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Twenty types of polyethylene (PE) including high density polyethylene (HDPE) and linear low‐density polyethylene (LLDPE) with various viscosity were used to study the in‐situ formation of PE‐ ethylene propylene rubber (EPR) core‐shell rubber particles (CSRP) in polypropylene (PP) matrix by melt blending. The results show that PE and EPR cannot form CSRP if PE melt flow index (MFI) is lower than about 0.3 g/10 min. As a result, the impact fracture of PP/PE/EPR composite is brittle. If PE MFI is higher than 0.3 g/10 min, PE and EPR can form CSRP, leading to the ductile impact fracture of PP/PE/EPR composite. Interestingly, upper limit content of PE for the formation of CSRP depends on the type and viscosity of PE. For HDPE, upper limit content of PE tends to increase with the increase of its MFI, whereas it drops considerably for LLDPE. Understanding these relationships provides insights into optimizing the selection of core types and viscosity for enhancing the mechanical properties of polymer composites with core‐shell structure. This may potentially guide the development of cost‐effective and high‐performance polymer composites. [ABSTRACT FROM AUTHOR]

The recycling of waste plastics primarily involves physical modification and the addition of modifiers, often utilizing equipment such as twin‐screw extruders for miscible modification. Considering the widespread use of single‐screw 3D printing, improving the mixing efficiency of the single‐screw is crucial to achieve a "one‐stop" recycling modification that is suitable for 3D printing. This paper introduces a 3D printer equipped with a mixing screw (MS) and compares it with a conventional screw (CS). We conduct numerical simulations to investigate the pressure build‐up capacity, velocity streamline distribution, and the mixing effect of the MS. The mechanical properties, thermal characteristics, and molecular orientation of the recycled Polypropylene (rPP) and high density polyethylene (HDPE) mixture are investigated through experiments. The results show that the MS provides more effective elongational flows compared to the CS by breaking down the reinforcing materials into smaller particles. Additionally, toughening and modification experiments are performed on rPP and HDPE. The composites treated with the MS showed improved elongation at break (increased by ~111%), a stable melt crystallization temperature, and an enhanced mixing effect. This study on single‐screw 3D printers lays the groundwork for streamlining the plastic recycling process and increasing the reuse rate of recycled plastics. [ABSTRACT FROM AUTHOR]

It has been known that plastics with undegradability and long half‐times have caused serious environmental and ecological issues. Considering the devastating effects, the development of efficient plastic upcycling technologies with low energy consumption is absolutely imperative. Catalytic hydrogenolysis of single‐use polyethylene over Ru‐based catalysts to produce high‐quality liquid fuel has been one of the current top priority strategies, but it is restricted by some tough challenges, such as the tendency towards methanation resulting from terminal C−C cleavage. Herein, we introduced Ru nanoparticles supported on hollow ZSM‐5 zeolite (Ru/H‐ZSM‐5) for hydrocracking of high‐density polyethylene (HDPE) under mild reaction conditions. The implication of experimental results is that the 1Ru/H‐ZSM‐5 (~1 wt % Ru) acted as an effective and reusable bifunctional catalyst providing higher conversion rate (82.53 %) and liquid fuel (C5−C21) yield (62.87 %). Detailed characterization demonstrated that the optimal performance in hydrocracking of PE could be attributed to the moderate acidity and appropriate positively charged Ru species resulting from the metal‐zeolite interaction. This work proposes a promising catalyst for plastic upcycling and reveals its structure‐performance relationship, which has guiding significance for catalyst design to improve the yield of high‐value liquid fuels. [ABSTRACT FROM AUTHOR]

In this study, a small‐sized shredder machine equipped with spiral oriented double‐edged rotating and fixed blades was utilized to shred high‐density polyethylene (HDPE) waste. The performance of the shredder machine was determined based on the recycling and shredding efficiency, the percentage of retention, and the wear of its rotating and fixed blades. The wear of the blades was examined using an optical microscope, a scanning electron microscope, an energy dispersive x‐ray, and an x‐ray diffraction. High recycling (~95 %–98 %) and shredding (~66 %–70 %) efficiency, and low percentage of retention (~1.2 %–4.1 %) indicated a reliable performance of the shredder machine. The rotating blade exhibited higher wear at the back end, compared to the front end for the fixed blade. The wear of the blades was due to scratching and edge chipping. Formation of iron oxides during shredding did not cause significant changes in the hardness of the blades. Based on the evaluation, cost‐effective and time saving maintenance of the shredder blades could be achieved by gradual maintenance starting from the blade exhibited high wear. [ABSTRACT FROM AUTHOR]

Full‐field optical experimental techniques such as Digital Image Correlation (DIC) enable measurement of information‐rich heterogeneous strain states. The aim of Material Testing 2.0 is to capitalise on this and design experimental setups for efficient material characterisation using inverse identification techniques such as the Virtual Fields Method (VFM). In that case, however, a priori knowledge of the constitutive model is required, which sometimes is not a trivial task. This limitation can be overcome by identifying multiple constitutive models using the same DIC strain fields and comparing their performance. In this work, we present a methodology to evaluate model performance and compare different constitutive models based on quantitative metrics. DIC experiments were performed on an S‐shaped high density polyethylene test sample under uniaxial load. The heterogeneous DIC strain fields were used in combination with the VFM to identify parameters of hyperelastic constitutive models with increasing complexity. Two deterministic metrics, the equilibrium gap indicator (EGI) and the reconstructed axial force ratio (RAFR), were defined and used to compare the performance of these constitutive models. The impact of spatial smoothing on DIC strain fields was studied by calculating the EGI and RAFR using a digital twin of the DIC experiments. EGI and RAFR metrics provide complementary information regarding the material behaviour, and both are necessary to make an informed choice. In this case study, hyperelastic constitutive models were found not to capture the material stiffness well in the small strain regime. A linear‐elastic contribution exponentially decaying with the equivalent shear stress was added to the hyperelastic models and the corresponding model parameters identified using the VFM. The elastic‐hyperelastic constitutive models were found to perform better than their purely hyperelastic counterparts. [ABSTRACT FROM AUTHOR]

The aim of this paper is to determine the effect of polymer density, correlated to the comonomer content, and nanosilica addition on the mechanical and Environmental Stress Cracking Resistance (ESCR) characteristics of high‐density polyethylene (HDPE). In this regard, five HDPE samples with similar Melt Flow Index (MFI) and molar mass but various densities were acquired from a petrochemical plant. Two polymerization reactors work in series and differ only in the amount of 1‐buene comonomer fed to the second reactor. To ascertain the microstructure of the studied samples, GPC and SSA (successive self‐nucleation and annealing) analyses were accomplished. All samples resulted having similar characteristics but slightly various SCB/1000 C=7.26–9.74 (SCB=Short Chain Branching). Consequently, meanwhile studied HDPEs reveal similar notched impact and stress at yield values, the tensile modulus, stress‐at‐break, and elongation‐at‐break tend to demonstrate different results with the SCB content. More significantly, ESCR characteristic varied considerably with SCB/1000 C extent, so that higher amount of SCB acknowledged advanced ESCR. Notably, blending HDPE sample containing higher amount of SCB/1000 C, with 3 wt.% of chemically modified nanosilica enhanced ESCR characteristic by 40 %. DFT (Density Functional Theory) calculations unveiled the role of the comonomer, quantitatively by binding energies and qualitatively by Non Covalent Interaction (NCI) plots. [ABSTRACT FROM AUTHOR]

Highlights Microfibrillated cellulose (MFC) was uniformly dispersed in high‐density polyethylene (HDPE) using a large amount of surfactant, and composites were prepared after removing the surfactant at different contents. The structural, morphological, thermal, and tensile properties of these composites were systematically investigated. The results demonstrated an asymptotic relationship between the amount of surfactant removed and the number of removal cycles. A negative linear correlation was observed between the surfactant content and the tensile strength, tensile modulus, and storage modulus at −20 °C of the composites, while a positive linear correlation was found with the loss modulus at −20 °C. Excessive surfactant adversely affected the dispersion of MFC, as well as the mechanical properties and thermal stability of the composites. However, when the surfactant content was below 2.8%, its impact on the composite properties was minimal, and the tensile strength, modulus, and thermal stability of the composites were significantly improved compared to neat HDPE. These findings indicate that surfactant pretreatment is an effective strategy for dispersing MFC in non‐polar polymers, and controlling the surfactant content in the final product can effectively tailor the properties of the resulting composites. Confirms the relationship between surfactant content and MFC/HDPE composite properties. Surfactant content showed an asymptotic relationship with removal cycles. Surfactant content and mechanical properties exhibited a negative linear correlation. Surfactant content and thermal stability exhibited a negative relationship. Surfactant content had minor impact when below 2.8%. [ABSTRACT FROM AUTHOR]

Heptene‐graphitic nanoplatelets (HtGNP) serve as a filler for high density polyethylene (HDPE), generated through a mechanochemical reaction involving graphite and 1‐heptene. Various analyses indicate the efficient exfoliation of graphite into HtGNP, characterized by exceptional traits. Consequently, HtGNP & HDPE_5 nanocomposites, produced via the solution process, exhibit significantly increased tensile strength and Young's modulus, boasting corresponding increases of 27.7% and 13.7% compared to pure HDPE. Thus, owing to their outstanding performance, HtGNP emerges as a promising option in the form of a novel reinforcing additive for various hydrocarbon polymers. [ABSTRACT FROM AUTHOR]

Visualization and analysis of damage in honey peaches is important to reduce the occurrence of impact damage during postharvest handling. The finite element simulation method was used to visualize impact damage of honey peach. Firstly, the mechanical parameters such as maximum force, damage area, damage volume and absorbed energy during the collision between honey peaches and the surfaces of alloy steel, high density polyethylene (HDPE) and expandable polyethylene (EPE) were obtained by the collision device. Then, the elastic modulus and Poisson's ratio were obtained by compression tests of honey peach pulp. Finally, the process of collision between honey peaches and different material surfaces were simulated by finite element method. The results showed that the maximum error between the measured and simulated values of parameters were less than 25.1%. The study provides a reference for the selection of packaging materials for honey peaches and the biomechanical properties of various agricultural products. Practical applications: Impact damage is one of the most common mechanical injuries in postharvest handling of honey peaches, and it is of great significance to quantitatively study the impact damage of honey peaches to reduce the occurrence of impact damage of honey peaches during packaging and transportation. The study shows the feasibility of using the finite element method for quantitative prediction and assessment of impact damage in honey peaches. In addition, the selection of suitable packaging materials can be used to effectively reduce the occurrence of impact damage of honey peaches in the transportation process. The results of the study can not only provide theoretical support for the packaging and transportation of honey peaches and other aspects, but also provide a reference for the biomechanical properties of various agricultural products. [ABSTRACT FROM AUTHOR]

The recycling of polyolefins for multiple life cycles is becoming a legislative requirement in the South African plastics industry. This study shows that this cannot be a blanket requirement for all polyolefins. While HDPE displays good resistance to weathering, the decrease in molecular weight limits the maximum number of life cycles before which the resultant product has lost all integrity. Impact polypropylenes fare much worse during weathering and more than 50% of impact properties are lost within the first 12 months of exposure. The blending of virgin material into degraded material can recover some properties of HDPE but not in the case of impact polypropylenes. The same legislation can therefore not be applied to all plastics and specific targets should depend on polymer composition. [ABSTRACT FROM AUTHOR]

This study examines the impact of zinc oxide (ZnO) on the spectral, thermal, mechanical, and morphological characteristics of developed composites of high‐density polyethylene (HDPE). Composite samples were fabricated with different compositions of ZnO (0, 5, 10, 15, and 20 wt%) along with a constant quantity of hydroxyapatite (HA, 10 wt%) in pure HDPE. The synthesized hybrid polymer composites were characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), universal testing machine (UTM), and field emission scanning electron microscopy (FESEM) methods, allowing for a thorough assessment of their spectral, thermal, mechanical, and morphological properties, repectively. FTIR analysis revealed the presence of HA and ZnO metal vibrations in the hybrid polymer samples. The thermal stability was increased by the incorporation of different amounts of ZnO, and the decomposition temperature was increased from 319.31 to 412°C for 10 wt% of ZnO hybrid composites as compared to pure HDPE. DSC findings indicated that increasing the ZnO contents, prompted the degree of crystallinity to rise to 14.81% as contrasted to neat HDPE. It was observed that yield strength and ultimate tensile strength for the 10 wt% ZnO composite increased up to 51.85% and 31.72%, respectively, compared to pure HDPE. However, at higher loading of ZnO, surface cracks were observed, which is detrimental for composite materials. Hence, the improved attributes indicated that the synthesized ZnO/HA/HDPE polymer composites can be a promising material for biomedical engineering applications. [ABSTRACT FROM AUTHOR]

Reported herein is a continuous one‐step melt extrusion approach for high‐density polyethylene (HDPE) vitrimers. A grafting agent and a coagent were used to produce high‐performing vitrimers. Maleic anhydride (MA) served as a reactive agent to facilitate crosslinking, while dimethyl maleate (DM) acted as a grafting enhancer by reducing the surface energy of HDPE grafted with MA. For comparison, MA alone was also tested as a grafting agent. The vitrimers obtained displayed superior mechanical properties compared with HDPE. The storage modulus, as well as crystallinity, were determined for the HDPE vitrimers. These vitrimers are reprocessable, thus supporting recycling efforts despite their crosslinked nature, owing to very fast relaxation due to low activation energy for the transesterification reaction. Consequently, these vitrimers are not only recyclable but also exhibit enhanced thermal and mechanical properties compared with conventional HDPE. [ABSTRACT FROM AUTHOR]

Recently, passive radiative cooling (PRC) that realizes thermal management without consuming any energy has attracted increasing attention. However, few studies focus on low‐cost and robust PRC film fabricated by a facile and environmentally friendly method. In this study, via coextrusion blow film molding and water leaching, sandwiched PRC film (SPRCF) is efficiently prepared, and its skin and core layer are respectively high‐density polyethylene (HDPE) film and oriented ZnO@HDPE microfiber layer. Of note, such a sandwiched structure enables SPRCF to possess remarkable mechanical properties, abrasion, and weather resistance. Moreover, with the introduction of ZnO, SPRCF shows lower sunlight transmittance (≈3.8%) but higher mid‐infrared transmittance (≈88.8%), endowing it with remarkable PRC performance (the maximum cooling power of daytime and nighttime are respectively 73.8 and 96.7 W m−2). Furthermore, the decent self‐cleaning performance of SPRCF‐45 endows it with maintenance‐free features outdoors. This work proposes a facile and environmentally friendly method for preparing low‐cost and robust SPRCF, opening a new pathway to develop PRC film following the concept of polymer "structuring" processing. [ABSTRACT FROM AUTHOR]

Natural fiber‐reinforced polymer composites (NFRCs) are increasingly favored over synthetic fiber‐reinforced alternatives due to their beneficial properties and environmental sustainability. Mechanical properties of composites are critical to ensure optimized utilization of NFRCs. Here, this research explores the effects of different fiber parameters on the tensile strength of high‐density polymer composites reinforced with banana fiber and utilizes the Taguchi method for both experimental and statistical analysis of the outcomes. Three different parameters are considered here: weight fractions, fiber orientation angle, and plasma treatment to fabricate the composites using the compression molding process. Taguchi analysis revealed that fiber orientation angle has the greatest influence among the three variables, with plasma treatment and weight fraction following in impact on tensile strength. The composite that exhibited the highest tensile strength was determined to have a weight fraction of 10%, a fiber orientation angle of 90°, and a plasma treatment period of 5 min. This combination yielded a strength of 30.351 MPa. The analysis of the interaction between any two factors was done using contour plots. In order to compare the experimental tensile strength values with the anticipated values derived from the regression equation, regression analysis was carried out. Highlights: Composites were made up of recycled HDPE (rHDPE) from plastic bottles using a compression molding technique.The Taguchi method is applied to achieve an experimental design employing an L4 orthogonal array.Contour plot analysis is conducted to identify points of minimum and maximum responses, as anticipated from the results.Tensile strength was optimized to a maximum of 30.351 MPa. [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]

Nanoparticles are known to enable the modification of the properties of the material they are integrated into. In the context of ballistic protection, previous works have demonstrated that graphene and Montmorillonite (MMT) particles included in high‐density polyethylene (HD‐PE) and used as a matrix enable an increase in the ballistic performance, of consolidated woven aramid fabrics. Furthermore, the ballistic performance has been reported to be influenced by the in‐plane shear properties of the impacted materials. In this context, quasi‐static and high‐rate in‐plane shear tests have been conducted on two types of reinforcements, aramid, and carbon woven fabrics, consolidated by a high‐density polyethylene matrix enriched by graphene, MMT and a mix of graphene and MMT nanoparticles. The conducted investigations provide for the first time in the literature the results of high‐rate in‐plane shear tests on aramid woven reinforcement consolidated with nanoparticle‐enriched and not enriched high‐density polyethylene composites. Despite the use of the same reinforcement and enriched matrix material as in previous works of literature, no significant differences in terms of in‐plane shear behavior have been observed for any of the different types of nanoparticles integrated into the matrix. Nevertheless, the obtained results demonstrate a clear strain rate sensitivity of the tested materials. Highlights: Aramid and carbon fabrics were consolidated with nanoparticle‐enriched HD‐PEQuasi‐static and high‐rate in‐plane shear tests were conductedNo influence of the nanoparticles could be identifiedA clear strain‐rate sensitivity could be identified for both composites [ABSTRACT FROM AUTHOR]

In this paper, the gamma and neutron shielding behavior of chemically bonded high atomic number (Z), tungsten trioxide‐polyvinyl alcohol‐polyvinylpyrrolidone (PW), and bismuth oxide‐polyvinyl alcohol‐polyvinylpyrrolidone (PB) composites were reported at varying thickness. The PW and PB composites were prepared through the dissolution technique rather than the commonly used dispersion technique. The gamma and neutron attenuation characteristics of the composites were studied using 22Na (0.511 and 1.274 MeV energy) and 252Cf (0–10 MeV energy) sources, respectively. The half value layer of PW and PB composite was found to be 61.22 ± 0.914 mm and 48.29 ± 1.52 mm and the linear attenuation coefficient was found to be 0.115 and 0.144 cm−1 at 0.511 MeV, respectively. Further, the experimental gamma‐ray attenuation results were validated theoretically using Phy‐X software and found to be well in agreement with the experimental data. Both the composites also showed similar neutron shielding behavior when compared to the commercially used high‐density polyethylene (HDPE). The developed composites possess good mechanical properties as they did not show any cracks or wrinkles after undergoing 5400 bending cycles during the flex test, showing their high durability of flexibility. Thus, these composites are found to be suitable for shielding both, the gamma‐rays and neutrons. [ABSTRACT FROM AUTHOR]

The challenging melt processing of ultrahigh‐molecular‐weight polyethylene (UHMWPE) melt spinning hinders its efficiency and quality, which can be improved by processing aids that enhance its flowability. Building upon modifications of UHMWPE with high‐density polyethylene (HDPE), this article studies the effects of CaSt2, polyethylene glycol (PEG), silicone powder, and their compound additives on the processing performance of UHMWPE/HDPE blends. The modification effects and mechanisms are studied by analyzing processing torque, melt flow rate, viscoelastic activation energy, and rheological performance. The research results indicate that 1 wt% PEG significantly improves the processing flowability of UHMWPE/HDPE blends, and PEG mainly plays an internal lubrication role on the molecular chains of the blends. The combination of 0.5 wt% CaSt2 and 0.5 wt% silicone powder exhibits a synergistic effect of internal and external lubrication on the UHMWPE/HDPE blends melt processing, further improving the processing performance of UHMWPE/HDPE blends. Compared with unmodified blends, the maximum screw speed for obtaining qualified as‐spun filaments of UHMWPE/HDPE blends modified with CaSt2/silicone powder compound additives increases from 5 to 20 rpm, which means that the critical shear rate of the modified UHMWPE/HDPE blend melt processing is significantly improved. Meanwhile, the processing torque decreases by about 22%. [ABSTRACT FROM AUTHOR]

Hydrocarbons, when used as the medium for transition metal catalyzed organic reactions and olefin (co‐)polymerization, are ubiquitous. Environmentally friendly water is highly attractive and long‐sought, but is greatly challenging as coordination‐insertion copolymerization reaction medium of olefin and polar monomers. Unfavorable interactions from both water and polar monomer usually lead to either catalyst deactivation or the formation of low‐molecular‐weight polymers. Herein, we develop well‐behaved neutral phosphinophenolato nickel catalysts, which enable aqueous copolymerization of ethylene and diverse polar monomers to produce significantly high‐molecular‐weight linear polar polyolefins (219–549 kDa, 0.13–1.29 mol %) in a single‐component fashion under mild conditions for the first time. These copolymerization reactions occur better in water than in hydrocarbons such as toluene. The dual characteristics of high molecular weight and the incorporation of a small amount of functional group result in improved surface properties while retain the desirable intrinsic properties of high‐density polyethylene (HDPE). [ABSTRACT FROM AUTHOR]

In the present study, electrostatic powder coating waste was recycled and employed to reinforce high‐density polyethylene. The hydrolysis method was preferred to modify the powder coating waste of various systems, and they were mixed with high‐density polyethylene at various weight ratios. The mixtures were prepared in a mechanical mixer and then in an extruder to obtain a homogeneous mixture. This homogeneous structure was pressed into molds with a plastic injection device to obtain standard tensile samples. Mechanical and thermal tests were conducted on the samples. It was determined that the tensile stress of the sample decreased with the increase in filler content. The changes in sample tensile strength were investigated after the samples were aged. Three‐point bending strength of the samples was also investigated and it was observed that they became more resistant to vertical loads as the filler content increased. The Izod impact strength of the samples differed based on the filler type and weight ratio. Furthermore, mass loss in the produced mixtures was determined with thermogravimetric analysis. The matrix and filler bonding mechanisms were observed under an electron microscope. [ABSTRACT FROM AUTHOR]

ISO 23228:2011 proposed a testing method in which the plastic material, experimental resins or compounds for pipes and fittings, can be exposed to stress conditions that mimic internally pressurised end‐capped pipes. The stress conditions are mimicked by the use of a plaque specimen having a grooved reduced section called plane–strain grooved tensile (PSGT) specimens producing a biaxial state of stress under uniaxial loading. In this study, PSGT specimens were cut out from high‐density polyethylene (HDPE) pipes. Two shape ratios, ratio between the width and the groove thickness, were used. Both the axial and transverse displacements and strain fields were followed by a digital image correlation (DIC) camera during tensile and creep loading, both at room and high temperature; furthermore, DIC images were used to estimate the notch opening displacement. The increasing effect of the temperature in both the axial and transverse displacement and strain was highlighted. No significant effect of the width was noticed. The results have evidenced that, as the plane–strain condition in the width is assured during the tests, PSGT specimens can be used to mimic internally pressurised pipes under monotonic increasing or constant‐in‐time loading at both room and high temperature, but it must be better to use specimens with a higher shape ratio, that is, higher width. The results contribute to the 9th Sustainable Development Goal: Industry, Innovation and Infrastructure by promoting a sustainable industrialisation and fostering innovation. [ABSTRACT FROM AUTHOR]

Using a solution‐mixing method, this research aimed to fabricate high‐density polyethylene (HDPE)/ultra‐high molecular weight polyethylene (UHMWPE) composite materials with uniform dispersion. By incorporating a small quantity of UHMWPE as a nucleating agent, additional contact points were introduced to enhance the crystallization rate of the HDPE matrix. Thermal stretching experiments were conducted on composite systems with varying UHMWPE contents and molecular weight additions at different temperatures. Elevating the stretching temperature was found to decrease the yield strain and yield strength, extend the stage of tensile plastic deformation, and diminish the overall mechanical properties of the composite material. Notably, stretching at temperatures ranging from 90 to 110°C accentuated the development of internal crystal orientation structures. Under low strain conditions, crystal slip was observed to be concentrated, with single crystals undergoing continuous stretching and breaking, resulting in a decrease in the long period. Conversely, at high strains, the induced formation of oriented lamellar structures was observed. Highlights: Prepared HDPE/UHMWPE blends by UHMWPE with varying molecular weights.Analyzed the alterations in the HDPE/UHMWPE blends' internal crystal structure.Influence of UHMWPE addition, temperature on the evolution of crystal structure. [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]

This paper presents a comprehensive investigation into the manufacturing of high‐performance wood‐crosslinked high‐density polyethylene composites (WxHDPEC). In particular, the effect of maleated polyethylene (MAPE) treatment and concentration (0–50 wt%) of maple wood fibers is investigated. The samples were produced via dry‐blending followed by compression molding and a set of characterization was performed including chemical, morphological, mechanical, thermal, and physical properties. The gel content was found to increase with increasing wood fiber content, while the surface modification significantly improved the tensile strength (11%), tensile modulus (298%), flexural strength (138%), and flexural modulus (81%). Thermal analyses also showed improved thermal stability and higher thermal resistance for the treated composites. Finally, the Shore D hardness increased by 11.0 (from 61.5 to 72.5) and 12.1 (from 61.5 to 73.6) points, while the Shore A hardness increased by 7.5 (from 91.5 to 99.0) and 8.1 (from 91.5 to 99.6) points for the untreated and treated composites, respectively. These improvements are attributed to effective adhesion between MAPE‐treated wood fibers and the xHDPE matrix. The findings not only advance our understanding of these complex materials but also provide alternatives for various applications from construction to automotive engineering. Highlights: High‐performance wood‐reinforced crosslinked high‐density polyethylene was produced.The effect of maleated polyethylene (MAPE) treatment and maple wood fibers was studied.Higher crosslink density in MAPE‐treated wood‐xHDPE was obtained.Wood‐crosslinked high‐density polyethylene composites have better properties. [ABSTRACT FROM AUTHOR]

The craze‐crack mechanism occurring in high‐density polyethylene (HDPE) causing slow crack growth and environmental stress cracking is investigated in detail with respect to the relation of crack length and the related craze zone. This is essential for the understanding of the resulting features of the formed fracture surface and their interpretation in the context of the transition from crack propagation to ductile shear deformation. It turns out that an already formed craze zone does not inevitably result in formation of a propagating crack, but could also undergo ductile failure. For the examination, the full notch creep test (FNCT) was employed with a subsequent advanced fracture surface analysis that was performed using various imaging techniques: light microscopy, laser scanning microscopy, scanning electron microscopy, and X‐ray micro computed tomography scan. FNCT specimens were progressively damaged for increasing durations under standard test conditions applying Arkopal, the standard surfactant solution, and biodiesel as test media were used to analyze the stepwise growth of cracks and crazes. From considerations based on well‐established fracture mechanics approaches, a theoretical correlation between the length of the actual crack and the length of the preceding craze zone was established that could be evidenced and affirmed by FNCT fracture surface analysis. Moreover, the yield strength of a HDPE material exposed to a certain medium as detected by a classic tensile test was found to be the crucial value of true stress to induce the transition from crack propagation due to the craze‐crack mechanism to shear deformation during FNCT measurements. Highlights: Progress of crack formation in high‐density polyethylene is analyzed by different imaging techniquesDetermined growth rates depend on distinction between craze zone and crackThe ratio of the present crack to the anteceding craze zone is validated theoreticallyThe transition from crack propagation to ductile shear deformation is identifiedAn already formed craze zone may still fail by ductile mechanisms [ABSTRACT FROM AUTHOR]

Chemical recycling of polymers to monomers presents a promising solution to the escalating crisis associated with plastic waste. Despite considerable progress made in this field, the primary efforts have been focused on redesigning new monomers to produce readily recyclable polymers. In contrast, limited research into the potential of seemingly "non‐polymerizable" monomers has been conducted. Herein, we propose a paradigm that leverages a "chaperone"‐assisted strategy to establish closed‐loop circularity for a "non‐polymerizable" α, β‐conjugated lactone, 5,6‐dihydro‐2H‐pyran‐2‐one (DPO). The resulting PDPO, a structural analogue of poly(δ‐valerolactone) (PVL), exhibits enhanced thermal properties with a melting point (Tm) of 114 °C and a decomposition temperature (Td,5%) of 305 °C. Notably, owing to the structural similarity between DPO and δ‐VL, the copolymerization generates semi‐crystalline P(DPO‐co‐VL)s irrespective of the DPO incorporation ratio. Intriguingly, the inherent C=C bonds in P(DPO‐co‐VL)s enable their convenient post‐functionalization via Michael‐addition reaction. Lastly, PDPO was demonstrated to be chemically recyclable via ring‐closing metathesis (RCM), representing a significant step towards the pursuit of enabling the closed‐loop circularity of "non‐polymerizable" lactones without altering the ultimate polymer structure. [ABSTRACT FROM AUTHOR]

Polymer compatibilization plays a critical role in achieving polymer blends with favorable mechanical properties and enabling efficient recycling of mixed plastic wastes. Nonetheless, traditional compatibilization methods often require tailored designs based on the specific chemical compositions of the blends. In this study, we propose a new approach for compatibilizing polymer blends using a dynamically crosslinked polymer network, known as vitrimers. By adding a relatively small amount (1–5 w/w%) of a vitrimer made of siloxane‐crosslinked high‐density polyethylene (HDPE), we successfully compatibilized unmodified HDPE and isotactic polypropylene (iPP). The vitrimer‐compatibilized blend exhibited enhanced elongation at break (120 %) and smaller iPP domain sizes (0.4 μm) compared to the control blend (22 % elongation at break, 0.9 μm iPP droplet size). Moreover, the vitrimer‐compatibilized blend showed significantly improved microphase stability during annealing at 180 °C. This straightforward method shows promise for applications across various polymer blend systems. [ABSTRACT FROM AUTHOR]

The effects of iron oxide red pigment, organic red 254 pigment, titanium white pigment, and carbon black pigment on the properties of wood fiber (WF)reinforced high‐density polyethylene (HDPE) composites under outdoor aging conditions were investigated. The results indicate the addition of pigments in the outdoor aging process has a certain physical protection effect on the composites, effectively preventing the damage of ultraviolet rays on the WF/HDPE composites, and the mechanical experiments show that the pigments protect the composites more obviously in the first 3 months. Among them, the carbon black pigment had the best color‐fixing effect on the composites, with the ∆E* value is only 4.1, and the protective effect on the composites was relatively good due to its special structure. The quality change also verified again that the carbon black pigment has a certain protective effect on the plant fiber composites in the pre‐aging period outdoors, in which the mass of the composites with added carbon black pigment increased by 0.14%. Comprehensively, it shows that the addition of pigment cannot completely prevent the photo‐oxidation reaction of the composites from occurring, but it can effectively slow down the aging process of the composites and prolong the service life. Highlights: WF/HDPE‐modified composites were prepared by injection molding.The surface color of composites with pigment additions was analyzed.The addition of pigments effectively protects the composites.Mechanical and thermal properties have also been investigated. [ABSTRACT FROM AUTHOR]

The mechanical performance of parts produced by fused filament fabrication (FFF) has been limited due to the presence of voids and poor interlayer welding. Recent advancements in FFF have enabled the fabrication of void‐free objects with strong interlayer welding through the use of semicrystalline polymer shells such as high‐density polyethylene (HDPE) along with a high viscosity core polymer like acrylonitrile‐butadiene‐styrene (ABS). The zero‐shear viscosity (η0) of ABS is three orders of magnitude higher than HDPE making the ABS‐HDPE core‐shell configuration preferable. ABS holds the shape by preventing bulk flow and part bending while HDPE promotes full surface contact across the layers. Most polymers, however, are immiscible which causes a weak weld line along the core‐shell interface. Herein, maleic anhydride (MAH) is grafted to the butadiene segment of the ABS core thereby compatibilizing the interface with HDPE, improving the interfacial adhesion. Attenuated total reflectance‐Fourier transform infrared spectroscopy was employed to confirm successful grafting. Using a custom‐made die affording the core‐shell structure, the ABS‐g‐MAH is shown to improve the impact resistance by 253% and 16% compared to neat HDPE and ABS specimens, respectively. Additionally, a 10% increase compared to the unmodified ABS‐HDPE core‐shell configuration is observed. [ABSTRACT FROM AUTHOR]

Ground‐coupled heat exchangers (GCHE) have received significant attention over several decades as a result of increasing the world's energy demand and the need for reducing fossil fuels consumption. Prior studies have demonstrated the effectiveness of utilizing GCHE with refrigeration and heating systems. However, optimizing the performance of GCHE coupled with chillers for heat rejection, especially in extreme hot‐humid climates (where cooling towers are not very effective) is lacking in the literature. In this work, a ground borehole fitted with a coaxial‐tubes heat exchanger (BHE) is numerically simulated. Based on a wide range of data collected for the soil of Dubai, its real in situ thermophysical properties are characterized. The soil's upper layer thickness is relatively small and dry that operates in conduction mode, while the lower one is water‐saturated that works in coupled conduction‐advection mode. The study aims at optimizing the parameters advancing heat rejection into ground considering the actual properties of the soil of Dubai. The results indicate that the more feasible high‐density polyethylene pipes can perform as good as the steel ones. Also, a great finding based on the presented novel design is that insulating the inner pipe can increase the temperature duty by 55%. The proposed design of BHE is relatively inexpensive, more feasible and efficient, which is achieved for the first time based on a deep analysis of Dubai climate and soil. This makes the technology ready to be implemented for industrial applications in Dubai and other regions having a similar climate and soil nature. [ABSTRACT FROM AUTHOR]

Transportation of acidic fluids containing hydrogen sulfide (H2S) by flexible reinforced thermoplastic pipes can cause safety problems due to diffusion of H2S in the pipe. Herein, high-density polyethylene (HDPE) composites are prepared with a large amount of zinc oxide (ZnO) particles as absorbent fillers by melt-mixing via introducing maleic anhydride-grafted polyethylene (PE-g-MAH) and maleic anhydride-grafted poly(ethylene-co-octene) (POE-g-MAH) as dual-compatibilizer. By controlling the mass ratio of the two compatibilizers, ZnO particles can be encapsulated by PE-g-MAH and POE-g-MAH so that mechanical properties of the prepared HDPE/ZnO composites are improved owing to enhanced compatibility between the filler and the resin. By adding PE-g-MAH and POE-g-MAH with total 10 wt% in a mass ratio of 1/3, the HDPE/ZnO composite containing 50 wt% ZnO exhibits 37.3 ± 3.8 MPa of yield strength, 576 ± 16 MPa of flexural modulus, and 84.4 ± 1.4 kJ m-2 of notched Izod impact strength corrected to 311 ± 24.9 kJ m-2. After exposure in H2S at 0.1 MPa for 7 days, the diffusion distance of H2S in the composite is 659 ± 17 μm, demonstrating a high barrier ability on H2S via absorption. This study provides a feasible method for preparation of polymer composites with suitable mechanical properties for inhibiting H2S permeation in reinforced thermoplastic pipes. [ABSTRACT FROM AUTHOR]

The high volume of plastic waste and the extremely low recycling rate have created a serious challenge worldwide. Local distributed recycling and additive manufacturing (DRAM) offers a solution by economically incentivizing local recycling. One DRAM technology capable of processing large quantities of plastic waste is fused granular fabrication, where solid shredded plastic waste can be reused directly as 3D printing feedstock. This study presents an experimental assessment of multi‐material recycling printability using two of the most common thermoplastics in the beverage industry, polyethylene terephthalate (PET) and high‐density polyethylene (HDPE), and the feasibility of mixing PET and HDPE to be used as a feedstock material for large‐scale 3‐D printing. After the material collection, shredding, and cleaning, the characterization and optimization of parameters for 3D printing were performed. Results showed the feasibility of printing a large object from rPET/rHDPE flakes, reducing production costs by up to 88%. Highlights: Study: multi‐material recycling printability of PET‐HDPE.Large‐scale fused particle‐based 3‐D printing technically possible.Direct waste 3‐D printing rPET/rHDPE flakes, reducing production costs up to 88%. [ABSTRACT FROM AUTHOR]

Long‐persistent luminescent (LPL) materials have attracted considerable research interest due to their extensive applications and outstanding afterglow performance. However, the performance of red LPL materials lags behind that of green and blue materials. Therefore, it is crucial to explore novel red LPL materials. This study introduces a straightforward and viable strategy for organic–inorganic hybrids, wherein the organic ligand 1,3,6,8‐Tetrakis(4‐carboxyphenyl)pyrene (TCPP) is coordinated to the surface of a red persistent phosphor Sr0.75Ca0.25S:Eu2+ (R) through a one‐step method. TCPP serves as an antenna, facilitating the transfer of absorbed light energy to R via triplet energy transfer (TET). Notably, the initial afterglow intensity and luminance of R increase by twofold and onefold, respectively, and the afterglow duration extends from 9 to 17 min. Furthermore, this study involves the preparation of a highly flexible film by mixing R@TCPP with high‐density polyethylene (HDPE) to create a sound‐controlled afterglow lamp. This innovative approach holds promising application prospects in flexible large‐area luminescence, flexible wearables, and low‐vision lighting. [ABSTRACT FROM AUTHOR]

This study investigated the effects of mechanical recycling on the crystallization, mechanical, thermal, and rheological properties of recycled high‐density polyethylene (rHDPE), as well as vHDPE/rHDPE pellets and films made by different compositions. The results confirmed the presence of contaminants in rHDPEs, and the crystalline diameter of rHDPE is smaller than that of virgin high‐density polyethylene (vHDPE), with diameters ranging from 0.60 to 0.72 μm. The content of 75 wt% vHDPE in rHDPE film could repair the defects of crystalline morphology to approximate that of vHDPE films and significantly improve the elongation at break. The temperature required for the transition from crystalline to amorphous state of rHDPE film was 2°C lower than that of vHDPE, and the crystallization time and crystallinity declined compared to that of vHDPE. For rheological performance, the apparent shear viscosity and melt fluidity of rHDPE were worse than those of vHDPE. The blending of low rHDPE with vHDPE is a feasible option not only to reduce plastic waste but also to maintain acceptable properties of the blend composition. [ABSTRACT FROM AUTHOR]

Catalytic hydrogenolysis has the potential to convert high‐density polyethylene (HDPE), which comprises about 30 % of plastic waste, into valuable alkanes. Most investigations have focused on increasing activity for lab grade HDPEs displaying low molecular weight, with limited mechanistic understanding of the product distribution. No efficient catalyst is available for consumer grades due to their lower reactivity. This study targets HDPE used in bottle caps, a waste form generated globally at a rate of approximately one million units per hour. Ultrafine ruthenium particles (1 nm) supported on titania (anatase) achieved up to 80 % conversion into light alkanes (C1−C45) under mild conditions (498 K, 20 bar H2, 4 h) and were reused for three cycles. Small ruthenium nanoparticles were critical to achieving relevant conversions, as activity sharply decreased with particle size. Selectivity commonalities and peculiarities across HDPE grades were disclosed by a reaction modelling approach applied to products. Isomerization cedes to backbone scission as the reaction progresses. Within this trend, low molecular weight favor isomerization whilst high molecular weight favor cleavage. Commercial caps obeyed this trend with decreased activity, anticipating the influence of additives in realistic processing. This study demonstrates effective hydrogenolysis of consumer grade polyethylene and provides selectivity patterns for product control. [ABSTRACT FROM AUTHOR]

The isothermal crystallization kinetics of high-density polyethylene (HDPE) nanocomposites containing 0, 0.5, 0.75, and 2 wt% of pure and surfacemodified silica were evaluated at three crystallization temperatures (Tc) of 120°C, 121°C, and 122°C using differential scanning calorimetry (DSC) and applying Avrami, Tobin, and Malkin equations. According to Hoffman-Weeks theory, the values of the equilibrium melting point (T°m) of the nanocomposites decreased with increasing nanoparticle content and were higher in the samples containing AMS nanoparticles, owing to the larger crystal. The results of all three models offered the same trend according to which the change in the crystallization temperature influenced the nucleation mechanism and the crystallization rate. It was found that a greater number of spherulites can be formed via increasing Tc from 120°C to 122°C which also decreased the crystallization rate of the nanocomposites. At the crystallization temperature of 122°C, the lowest melting temperature was recorded for the samples, attributed to the formation of more crystals with a lower thickness. Moreover, in HDPE/AMS nanocomposites, the crystallization rate was higher than that of HDPE/PSN, ascribed to the positive effect of surface modification on nanoparticles. Highlights • Increased polymer/particle compatibility and isothermal crystallization. • Evaluating the nucleation and crystallization using different models. • The impact of isothermal crystallization temperature on crystallinity. • Variation of equilibrium melting point with the nanoparticle content. [ABSTRACT FROM AUTHOR]

Asphaltene is often regarded as an undesirable by‐product of petroleum processing, possesses vast reserves with little market value. The typical routes of consuming asphaltene, namely burning and landfilling, pose significant environmental challenges. In this study, low‐value asphaltene is converted into high‐value ethylated carbon clusters (ECC) using a supercritical ethanol technique. The resulting ECC powder demonstrates promising properties for high density polyethylene (HDPE) composite applications. The effects of incorporating ECC on the mechanical, gas barrier, and anti‐aging properties of the composite are investigated. Results show that a 1 wt.% ECC led to a 4.2% and 43.5% increase in tensile strength and elongation at break, a reduction of 45.8% and 30.7% in oxygen and carbon dioxide permeability. Furthermore, ECC exhibits effective UV spectrum absorption and conversion in the wavelength range of 400–600 nm, providing protection against UV spectrum damage to HDPE. The incorporation of ECC not only enhances the properties of polymer composites but also sequesters carbon within the polymer matrix, enabling the valorization of asphaltene while mitigating environmental impact. [ABSTRACT FROM AUTHOR]

In this study, soapstone waste originated from craftsmanship activities was used as an alternative filler (0–30 wt%) for a high‐density polyethylene (PE) matrix. The aim of this paper is to understand the effect of the filler particles on crystallinity, thermal stability and thermo‐mechanical properties of this newly developed composite material. Physico‐chemical characterization was performed by x‐ray diffraction (XRD) and Fourier‐transform infrared (FTIR) spectroscopy. Thermogravimetric analysis (TGA), oxidation induction time (OIT) and dynamic mechanical thermal analysis (DMA) were performed to assess the effect of the filler on the themo‐mechanical properties of PE. Thermal stability, measured by TGA, was enhanced, while OIT values reduced with filler content. A significant increase on the storage modulus of the composites (up to 148% in comparison with unfilled PE) was observed and this reinforcing effect was even more prominent at higher temperatures. XRD analysis revealed that the degree of crystallinity improved significantly with soapstone loading, which explains the substantial increase in stiffness observed. Increased crystallinity is also associated with higher strength, reduced residual stress, and better dimensional stability of end products, which can be particularly attractive for pressure pipe applications. [ABSTRACT FROM AUTHOR]

Temporarily consented tracks made from high‐density polyethylene (HDPE) mesh have been used to mitigate both the physical and ecological impacts on peatlands from low‐frequency vehicle usage. However, the impacts of mesh track removal or abandonment at the end of the consented period remain poorly understood. Over a 2‐year period, we studied replicate sections of abandoned mesh track which, at the start of the experiment, had been unused for approximately 5 years, on a UK blanket bog. Some sections were removed (using two treatment methods – vegetation mown and unprepared), whereas others were left in situ. Metrics were compared both between treatments and to undisturbed reference areas. Significant differences in surface soil moisture were found between abandoned and removed tracks depending on season. Control areas had higher volumetric soil moisture than track locations. Compaction was significantly higher across all track locations in comparison to controls (p < 0.001), but rarefaction was not recorded post‐removal, suggesting long‐term deformation. Overland flow events were recorded in rut sections for a mean of 16% of the time, compared to <1% in control areas. Sediment traps on the tracks collected 0.406 kg compared to 0.0048 kg from the control traps, equating to a per trap value of 7.3 g from track samplers and 0.17 g from control samplers. Erosion and desiccation features occurred on both removed and abandoned track sections. Both abandonment and removal of mesh tracks have a wide range of impacts on the physical properties of peatlands, suggesting that only where access is a necessity should such a track be installed. [ABSTRACT FROM AUTHOR]

Adhesion of contaminants on various polymer‐based devices during fluid‐substrate interactions is a common problem that can cause biofouling and corrosion. In this study, hierarchical structures with submicron features on polypropylene (PP), high‐density polyethylene (HDPE), and polycarbonate (PC) are fabricated by femtosecond laser ablation. The effect of the hierarchical structures on surface wettability, droplet impact, and bacterial attachment has been examined. Our results demonstrate that the structured polymeric substrates facilitate large contact angles and minimal interfacial adhesion, allowing droplets to roll off at a low angle of inclination below 5°. Further, rendering the hierarchical structures with a low‐surface‐energy coating can enable the surfaces to exhibit superamphiphobic properties. The low interfacial adhesion properties, as accounted by the large contact angles and small contact angle hysteresis, of such surfaces prevent bacterial attachment and biofilm formation. The findings provide a design principle for creating affordable biofouling resistant surfaces with a submicron topography that can be used for engineering and biomedical devices. [ABSTRACT FROM AUTHOR]

Acoustic emission (AE) technology provides a novel approach for studying the damage and fracture behavior of wood‐plastic composites (WPCs) during their application process. This method allows rapid and precise analysis of the mechanical properties of materials, which is a significant advancement for the emerging WPC industry. Hence, a blend of waste floor sanding powder (FSP) and rice husk (RH) reinforced recycled high‐density polyethylene (Re‐HDPE) was prepared by the extrusion method. The AE technique, scanning electron microscopy, and finite element method (FEM) were used to analyze the damage and fracture behavior of the composite materials under a three‐point bending test. The results indicated that the bearing capacity of RH/Re‐HDPE composites was slightly higher than that of FSP/Re‐HDPE composites. The AE technique can better illustrate the damage evolution and fracture process of composites and determine the damage degree and mode. Matrix cracking and deformation were more pronounced in the FSP/Re‐HDPE composites. Fiber breakage and delamination were more prominent in the RH/Re‐HDPE composites. In addition, repeated loading caused irreversible damage to the composite. The increase in temperature led to the attenuation of the AE signal and a decrease in matrix strength. However, when the temperature reached a certain point, the cumulative AE ringing count increased again because the higher temperature improved the fiber–matrix interface strength, which partially canceled out the negative effect. In addition, Abaqus was used for simulation analysis, and the running results coincided with the experimental value. Highlights: RH/Re‐HDPE and FSP/Re‐HDPE are sustainability and low‐cost composites.AE can determine the degree and mode of damage of WPC at different temperatures.The AE curves of RH/Re‐HDPE and FSP/Re‐HDPE all pass through four stages.Heating reduced the matrix strength and improved the interface strength of WPC.The results of FEM were consistent with the experimental results. [ABSTRACT FROM AUTHOR]

In this work, an attempt was made to use recycled thermosetting polymer waste (RTPW) to reduce the environmental impacts. The RTPW and high‐density polyethylene (HDPE) were used to fabricate the composites using melt mixing, a twin‐screw extruder, and an injection molding machine. The weight ratios varied between the HDPE/RTPW: 100:0, 95:5, 90:10, and 85:15 and subjected to different thermal property studies. The thermal properties were evaluated by melt flow index (MFI), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), heat deflection temperature (HDT), and VICAT softening temperature (VST). Results showed a noticeable MFI increase from 9.3 to 14.6 g/10 min in HDPE + RTPW (95:5) composite samples. It was ascribed to the presence of RTPW, resulting in reduced viscosity. DSC reported a minor change in the melting temperature of HDPE due to adding 5% RTPW and 6% polyethylene‐grafted maleic anhydride. These results suggested that the HDPE's crystallinity was minimally changed. Similarly, the onset and end‐set temperatures were increased by incorporating RTPW in TGA, highlighting the influence of thermosetting polymers. Then, the HDT and VSTs were improved by adding RTPW. These observations collectively demonstrate that using RTPW enhances the thermal behavior of HDPE composites while promoting environmental sustainability. Highlights: Composites made using RTPW and HDPE.Addition of thermoset waste improved the thermal behavior of samples.Different weight ratios were followed: 100:0, 95:5, 90:10, and 85:15.MFI increased to 14.6 g/10 min for HDPE + RTPW (95:5).HDPE exhibited a minor change in melting temperature in DSC analysis. [ABSTRACT FROM AUTHOR]

Elastomeric polymers such as high‐density polyethylene, have a variety of desirable features, that have supplanted traditional materials. However, high‐density polyethylene (HDPE) shows inadequate wear resistance, which limits its use for industrial applications, particularly in low‐load‐bearing applications such as flexible energy harvesting devices and sensors. The current work is engrossed in investigating the influence of hybrid reinforcements CaCO3 particles and bentonite nano clay as secondary reinforcements in high‐density polyethylene (HDPE)‐based composites on the wear and friction properties. The reinforcements were melt compounded with HDPE using a Brabender mixer and sampled using an injection molding machine. The wear test (ASTM G‐99‐04) was performed by a pin‐on‐disk tribo‐tester. In comparison to a base matrix, the synthesized hybrid composite achieved the maximum improvement in wear rate of 93%. The results revealed that there is a significant improvement in wear resistance. Morphological analysis revealed that due to the encapsulation and compatibilization effect of bentonite nano clay the hybrid composite exhibited improved wear performance. The results signify the synergistic effect of filler particles resulted in sufficient bonding for stress transfer due to the encapsulation of CaCO3 by nano clay. The wear mechanism observed optically was abrasion, fatigue, and adhesion wear that changed with the change in the weight percent of nanoparticles. Finally, the prepared composite with enhanced tribological properties such as low wear rate, low friction coefficient, and enhanced morphology can be used in low load‐bearing wear applications such as turbo nanogenerators and piezo nanogenerators. Highlights: Bentonite nano clay and CaCO3 dispersed homogeneously in HDPE matrix.Wear resistance of HDPE increases by reinforcing particles (nano‐clay and CaCO3).Micro‐cutting, deformations, and particle husks were the possible wear mechanism.Encapsulation effects the hybrid composite to exhibit improved wear performance. [ABSTRACT FROM AUTHOR]

We have demonstrated the significant impact of high density polyethylene (HDPE) crystallinity and structural morphology on the tensile strength of 60/40 NR/HDPE polymer blend composites. Introducing nanoscale Boron Carbide (B4C‐type compounds) fillers noticeably changed the crystallinity and morphology of HDPE, leading to the formation of fine spherulites. Conversely, microscale fillers mainly impacted the crystallinity while preserving a coarse architecture. Although both composites experienced a reduction in crystallinity, the nanocomposites outperformed microcomposites and even the pristine polymer blend in terms of strength, implying the effect of a fine structure. The nanocomposite with a filler loading of 2 wt% exhibited the highest strength. This investigation provides novel insights into the interplay between crystallinity, HDPE structure, and the size of fillers, which heavily influence the strength of polymer blend composites. [ABSTRACT FROM AUTHOR]

High‐density polyethylene (HDPE) and isotactic polypropylene (iPP) are widely used in industrial and residential applications due to their low cost and chemical stability, thus their recycling process can contribute to a circular economy. However, both polymers are non‐polar materials, and the incompatibility with most other materials leads to substantially inferior properties of blends. In this work, we propose a flexible compatibilization strategy to improve the compatibility of HDPE/iPP blends. Ozone is adopted to induce reactive extrusion for rapid oxidation of HDPE and chain‐branching reactions for both HDPE and HDPE/iPP blends. During extrusion process, ozone oxidizes HDPE effectively in a short time and introduces oxygen‐containing groups such as carbonyl and ester groups, which improves the hydrophilicity. The addition of trimethylolpropane triacrylate (TMPTA) could promote branching reaction and facilitate the formation of HDPE‐g‐iPP copolymers, which improved the compatibility for HDPE/iPP. As a result, the impact strength of ozone‐modified HDPE and HDPE/iPP blends increased by 22 % and 82 %, respectively, and the tensile strength also increased. This strategy would have potential applications in the field of sorting‐free and solvent‐free recycling of waste polyolefin plastics. [ABSTRACT FROM AUTHOR]

This study demonstrates a new approach to manufacturing biomimetic auricular surgical implants using melt electrowriting (MEW) technology to fabricate microfiber high‐density polyethylene (HDPE) scaffolds. An emerging filament‐driven printhead and MEW printer, termed the "MEWron", is used to enable precise control over the material extrusion process and fiber formation. By predicting the optimal extrusion conditions, continuous and uninterrupted fiber production is achieved, enabling further optimization of filament‐driven MEW fibers with a diameter of 60.5 ± 2.6 µm. As a case study, an application of microfiber HDPE fabrication is selected that comprised the design and fabrication of personalized auricular (ear) surgical implants, specifically tailored to match the unique morphology of individual patients. Patient‐specific implant models matched to the natural shape and structure of the human ear are successfully fabricated. Furthermore, the manufactured implants exhibit excellent mechanical properties, offering a 13‐fold increase in tensile stiffness compared to MEW PCL scaffolds. Overall, this research demonstrates the feasibility and potential of MEW‐based HDPE implants as a promising alternative to traditional auricular reconstruction methods, offering an alternative avenue for improved patient outcomes and enhanced aesthetic results. [ABSTRACT FROM AUTHOR]

Kinetic triplets—apparent activation energy (Ea), pre‐exponential factor (A), and the reaction model—were estimated for the thermal degradation of three primary virgin and waste plastics, as well as mixed plastics waste. Model‐free iso‐conversional FWO, KAS, Starink, Kissinger and Vyzovkin and Friedman methods were employed for the kinetic analysis. The apparent activation energy was determined by the integral methods as 206.5‐209.1 kJ mol−1 and 195.6‐198.8 kJ mol−1 for the virgin and waste high‐density polyethylene (HDPE), 211.6‐214.1 kJ mol−1 and 183.1‐186.6 kJ mol−1 for the virgin and waste polypropylene (PP), 144.0‐163.1 kJ mol−1 and 159.7‐167.1 kJ mol−1 for the virgin and waste polystyrene (PS), and 173.6‐178.9 kJ mol−1 for the mixed plastics waste respectively. Ea was found to follow the trend HDPE > PP > PS with higher values for HDPE and PP virgin samples than that for their waste and marginally smaller for the virgin PS than its waste. Degradation of all plastic samples followed Avrami‐Erofeev equation with n varying between 1.0 and 1.8. The effect of conversion on Ea suggested the degradation of both virgin and waste HDPE to consist of multiple parallel reactions while that of others to be more complex. FTIR analysis of the evolved gases was used to explain the possible reaction mechanism. A small difference between the enthalpy change and the apparent activation energy (6‐7 kJ mol−1) for all plastic samples indicated favourable pyrolysis reactions. The estimated kinetic parameters and thermodynamic properties showed the stability of different plastics as HDPE > PP > PS. [ABSTRACT FROM AUTHOR]

Vertical barrier technique is an ideal candidate for site contamination control. In practical application, the characteristic of vertical cut‐off wall is heterogeneous with permeability decreases with depth due to the increasing geostatic stress. In this study, a numerical model was established considering the coupling effect of groundwater flow and contaminant transport considering depth dependent permeability. The results showed that a heterogeneous barrier with variable permeability can reduce the breakthrough time by 63.7% compared to a fixed permeability barrier. The contaminant concentration inside the wall was up to 10 times higher than outside. Shallow leakage occurs where the horizontal migration is dominated by advection. The distribution of pore‐water pressure in the system after the installation of high‐density polyethylene (HDPE) membranes significantly reduced the shallow convective effect by reducing up to 90% pore‐water pressure. Reinforcing the vertical barrier wall using HDPE membrane can effectively prevent the shallow leakage caused by the heterogeneity. [ABSTRACT FROM AUTHOR]

Microplastic (MP) particles with sizes between 1 and 1000 µm are widely distributed worldwide. Origin, transport pathways, and fate are poorly known, as sampling, sample preparation, and detection methods are major challenges. In addition, reference materials that mimic environmental particles are lacking. The most challenging is the yield of MP particle production and the need for resource‐intensive grinding with liquid nitrogen. In this paper, a machine is designed to produce aged microplastic particles as reference material candidates with high yield. The machine is based on ultraviolet aging of a thin foil and mechanical fragmentation using clean air. An example of aging and fragmentation of high‐density polyethylene with additional physical and chemical characterization of shape, size, aging state by carbonyl index, and density is presented. [ABSTRACT FROM AUTHOR]