the initial degradation temperature and the maximum thermodegradation temperature. However, tensile and compressive tests showed a reduction in the mechanical strength of HDPE after exposure to natural conditions, with notable variations depending on environmental conditions, making the material damaged. These results enabled us to calculate the damage caused by three damage laws. These results offer important insights into the mechanisms of HDPE degradation under the influence of natural climatic factors, paving the way for the development of more resistant and durable packaging materials in the face of variable environmental conditions. Highlights: The objective of this study is to analyze and describe the effects of natural weathering on high‐density polyethylene bottles. This involves evaluating the deterioration of physicochemical, mechanical, and morphological properties. Additionally, three damage laws are employed to assess the extent of damage inflicted by this material.Analytical techniques were used, including SEM, FTIR, and TGA, tensile and compressive test. [ABSTRACT FROM AUTHOR]

Aiming at the problem of difficult to remove high‐carbon α‐olefin in polyethylene, the influences of operation conditions and devolatilization additives on the devolatilization of LLDPE/1‐octene system in an exhaust twin‐screw extruder are studied by headspace gas chromatography. The results showed that the devolatilization efficiency increases with the devolatilization temperature and vacuum. With the screw rotational speed, the content of liquid additives and the gas velocity of gas additives increasing, the devolatilization efficiency first increases and then decreases. The devolatilization difficulty of different grades of polyethylene varies due to the difference of the viscosities. When the volatile content is high, the effect of devolatilization additives is anhydrous ethanol > surfactant > water > nitrogen. When the volatile content is low, the effect of nitrogen on devolatilization is obviously better than anhydrous ethanol and water. Finally, a novel devolatilization process is proposed, that is, an evacuation system (vacuum degree 0.08–0.1 MPa) is set up in each stage of the devolatilization section, the anhydrous ethanol is introduced in the first stage, and high‐purity nitrogen is introduced in the second, third, and fourth stages, which can ultimately reduce the VOC content of LLDPE products to less than the target value of 50 ppm. Highlights: The devolatilization process is used to remove high carbon α‐olefins from LLDPE.Each additive has an optimal injection value.Ethanol is the most effective in the foam‐dominated devolatilization stage.Nitrogen is the most effective in the diffusion‐dominated devolatilization stage.A new additive‐enhanced twin‐screw extruder devolatilization process is proposed. [ABSTRACT FROM AUTHOR]

Trimodal polymerization of polyethylene has become a research interest in recent years due to its excellent potential for altering material properties and overcoming the limitations of the bimodal process. Here, we have comprehensively investigated the effects of manipulating polymerization parameters, such as split value (SV), hydrogen‐to‐ethylene ratio (H2/C2), and stage switching, on the rheological, thermal, and mechanical properties of synthesized trimodal high‐density polyethylene (HDPE). The synthesized samples were obtained through three consecutive stages in a slurry lab‐scale reactor. The results of molten state analysis demonstrate that recipe modification, particularly SV and H2/C2 balancing in the second and third stages, had a dramatic effect on the rheological properties including dynamic moduli, G′‐G″ crossover, and the shear‐thinning behavior. Concurrently, improvements in physio‐mechanical properties, such as sagging behavior and slow crack growth resistance (SCG), were observed compared to the bimodal resin. The thermal characterization indicates that the polymerization adjustments made did not notably impact the thermal properties of HDPE samples (e.g., Tm), throughout the all‐recipe manipulation. However, minor fluctuations in crystallinity and crystallization kinetics were observed which was presumably attributed to the molecular weight of the final resin. Overall, in our trimodal polymerization recipe, the HDPE powder is within the specified range of particle size distribution, which ensures excellent bulk density and flowability. Highlights: Influence of polymerization parameters such as split value, H2/C2, and stage switching in properties of trimodal HDPE.HDPE resin received from split value and H2/C2 balancing have superior SCG and sagging resistance.All HDPE samples synthesized by different recipes have similar thermal properties. [ABSTRACT FROM AUTHOR]

Sorted flexible polyethylene packaging waste was washed on a laboratory scale at both 25 and 40°C with water alone, with water and added NaOH, and with water and added detergent. The washed materials were then compounded using a twin‐screw extruder and injection molded. The results were compared with those for an unwashed and a large‐scale high‐intensity sample washed with NaOH at 70–80°C. An intensive washing combined with high temperature gave a lower extensibility both in the molten and solid states presumably because of a greater degradation of the recycled material. Washing with NaOH resulted in the lowest strain‐at‐break in both the melt and solid states, whereas washing with water alone or with a detergent gave similar strain‐at‐break levels. The melt strength, the stiffness and tensile strengths at room temperature, and the thermal properties were less affected by the washing procedure. Although the final properties seem to be useful in general there were still some trade‐offs between the washing condition and the degradation. While these results were expected, the influence of washing parameters on final product, for example, injection molded sample, has to our knowledge not been shown before especially regarding the mechanical properties. Highlights: Post‐consumer flexible polyethylene packaging waste was studied with a focus on washing conditions.The influence of washing conditions on thermal, rheological, and mechanical properties of recycled samples was investigated.High‐intensity washing at high temperature caused significant degradation of the material, this was to our understanding shown for the first time. [ABSTRACT FROM AUTHOR]

The aggregation of plastic waste results in immiscible polymer blends with inferior properties. This study explores the application of irradiation technology on polymer processing for its potential to increase the compatibility of immiscible polymer blends composed of poly(ethylene terephthalate) (PET) and linear low‐density polyethylene (LLDPE). When PET is radiated, it undergoes chain‐scission reactions resulting in the formation of free radicals. The extended lifespan of these free radicals in post‐irradiated PET provides an opportunity for inducing interface reactions with LLDPE during compounding through reactive extrusion. PET was irradiated with up to 50 and 200 kGy irradiation absorbance doses of gamma irradiation and then compounded with LLDPE in a twin‐screw extruder at three blend compositions. Analysis of rheological, morphological, and mechanical properties demonstrates the compatibility improvement in this immiscible polymer blend attributed to irradiation‐induced free radical interface reactions using post‐irradiated PET up to 50 kGy to conduct the reactive extrusion process. Highlights: Reactive extrusion process with post‐irradiated PET.Formation of interface reactions.Improving the compatibility of immiscible polymer blend. [ABSTRACT FROM AUTHOR]

Post‐industrial low‐density and linear low‐density polyethylene blown films are mechanically recycled for reutilizing in the production of blown films for packaging applications. This process enables the production of films with lower cost and similar properties while preserving the environment and lowering the amount of waste material disposed of. The mechanical recycling process results in the production of recycled pellets. This process includes chopping, washing, drying, and reprocessing. Mixtures of these recycled materials and their virgin form with various concentrations are shaped into blown films with inherent 70 and 30 wt% loadings for low‐density polyethylene and linear low‐density polyethylene components, respectively. Fourier transform infrared spectroscopy results of the recycled material show no contamination or chemical reaction with other materials. Gel permeation chromatography is carried out on the virgin and recycled low‐density polyethylene and linear low‐density polyethylene, and the results indicate the occurrence of chain session and crosslinking during the recycling process. The decline in the thermal properties of the samples, seen from the differential scanning calorimetry results, indicates the presence of crosslinks. The effect of structural changes caused by the recycling process on the rheological properties is studied. The miscibility of the blend components is evaluated by Cole–Cole plots and then further proved by Han and Van Gurp–Palman curves. Mechanical properties display an upturn following the presence of the crosslinkes. A decline in the optical properties in the films caused by the refraction of light by the crosslink structure in the film bulk and on the surface is evident. Highlights: LDPE and LLDPE were recycled according to the circular economy approachBlown films containing virgin and recycled LDPE and LLDPE were producedChain scission and crosslinking as a result of recycling were studiedRheological, thermal, mechanical, and optical properties were studied [ABSTRACT FROM AUTHOR]

The commercialized lithium‐ion battery separators are mass‐produced by mixing ultra‐high molecular weight polyethylene (UHMWPE) and paraffin oil (PO). The dissipative particle dynamics method is utilized to investigate the extrinsic factors (shear rate and cooling rate) and the intrinsic factors (the molecular chain length) on the microstructure of the UHMWPE‐PO mixture. For the mixture with UHMWPE possessing the same chain length, the high shear rate promoted a lower porosity (~28%) and smaller pores. In contrast, the slow shearing led to a high porosity (~40%) and larger pores. For the mixture with UHMWPE possessing short and long chains, the shear rate hardly affects the porosity and the pore size: the porosity was kept at ~30%, and the pore size was reduced by ~35% compared to the model with the same‐chain‐length UHMWPE. The cooling rate after shearing is the dominant factor in determining the porosity and pore size: the fast cooling raised the porosity by ~33% but hardly increased the pore size, while the slow cooling raised the porosity by ~74%, and the pore size by ~105%. The current study provided a deep understanding of the pore structure evolution in separator processing. Highlights: The effects of processing parameters on the pore structures are numerically illustrated.MD simulation and rheometer measurement assist DPD interaction parameters calibration for UHMWPE and PO.The low shear rate leads to a higher porosity and pore size.At the high shear rate, short UHMWPE chains reduce porosity but do not increase pore size.The fast‐cooling process slightly increases the porosity while keeping the pore size. [ABSTRACT FROM AUTHOR]

The crystallinity of polyethylene has been extensively studied, but in situ experiments designed to investigate the crystallization of PE and XLPE have hardly been discussed. In this work, the crystallization behavior of PE and XLPE was investigated by designing in situ crystallization observation experiments. We have compared the crystallinity, crosslinking, viscosity properties, and gas byproducts of different XLPE insulating materials. COMSOL simulations demonstrate that the DTAP and DTBP crosslinker initiated crosslinks have better insulating properties and cable stability than the DTBC and DTBTMC crosslinkers. The formation of an insulation layer initiated by the DTAP crosslinker is beneficial for improving the breakdown strength, processing performance, and stable operation of cables. Our work is of great significance for understanding the crystallinity of XLPE and determining the correct crosslinker. Highlights: In situ crystallization observation of PE and XLPE.Simulation of ultra‐high voltage cables.Finite element analysis.Investigation of gas byproducts in XLPE. [ABSTRACT FROM AUTHOR]

Agricultural waste fiber has huge utilization potential due to its abundant sources, renewability, and low recycling costs. In this process, up to 30 wt% tobacco stalk fiber (TSF) was compounded with high‐density polyethylene (HDPE) and interfacial modifiers using a grinder, melting‐blending mixer, and injection molding machine to prepare environmentally friendly TSF/HDPE composites, which have excellent mechanical properties and good water resistance. On this basis, the interfacial compatibility between TSF and HDPE was enhanced by adding a silane coupling agent KH550, titanate coupling agent 201, and maleic anhydride grafted polyethylene (MA‐g‐PE), which led to the improvement of mechanical properties of composites. The mechanical properties of the composites with 2% MA‐g‐PE were the best, while the tensile strength and flexural strength increased by 72% and 38%, respectively, compared with the unmodified composites. Fourier transform infrared (FTIR) spectroscopy showed that TSF was modified by different coupling agents and new chemical bonds were formed. The scanning electron microscopy images showed that the interfacial compatibility between TSF and HDPE was improved by the interface modifiers. This work confirms that it is possible to use TSF to prepare composites and provides a new way for resource utilization of tobacco stalk fiber. Highlights: TSF was incorporated into composites, boosting material sustainability.The interface compatibility between TSF and HDPE was greatly improved.Thermal and water absorption analysis can be used for composites design.Composites modified by 2 wt% MA‐g‐PE had optimal comprehensive properties. [ABSTRACT FROM AUTHOR]

Linear low‐density polyethylene (LLDPE) and different concentrations (5‐20 wt%) of magnesium hydroxide (MAH) as a filler either with or without the addition of graphene nanoplatelets (GNPs) were peroxide cross‐linked using dicumyl peroxide as a cross‐linking agent in a twin‐screw extruder. The mechanical, thermal stability, flame retardancy, morphological, and rheological properties of the prepared samples were investigated. The mechanical properties of the peroxide cross‐linked LLDPE samples with higher MAH and GNP in the matrix were significantly improvement compared to neat LLDPE. This indicates that the addition of MAH and GNP to the peroxide cross‐linked LLDPE matrix could be suitable reinforcing fillers to achieve better and enhanced mechanical properties, particularly tensile strength. Conversely, a significant decrease in the elongation at break values was found for peroxide cross‐linked LLDPE samples compared to neat LLDPE. Similarly, results of thermogravimetric analysis revealed remarkable thermal stability enhancement in the peroxide cross‐linked LLDPE samples with higher MAH and GNP compared to neat LLDPE. The results from UL94 test demonstrated that the peroxide cross‐linked LLDPE samples comprising higher MAH with GNP exhibited improved V = 0 rating compared to poor no rating (NR) for neat LLDPE. Furthermore, the scanning electron microscope and digital images shown improved flame retardancy properties for these samples because of the formation of protective char layer on the sample surface. The complex viscosity for the peroxide cross‐linked LLDPE samples, at lower frequency, increased with increasing MAH loading and further addition of GNP compared to neat LLDPE. Highlights: Cross‐linked polyethylene with flame retardant (FR) and nanofiller were prepared.Effects of cross‐linking and FR on the final properties of the polymer were studied.20wt% FR with 3 phr nanofiller promoted the final properties of the polymer.Higher filler loading in the polymer improved flame retardancy and thermal stability.Combined effect of cross‐linking and FR has shown major improvement. [ABSTRACT FROM AUTHOR]

Understanding the relationship between the fabrication process and the dielectric behavior of thermo‐responsive dielectric materials and accordingly optimizing the dielectric response behavior through simple regulation is critical to advancing their practical applications. For this purpose, we systematically analyze and demonstrate the effects of blow‐spinning process parameters, the feed rate and airflow pressure, on the orientation of poly(vinylidene fluoride) (PVDF) chains, the individual phase fractions of PVDF, the structure of the core‐sheath nanofibers, the mechanical properties, and the dielectric pulsing properties in polyethylene glycol (PEG)‐PVDF core‐sheath fiber films, and achieve the goal of effectively regulating the thermo‐responsive dielectric behavior. In particular, by increasing the airflow pressure, the polar phase fraction of the PVDF can be effectively increased, thus strengthening the dielectric pulsing effect. The significant influence of the processing parameters on the nanofiber structure also allows us to tailor the strength and toughness of the nanofiber films over a wide range by adjusting the feed rate and airflow pressure. Our work shows that the regulation of feed rate and airflow pressure can be used as an effective strategy to optimize the dielectric pulsing and mechanical properties of PEG‐PVDF films, enabling a simple and low‐cost performance optimization of thermo‐responsive dielectric materials. Highlights: Effective regulation of thermal dielectric behavior by tuning process parameters.Simple tuning of mechanical properties of nanofiber films over a wide range.High ratio of β‐ and γ‐phases of PVDF by solution blow spinning.Major polar phases contribute to improved mechanical and dielectric properties. [ABSTRACT FROM AUTHOR]

Ultra‐high molecular weight polyethylene (UHMWPE) was once the most widely used clinical hip prosthesis‐bearing component due to its exceptional mechanical qualities and biocompatibility. However, the poor wear resistance of UHMWPE limits its service life in vivo. Radiation cross‐linking is a common means to improve the wear resistance of UHMWPE, and highly cross‐linked polyethylene (HXLPE) acetabular cup is gradually becoming the first choice in clinical practice. The residual free radicals generated by the cross‐linking process can accelerate the oxidation process of the polymer acetabular cup, which is not conducive to the long‐term in vivo service process. Heat treatments such as annealing or melting and the addition of antioxidants are potential methods to improve the antioxidant performance of HXLPE in vivo. Research into the oxidation characteristics of polymer acetabular cup is crucial for enhancing their durability in vivo and ensuring their long‐term performance reliability. In this paper, the research progress focuses on the oxidation mechanism, the influencing factors of the oxidation process of polymer acetabular cups, and the methods to improve their oxidation resistance. It discusses the reliability of improving the service life of UHMWPE acetabular cup in vivo and other alternative methods. Highlights: Characteristics of polymer acetabular cups were systematically introduced.Mechanism of oxidative behavior of acetabular cup in vivo/in vitro was analyzed.Influencing factors of acetabular cup oxidation behavior were summarized.Methods for improving antioxidant properties of acetabular cups were summarized.New method was proposed to improve the antioxidant properties of acetabular cup. [ABSTRACT FROM AUTHOR]

Polymeric films are used in numerous applications in the biomedical area. The incorporation of antimicrobial agents into these materials can prevent their surface from acting as a source of contamination of viruses and bacteria. In the present work, cinnamon and eucalyptus essential oils were incorporated into low‐density polyethylene (LDPE) by melt extrusion, as confirmed by Fourier transform infrared spectroscopy. For the success of incorporation, talc was used as an oil carrier and fixer. Despite high processing temperatures used (up to 175°C), the oleophilic character of talc was able to minimize oil losses, as proven by thermogravimetry. Good thermal and mechanical properties evaluated by differential scanning calorimetry and tensile tests were confirmed. In addition, antimicrobial tests confirmed film activity against virus SARS‐CoV‐2 and bacteria Staphylococcus aureus and Escherichia coli. LDPE films incorporated with both oils showed significant antiviral properties against SARS‐CoV‐2, with viral titers reduction between 95.89% and 100%. Cinnamon oil showed more efficient antibacterial properties than eucalyptus oil, with relative bacterial growths of films next to zero (0.37% for E. coli and 2.07% for S. aureus). To the best of our knowledge, no previous work has developed plastic films incorporated with essential oils with confirmed antiviral properties against SARS‐CoV‐2. [ABSTRACT FROM AUTHOR]

With the development of degradation technologies such as chemical‐catalysis and bio‐catalysis, starch‐polyethylene (PE) composites have been revitalized as industrial packaging materials. However, starch and PE suffer from interfacial incompatibility. In this study, poly(octene ethylene) grafted glycidyl methacrylate (POE‐g‐GMA) was added at relatively low amounts (0–7 wt%) to construct robust structures between thermoplastic starch (TPS) and low‐density polyethylene (LDPE). Tensile strength increased by 36.39% with the addition of 1 wt% POE‐g‐GMA. Meanwhile, a smooth surface was observed by SEM, and a fibrillar cross‐linked structure appeared on the fractural surface of the blend. POE‐g‐GMA formed a stable "bridge" at the interface between TPS and LDPE, which increased the thermal stability of the blend as well. The crystallinity of LDPE increased from 20.5% (without addition) to 32.8% (with 1 wt% addition), whereas the average crystallite size decreased slightly. The optimal POE‐g‐GMA content was found to be 1 wt% based on mechanical and thermal measurements. The results of this study can provide a reference for improving the interfacial compatibility of biopolymers and fossil‐fuel‐based polymers. [ABSTRACT FROM AUTHOR]

The microstructure‐property relationships in multicomponent ethylene‐1‐alkene copolymers with different branching in the microstructures are demonstrated. The metallocene catalyzed linear low density polyethylene (mLLDPE), was miscible with both autoclave grade low density polyethylene (LDPE‐A) and/or tubular grade low density polyethylene (LDPE‐T). For these multicomponent systems, the rheological response was distinctly differentiating and sensitive to the microstructure of LDPE, at higher shear regimes. The thicker lamellae of LDPE‐T and/or LDPE‐A might co‐crystallize if there is a high density polyethylene‐like fraction present in the mLLDPE. Even though the macro parameters like density and melt index (MI) of the investigated multicomponent systems are comparable, the subtle differences in the microstructure manifested by type and distribution of comonomer and/or branching affected the sealing performance. Both high comonomer content and comonomer distribution in the mLLDPE matrix affording a higher fraction of material melting below 120°C were found to be critical for the heat sealing. The fraction of material melting at lower temperatures, attributed to the tertiary branches present in the hyper‐branched microstructure of LDPE‐A, participate in the sealing process, and lower the sealing temperature. It was evident that mLLDPE with asymmetric distribution of lamellae is more sensitive to the microstructure of the LDPE used. [ABSTRACT FROM AUTHOR]

Ultra‐high molecular weight polyethylene (UHMWPE) is one of the most prominent high‐performance thermoplastics for biomedical, leisure, and coating applications. Large‐scale recycling of UHMWPE is extremely difficult due to the high melt viscosity of the material as well as its exceptional chemical resistance and impact strength. There is a need for a commercially scalable methodology that can process the waste feedstock for mechanical recycling while sustaining the outstanding physical properties of the material. Solid‐state shear pulverization (SSSP) is a continuous, twin‐screw extruder‐based processing technique in which the low‐temperature application of shear and compressive forces impart changes in structure at different length scales to overcome the challenges of difficult‐to‐recycle polymers. This paper investigates the use of SSSP in mechanically recycling post‐industrial scrap UHMWPE (rUHMWPE) material from a local ski and snowboard manufacturer. The SSSP‐processed particles are flat, micron‐scale flakes with enhanced surface area, which can sinter very quickly when compression molded. The molded rUHMWPE samples in turn exhibit enhanced ductility and toughness compared to the as‐received scrap material, based on the tunable mechanochemical modification of the ethylene chains. [ABSTRACT FROM AUTHOR]

This paper explores a novel modification to the Bell Test (ASTM‐D1693) for minimizing its variability in failure time by the introduction of heat notching. The new notching technique for assessing environmental stress cracking resistance was evaluated with four different grades of polyethylene and compared to results using the ASTM standard for notching. Differences in both the failure time and the associated variability were witnessed with this technique, evaluated at various annealing conditions between the cold crystallization temperature and crystal melting temperature of a polyethylene. Best results were found using the midpoint temperature between these two conditions for the heated blade. Localized elastic moduli for the notched samples were obtained by force mapping via atomic force microscopy, showing decreased crystallinity content at the point of concentrated stress was favored for more consistent failure times. The work highlights the critical nature of local phase morphology at the notch in the assessment of environmental stress cracking resistance. [ABSTRACT FROM AUTHOR]

Concerned about environmental pollution, and aware of the comfort that polyethylene provides for daily human life, this work sought to replace a percentage of high‐density polyethylene (HDPE) with human or bovine hair. Hair is natural, abundant, light weight, non‐toxic, and disposed of as garbage. The main disadvantage of natural composites is the interfacial adhesion. To increase the interfacial adhesion between hair and HDPE, stearic acid or oleic acid was chemically anchored on the hair surface, which leads to an improved contact angle hysteresis and hydrophobicity. Dynamic‐mechanical properties of the composites were investigated focusing on the type of carboxylic acid used (stearic or oleic acid), hair length, hair type (human or bovine) and amount of hair used in the composite. Taking 40°C as a reference, using 15% of hair with a length of 1 ± 0.15 mm, the highest storage modulus value was obtained with HDPE with human hair modified with oleic acid, exceeding the value of the storage modulus of HDPE by 67.64%. Increasing storage modulus on composites indicates of interfacial interaction and chemical affinity improvement between hair and polyethylene. [ABSTRACT FROM AUTHOR]

Maleic anhydride‐grafted‐polyethylene was dynamically cross‐linked via reactive melt blending with 4,4′‐dithiodianiline. Thermal and mechanical properties of polyethylene vitrimers with different cross‐linking density were investigated. The results indicate that the degree of crystallinity decreased with increasing cross‐linking density. This behavior was directly related to short‐term and long‐term mechanical properties: vitrimers showed a decrease in yield strength and creep performance. The yield strength of PE vitrimers decreased linearly in relation to the degree of crystallinity. Polarized optical microscopy revealed that the cross‐links inhibit the growth of spherulites structure in polyethylene vitrimers. Thermogravimetric analysis indicated an increase in the onset degradation temperature and decomposition rate for vitrimers with increased cross‐linking density. The stiffness of the vitrimers decreased with increasing cross‐linking density which led to higher damping properties. Finally, it was demonstrated that reprocessing of polyethylene vitrimer was possible without significant impact in mechanical properties. [ABSTRACT FROM AUTHOR]

A series of polyethylene terephthalate‐polyethylene naphthalate (PETN) copolymer films with excellent oxygen barrier properties were prepared by introducing trace amounts of hydroxy‐terminated polybutadiene (HTPB) into PETN via in‐situ polymerization. The PETN‐HTPB copolymer films had strong oxygen scavengering capability. Due to the reaction of HTPB with oxygen, highly dense oxidized layers were formed. The introduction of HTPB also enhanced the nucleation of the PETN and increased crystallinity. The stronger oxygen scavenging capacity, the formation of the oxidized layer, and the increased crystallinity together greatly improved the oxygen barrier performance of the PETN‐HTPB films. When the HTPB content was only 1.0 wt%, the oxygen permeability of the films was as low as 18.2 cc mil m−2 day−1 0.1 MPa−1, which was about 7.5 times lower than that of the pure PETN film. The maximum oxygen scavenging amount of the samples was 8.3 ml g−1. The lowering of the diffusion coefficient instead of lowering of solubility was the main contributor to the decreasing permeability coefficient of the PETN‐HTPB films. This work provides a new idea for the preparation of high oxygen barrier polyester materials with oxygen scavenging capability. [ABSTRACT FROM AUTHOR]

This investigation proposes a natural fiber surface modification approach based on the use of a system of coupling agents (CAs) to improve the mechanical properties of polymer composites made of flax fibers and low‐density polyethylene. This system combines the coating of the NaOH treated (mercerized) flax fibers by a CA (Epolene C18 [M‐C18]) in a solution under moderated heat (70°C–80°C), followed by the addition of 1% or 3% wt. of another CA (Epolene E43 [M‐E43]) during the injection molding. The comparison between the solution modified and the neat and mercerized flax fibers using scanning electron micrograph (SEM), thermogravimetric analysis (TGA), and density underscored some differences ascribed to the presence of M‐C18 onto the modified fibers. The mechanical properties showed that the combination of solution modification and direct introduction during the injection‐molding step of 1% of M‐E43 was efficient as the corresponding composites exhibited an improvement of 9.1%, 15.9%, and 11.1% of his tensile, flexural, and impact strengths respectively compared to the neat fiber composite. Due to their good impact and flexural strengths, these composites can be suitable for automotive parts such as keyboard. [ABSTRACT FROM AUTHOR]

The relationship between career resin of carbon black (CB) masterbatch and the performance of bimodal polyethylene pipes (PE100) under ultraviolet (UV) irradiation and the long‐term stability of black PE100 with different comonomer content have been investigated. For this purpose, two different CB masterbatches varying in carrier resin were selected and added to two PE100 pipes. Samples were exposed to UV irradiation, and then thermal, mechanical, and rheological properties were explored using differential scanning coloriemetry (DSC), tensile, and rheometry analyses. Additionally, Fourier transformed‐infrared spectroscopy (FTIR) has been performed to characterize the structural changes of PE100 samples under UV irradiation. According to rheological results, the PE100 sample containing more comonomer underwent a higher degree of degradation. Thermal and mechanical results reveal that the masterbatch composed of high‐density polyethylene (HDPE) as carrier resin has a better influence on PE pipes' UV stability with less comonomer content. [ABSTRACT FROM AUTHOR]

The poor tribological performance of epoxy limits its application in the field of lubrication and wear protection, but there is still great potential for improvement. In this paper, polyethylene wax contained by silica core–shell particles was prepared and incorporated into the epoxy resin. The effects of particle content, normal load, and reciprocating linear velocity on the friction and wear properties of epoxy‐based composites were investigated. Due to the lubricating and anti‐wear effect of core–shell particles, the 10 wt.% amount can reduce at most the friction coefficient and wear rate of epoxy by 57% and 94%, respectively. The inflatable and burst core–shell particles, transfer film, and corrosion were observed on the worn surface. A mechanism referring to fracture, the release of lubricating core, and transfer film formed by a mixture of core and shell materials were deduced to explain the enhancement effect of core–shell particles in the epoxy matrix. That also suggests that the polyethylene wax@silica core–shell particles will be a potential lubricating and wear‐resistant additive of epoxy. [ABSTRACT FROM AUTHOR]

One of the most used resins in the plastics industry is polyethylene (PE). Although PE has good impact resistance and ductility, its low maximum use temperature and mechanical strength limit some commercial development, especially for load‐bearing applications. To get better overall performances, crosslinking is performed to improve the chemical, mechanical, and thermal properties of PE. Although PE can be crosslinked by using various chemical and physical methods, this makes the resulting polymers more difficult to recycle since a three‐dimensional (3D) network is created. In this review, we first describe the different crosslinking techniques for PE to manufacture crosslinked PE (XLPE) parts. Then, as more than half of the XLPE‐based products are disposed directly after use, we present several options to reuse and recycle these products to overcome this environmental issue and find a sustainable solution. A focus is made on mechanical recycling and de‐crosslinking techniques for XLPE to generate recycled‐XLPE (r‐XLPE). Finally, a conclusion is presented on the current situation and research gaps that must be filled by future works. [ABSTRACT FROM AUTHOR]

In the preparation of polyethylene (PE) microporous membrane, the stretching process of PE/liquid paraffin (LP) blend is of great significance for improving the mechanical properties and optimizing the pore size and its distribution. In this study, we have adopted a method that combines experimental investigation and numerical simulation to explore crystal structure transformation and residual stress distribution of PE matrix during the stretching process. First of all, the X‐ray diffraction, small‐angle X‐ray scattering test, and tensile strength test are used to analyze these PE/LP blend samples that are processed at different stretching temperatures (110°C, 115°C, 120°C, 125°C) and different stretching ratios (2 × 2, 3 × 3, 4 × 4, 5 × 5). It is found that a higher temperature or larger ratio is beneficial for crystallizing of PE long chains and affecting the tension strength. After the extraction process, the obtained PE microporous membranes have more uniform pore size distribution and an increased pore diameter according to the results of scanning electron microscopy and porosity test. It is attributed to the fact that residual stress is more easily stored in the amorphous region of PE microporous membrane. PE microporous membranes can have higher crystallinity and well‐dispersed crystal region by controlling a matched temperature and ratio. It is inspired for optimizing the technological parameters in industrial production. [ABSTRACT FROM AUTHOR]

The influence of molecular weight of olefin wax as a plasticizer on the processability and properties of ultrahigh‐molecular‐weight polyethylene (UHMWPE) was thoroughly investigated in this study. Two different grades of olefin wax (H5 and 210P) were used separately to plasticize UHMWPE. Comparative results were analyzed based on mixing torque, mechanical, thermal, thermo‐mechanical, and morphological aspects. The Gaussian mathematical model was applied to the internal thermo‐shear batch mixing torque data to predict processability and plasticization of the resulting compounds. A decrease in the peak torque value with increase in wax content revealed the plasticization effect. Across both types of wax (H5 and 210P) at 4, 8, and 10 phr content, the 10 phr H5 wax plasticized UHMWPE batch showed a minimum peak torque of 4.5 Nm with a broad mixing temperature window (∆T) of 32.4°C. The relatively low‐molecular‐weight wax (H5) seemed to be more efficient at uncoiling the entanglements among the amorphous phase of UHMWPE, perhaps because of its smooth interpenetration between ties. The lowest degree of crystallinity range (34%–40%) and the highest nucleation rate (0.9 min−1) were found with 10 phr H5 wax plasticized UHMWPE. The tensile strength of 30.5 MPa and elastic modulus of 127 MPa, achieved by the addition of H5 wax at 10 phr loading, confirmed the optimum effect of plasticization. The plasticization effect was also established from the loss moduli and Cole–Cole plots (log loss modulus vs. log storage modulus). A smaller number of multiple stress‐induced overshoots and the inclining approach toward the viscous dominant regime with temperature sweep were observed in the case of 10 phr H5 wax composition. Scanning electron microscopy (SEM) analysis revealed disappearance of interfacial crazing and interparticle boundaries progressively with the increase in H5 wax content. Overall, plasticized UHMWPE with 10 phr content of H5 wax showed the optimum processability and properties. [ABSTRACT FROM AUTHOR]

In this study, the influence of the addition of intumescent flame retardants (IFRs) on the non‐isothermal crystallization of high‐density polyethylene (HDPE) was studied. The investigations were carried out for polyethylene compositions containing two different IFRs, ammonium polyphosphate (APP) and a mixture of copper phosphate and melamine phosphate (CUMP). Both IFRs have been incorporated with a constant amount of 20 wt%. Non‐isothermal kinetic parameters were calculated from differential scanning calorimetry (DSC) analysis using the Jeziorny and Mo methods. The research demonstrates the appropriateness of using the latter approach to evaluate the HDPE‐based crystallization process changes. The results of the obtained kinetic parameters describing HDPE crystallization were related to the activation energy assessed by the Friedman method, microscopic analysis performed using polarized light microscopy, and wide‐angle X‐ray scattering (WAXS). Despite the increase in the activation energy (EX) of the flame retarded polyethylene series, the degree of crystallinity was comparable to that of unmodified HDPE due to a limited dependence effect of EX on relative crystallinity. Investigations made using polarized light microscopy showed an increase in the density of spherulite impingement for HDPE/IFRs. Moreover, despite introducing crystalline organic compounds, polyethylene did not reveal any polymorphic changes according to WAXS. [ABSTRACT FROM AUTHOR]

Materials able to store thermal energy can be a useful strategy to reduce energy consumption of buildings and to decrease greenhouse gases emissions. In this work, for the first time, the technique of salt leaching has been used to produce novel polyethylene foams containing different amounts of a microencapsulated phase‐change material (PCM) with a melting point of 24°C, to be potentially applied in building insulation. The microstructural, thermal, and mechanical properties of produced foams have been comprehensively investigated. The prepared foams were characterized by high values of open porosity (about 60%) and by density values around 0.4 g/cm3. Infrared thermography analysis demonstrated that the time required from the samples to reach a set temperature, thanks to the presence of PCM, was up to two times higher with respect to the reference foam. Therefore, these materials could store/release an interesting amount of thermal energy. Shore‐A measurements evidenced that the addition of PCM generally led to a softening of the foams. Tensile mechanical tests confirmed the softening effect provided by the addition of the microcapsules, with a decrease of the stiffness and of the strength of the material. Interestingly, strain‐at‐break values were considerably increased upon PCM introduction. [ABSTRACT FROM AUTHOR]

A 3‐aminopropyltriethoxysilane modified tetra‐needle like ZnO whiskers fillers containing Ziegler‐Natta catalyst is synthesized through a coagglomeration method. The surface of filler is fully wrapped with Ziegler‐Natta catalyst and the active sites are well dispersed in the catalyst. It exhibits good activity (28.7 g‐polyethylene/g‐cat) towards ethylene polymerization to give a composite of polyethylene and tetra‐needle like ZnO whiskers filler with enhanced thermal stability and mechanical properties due to the good dispersion and interface adhesion of the filler to polyethylene matrix. Therefore, this study provides a simple method to prepare high‐performance polyethylene with uniform filler distribution, good thermal stability, rigidity, and toughness. [ABSTRACT FROM AUTHOR]

Conductive polymer composites can be customized through the addition of conductive fillers to the matrix. Fillers added to a conductive polymer composite modify the mechanical properties of the material as well as the electrical properties. Previous work with conductive polymer composites determined that conductive polymers with carbon‐based materials exhibit more brittle behavior when compared with unmodified polymers, reducing strains to failure of the material. A conductive polymer with self‐healing functionality could be healed to repair damage. This work demonstrates a conductive polyethylene composite, which can simultaneously restore electrical and mechanical performance when heated with induction. Because carbon‐based conductive composites cannot be sufficiently heated for healing, aluminum flake added to the composite served as the susceptor for induction heating. Conductive polyethylene specimens with 20% aluminum flake by volume demonstrated similar mechanical behavior both during the initial test and after healing. [ABSTRACT FROM AUTHOR]

The morphology and orientation of polymer crystals are important factors which determine the performance of thin‐film, polymer‐based technologies such as organic electronic devices and gas separation membranes. Here, we utilize polymer‐substrate epitaxy to achieve a highly oriented crystalline morphology during thin‐film processing. To accomplish this, we employ matrix‐assisted pulsed laser evaporation (MAPLE), a slow physical vapor deposition process, to deposit linear polyethylene epitaxially atop a graphene substrate. Via MAPLE, we demonstrate the ability to achieve a film morphology comprised of well‐aligned, edge‐on crystalline lamellae. Furthermore, we show that MAPLE can be exploited to grow crystalline lamellae composed entirely of extended polymer chains which exhibit a near‐equilibrium melting temperature. Our study demonstrates that MAPLE, as a bottom‐up approach, can deposit polymer thin films with improved control over crystalline morphology. [ABSTRACT FROM AUTHOR]

In this work, methyltrimethoxysilane (MTMS) was used as a precursor, n‐hexadecyltrimethylammonium bromide (CTAB) as a surfactant, and EtOH/H2O as a co‐solvent, while 10 mM HCl and urea were used as acid and base catalysts to prepare silica xerogels and xerogel inside the cells of a polyethylene (PE) foam via a sol–gel process combined with ambient pressure drying. The xerogels and PE‐silica xerogel foams were characterized by scanning electron microscope (SEM), Brunauer–Emmett–Teller method (BET), and thermal conductivity. The results indicate that the xerogels have a three‐dimensional nanoporous structure, and the specific surface areas of the SiO2 xerogel and PE‐xerogel foam are 536 and 377 m2/g, respectively. The PE‐xerogel foam exhibited very low thermal conductivity (22–24 mW/m.K) compared with conventional insulation materials on the market (30–50 mW/m.K). The thermal insulation properties of PE‐silica xerogels were increased by 45% and 49% compared with neat PE foam. Additionally, the compressive modulus and density of the PE‐xerogel foam was increased by the presence of the silica xerogel. These PE‐xerogel foams are believed to be excellent candidates for thermal insulation applications in terms of cost/performance. [ABSTRACT FROM AUTHOR]

In this study, polyethylene (PP)/polyethylene terephthalate (PET)/multiwalled carbon nanotube (MWCNT) nanocomposites with nanofibrillary structure were processed by hot drawing‐assisted extrusion technology, and nonfoaming and microfoaming samples were processed by injection molding machine. Scanning electron microscope micrographs showed that when PET content was 2.5 wt%, PET fibers had a larger aspect ratio, which brought an outstanding promotion on microfoaming of PP matrix, and further details were provided by DSC and rheology analysis. When foaming sample loaded with 2.5 wt% PET and 3 wt% MWCNT, the best shielding effectiveness achieved 29.91 dB·cm3·g−1 in the test frequency range about 8.2–12.4 GHz. The results proved that the introduction of PET fibers optimized the microfoaming effect, and the uniform cell structure promoted the MWCNT dispersion and internal reflection of electromagnetic wave. Therefore, the shielding property is absorption‐dominated type and meets the requirements of lightweight and ultraefficient shielding demand of industry. [ABSTRACT FROM AUTHOR]

A series of novel intumescent flame retardant (IFR) based on melamine, neopentyl glycol, and aluminum diethylphosphinate were prepared and tested. In addition, the synergistic effect of the novel IFR and zinc borate (ZB) on the flame retardancy of LLDPE composites was investigated. The structures of novel IFR and ZB were characterized by X‐ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The limiting oxygen index (LOI) increased from 19.3% for the pure LLDPE to 27% for the 25 wt% IFR/5 wt% ZB composites and the composites achieved the desired V‐0 rating in the UL‐94 test. Thermogravimetric analysis showed that the addition of IFR/ZB reduced the pyrolysis rate of the LLDPE composites at high temperatures and increased the amount of the char residues, and the char residue of LLDPE‐5 reached 12.1 wt% at 700°C. Cone calorimetry (CCT) data showed that the peak of total heat release, heat release rate, and fire growth index were comparatively reduced, indicating that the addition of IFR/ZB decreased the fire hazard of LLDPE composites. The formation of a compact and thermally stable char layer on the surfaces of LLDPE composites was revealed from the scanning electrone microscopy images and digital photographs of the char residue after the CCT tests. [ABSTRACT FROM AUTHOR]

This work aims at studying the mechanism involved in the phase coarsening of ternary tri‐continuous polymer blends. To this aim, the phase coarsening behaviors of a co‐continuous polyethylene (PE)/polyethylene oxide (PEO) blend, and a tri‐continuous PE/polycaprolactone (PCL)/PEO blend during the quiescent annealing process are studied. Rheological characterization showed that the zero‐shear viscosities of PE and PCL phases were similar but much less than the zero‐shear viscosity of the PEO phase. The evolution of the microstructure of the blends during annealing was characterized using a characteristic length scale (λ). It was found that λ in both co‐ and tri‐continuous blends increased linearly in the early stages of annealing but the phase coarsening rate decreased in both systems at longer annealing times. In general, the tri‐continuous blend showed much faster phase coarsening rate. The effects of kinetic and thermodynamic parameters on the observed phase coarsening behaviors are discussed in detail. A new lubricating mechanism is proposed in which the deformation of the PCL layer between PE and PEO phases reduces the effect of high viscosity of the PEO phase and increases the phase coarsening rate in ternary blends. The obtained results provide a new insight into the role of the middle layer in tri‐continuous polymer blends on controlling the phase morphology of these systems. [ABSTRACT FROM AUTHOR]

This is the first study to showcase the use of maleic anhydride‐grafted polyethylene (MAPE) to compatibilize polyethylene (PE)‐rich blends, where polypropylene (PP) represents the minor phase. By first mixing PP with MAPE, and then adding PE, MAPE was assumed to be localized at the PE/PP interface. Microscopy analysis confirmed that MAPE led to a remarkably fine PE/PP/MAPE morphology, with PP being uniformly dispersed into PE and having an average diameter 267% smaller than that in the PE/PP blend. According to mechanical and rheological tests, this translated into a 14%, 20%, and 14% enhancement of tensile strength, tensile modulus, and tensile toughness, respectively, as well as a 10% and 20% drop in PE/PP viscosity mismatch and interfacial tension, respectively. Finally, PE/PP/MAPE tensile toughness and elongation at break were greater than those of virgin PP, while PE/PP/MAPE strength and stiffness were similar to the ones of neat PP. Therefore, this study provides industries with the possibility to utilize products rich in PE instead of those made of more expensive PP, while still keeping the level of performance high; hence, creating a paradigm shift in the development of advanced lightweight polyolefin materials with tuned functionalities. [ABSTRACT FROM AUTHOR]

Linear low‐density polyethylene (LLDPE) 7042, which has a butene comonomer, is widely used but has poor tear and dart strengths. For practical applications, small amounts of other materials can be blended with 7042 to effectively improve its properties. In this study, four blend resins and films (cast and compressed films) were prepared by blending 7042 with four LLDPEs (2045G, 9030, 23F, and 9085) in 8:2 ratios. The results indicated that after blending 2045G, 23F, or 9030 with 7042, the crystallization ability of the three blends was significantly suppressed and crystal size decreased. Moreover, the molecular chain can pass though more lamellar stacks in the blends, leading to an increased tie‐chain concentration. Therefore, the tear and dart impact strength of the blend films improved. In contrast, the crystallization ability of the 7042/9085 blend was only slightly suppressed and did not significantly impact its properties. These findings contribute to our understanding of the relationship between material structures and properties, demonstrating that LLDPE blends can be used to improve the tear and dart strengths of 7042. [ABSTRACT FROM AUTHOR]

Deep stretching has been found to decrease the cracking resistance of polyethylene (PE) in an aggressive environment. This idea has been adopted for developing a test method that uses indentation loading to generate a deep stretch of a PE plate so that time for crack generation is shortened. Work presented is to use finite element (FE) modeling to investigate the influence of indenter size and loading speed on the efficacy of the test method. Mechanical testing was carried out using cylindrical indenters of 7 and 13 mm in diameter on a plate that is supported so that only a 15‐mm diameter area can be stretched. Test results were used to calibrate material input data for the FE modeling and to establish the stress development and distribution during the deep stretch process. FE modeling considered three types of material input, one purely based on elastic–plastic deformation and the other two considering creep or damage during the deep stretch. All FE modellings suggest that the 13‐mm indenter is more effective than the 7‐mm indenter in introducing a monotonic total stress increase during the deep stretch, and thus the study concludes that the former should be used to introduce the deep stretch. [ABSTRACT FROM AUTHOR]

To produce polyethylene (PE) fibers with relatively high tensile strength but low cost, ultra‐high‐molecular‐weight polyethylene (UHMWPE)/high‐density polyethylene (HDPE) (UH) blend gels were prepared from paraffin oil and further fabricated into UH blend fibers by gel spinning. This research focused on the rheological properties of UH blend gels with high solid contents (SCs) ranging from 25 to 100 g/L, as well as morphology and mechanical properties of resultant gel‐spun UH blend fibers. The rheological measurements indicated that the apparent viscosity, shear storage, and loss moduli of the UH blend gels were not markedly increased compared with those of the UHMWPE gel with much less SC. No obvious solid–liquid phase separation occurred in UH blend gels at a temperature above the sol–gel transition temperature. UH blend fibers were prepared by drawing as‐spun fibers (draw ratio [λ] = 3) at 110°C to λ = 15, 45, 60, and 80, respectively. The orientation degree of fibril structure in UH blend fibers increased with increasing λ but the length of fibrils (Lfibril) showed a complex change. The Lfibril of UH blend fibers became larger due to chain arrangement in company with the transformation of the kebab structure to the extended shish structure when the λ was less than 45 but decreased during further elongation (λ = 60 and 80) because of fibril breakage and recrystallization. The change in morphological behavior led to the corresponding change in mechanical properties of resultant gel‐spun UH blend fibers. The tensile strength of gel‐spun UH55‐45 blend fiber (UHMWPE/HDPE = 5/5 and λ = 45) reached 15.6 cN/dtex, which could fulfill the requirement of mechanical properties in common application. [ABSTRACT FROM AUTHOR]

In this work, conductive polymer composites (CPCs) of bio‐based polyethylene (BioPe) containing different concentrations of carbon black (CB) were developed. By using oscillatory rheology analysis, a Newtonian plateau was observed in BioPe, and all BioPe/CB composites had a behavior of a pseudo‐solid and that composites with volume fractions ranging from 0.24 to 0.56 presented higher viscosity, storage, and loss modulus. This suggests the formation of a percolated network and by using the power‐law models, it was observed that the electrical percolation threshold was higher than the rheological percolation threshold. The electrical conductivity was measured using the four‐point probe method and a sigmoid model was used to predict the CPCs' electrical conductivity percolation threshold. The results indicated that the four‐point probe method presented satisfactory results according to the calculated standard deviations and voltage–current characteristics for each round of measurements considering the same ranging as used in rheology analysis. The analytical model used showed a coefficient of determination (R2) higher than 95%, allowing the prediction of the electrical conductivity of the CPC and the percolation threshold as a function of the volumetric fraction of the CB. [ABSTRACT FROM AUTHOR]

Ultra‐high molecular weight polyethylene (UHMWPE) powder was modified by surface treatment technology, then its wettability, dispersibility, mechanical, and tribological properties in polyurethane elastomer were studied. The testing results showed that after surface treatment, UHMWPE powder could infiltrate and disperse evenly in polyurethane, and build micro cross‐link with the contact surface of polymer substrate, which is conducive to enhancing the internal stress of polymer and improving the mechanical properties. With a small amount of modified UHMWPE being added into the casting polyurethane (CPU) elastomer, the right‐angled tearing strength increases and the abrasion loss decreases. Moreover, the elastomer surface self‐lubricating performance of CPU compounding with modified UHMWPE is enhanced: compared with the neat CPU sample, the average friction coefficient of the CPU samples with 5%, 10%, and 15% of modified UHMWPE is reduced by 46.3%, 41.5%, and 39.0%, respectively, and the surface wear resistance is improved; under the high‐load working condition, the CPU elastomer with 5% of modified UHMWPE has the optimal tribological performance. [ABSTRACT FROM AUTHOR]

Current study encompasses that the effect of corona treatment on the outer surface of transparent co‐extruded polyethylene films was at various levels by applying different wattages, in tandem with the blown film extrusion process. A maximum treatment of 42 dynes/cm was achieved at 4.5 KW of applied wattage. The heat seal joint strength of the films sealed at different combinations of treated/untreated surfaces was evaluated and an untreated/untreated surface combination was found to exhibit maximum strength (2.8 kgf/25 mm), while a treated/treated surface combination showed the minimum (1.41 kgf/25 mm) under identical conditions of sealing and testing. The peel adhesion to ascertain the treatment level on the treated surfaces was inspected by a standard Scotch tape method, and the results exhibited a linear relationship between the applied wattage and the pulling force of adhesion. The Fourier transform infrared spectroscopy (FTIR) spectra of the treated and untreated film samples in an attenuated total reflection (ATR) mode showed the peaks' characteristics mostly of polyolefin films. The morphologies of the treated surfaces displayed relatively rough surface compared to the untreated one. The barrier properties of the treated films in respect of water vapor and oxygen transmission rate do not undergo any appreciable change. [ABSTRACT FROM AUTHOR]

This work aims to describe the conductivity evolution of polymer composites (polyethylene filled with carbon nanotubes) during a shearing deformation. Rheo‐electric measurements were carried out to observe the shear‐induced fillers network modification. Extended steady shear forces the conductivity to evolve asymptotically to a steady level attesting to an equilibrium between structuring and break up mechanisms in the melted polymer. Numerous experiments were conducted to cover a wide range of shear rate from 0.05 to 10 s−1 and for carbon nanotubes concentrations between 1.3 and 2.9 vol%. A model is proposed to predict the conductivity evolution under shear deformation using a simple kinetic equation inserted in a percolation law. Structuring parameter was found to be solely dependent on the temperature whereas shear induced modification terms were found to be mostly driven by the shear rate and the fillers content. [ABSTRACT FROM AUTHOR]

The hierarchical multi‐mode molecular stress function (HMMSF) model developed by Narimissa and Wagner [Rheol. Acta 54, 779–791 (2015), and J. Rheol. 60, 625–636 (2016)] for linear and long‐chain branched (LCB) polymer melts were used to analyze the set of transient elongational and shear viscosity data of two LCB low‐density polyethylenes (1840H and 2426 k), and a linear poly‐(ethylene‐co‐α‐butene), PEB A‐780090 as reported by [Li et al. J. Rheol. 64, 177 (2020)], who had developed a new horizontal extensional rheometer to extend the lower limits of elongational viscosity measurements of polymer melts. Comparison between model predictions and elongational stress growth data reveals excellent agreement within the experimental window, and good consistency with shear stress growth data, based exclusively on the linear‐viscoelastic relaxation spectrum and only two nonlinear model parameters, the dilution modulus GD for extensional flows, and in addition a constraint release parameter for shear flow. [ABSTRACT FROM AUTHOR]

In this work, rotational molding was used to produce parts based on a blend of linear low‐density polyethylene (LLDPE) and polyamide 6 (PA6). In particular, the concentration of PA6 (0, 10, 20, and 30% vol) with and without a compatibilizer (Surlyn 9020) was investigated via two methods: dry blending in a high‐shear mixer and melt compounding in a twin‐screw extruder followed by pulverization. To determine the efficiency of the rotomolding process, similar parts were produced via compression molding. For rotational molding, dry ice (solid CO2) was used to create an inert atmosphere in the mold and the processing conditions were followed by the mold internal air temperature traces. From the samples produced, thermal, morphological, and mechanical properties were measured. The results showed that the rotomolded parts of the melt blended compounds generated smaller and better dispersed PA6 particles in the LLDPE matrix. This finer morphology led to improved mechanical properties, especially when the compatibilizer was present. But the latter was found to be more effective on the compression‐molded samples. [ABSTRACT FROM AUTHOR]