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Herein, silicon nitride (Si3N4) was the selected additive to be examined for its reinforcing properties on high-density polyethylene (HDPE) by exploiting techniques of the popular material extrusion (MEX) 3D printing method. Six different HDPE/Si3N4 composites with filler percentages ranging between 0.0–10.0 wt. %, having a 2.0 step, were produced initially in compounds, then in filaments, and later in the form of specimens, to be examined by a series of tests. Thermal, rheological, mechanical, structural, and morphological analyses were also performed. For comprehensive mechanical characterization, tensile, flexural, microhardness (M-H), and Charpy impacts were included. Scanning electron microscopy (SME) was used for morphological assessments and microcomputed tomography (μ-CT). Raman spectroscopy was conducted, and the elemental composition was assessed using energy-dispersive spectroscopy (EDS). The HDPE/Si3N4 composite with 6.0 wt. % was the one with an enhancing performance higher than the rest of the composites, in the majority of the mechanical metrics (more than 20% in the tensile and flexural experiment), showing a strong potential for Si3N4 as a reinforcement additive in 3D printing. This method can be easily industrialized by further exploiting the MEX 3D printing method. [ABSTRACT FROM AUTHOR]

Lignocellulose fillers, like cotton stalks, provide a stiffness that enhances the mechanical properties of composites. However, finding an appropriate filler loading for optimizing the mechanical performance of biocomposites remains a challenge, as there are disparities in the optimum filler loadings found in previous studies concerning the use of cotton stalk as a filler in biocomposite manufacturing. Therefore, the need for further investigations is of prime importance. Cotton-stalk-filler-reinforced high-density polyethylene (CS/HDPE) biocomposites were fabricated with different weight proportions (10-50 wt%) of the cotton stalk filler with particle size distributions 425 to 53 μm. The biocomposites were prepared using an extrusion process with a twin-screw extruder followed by compression molding in an electrically heated platen press. Results showed that the composite reinforced with 50 wt% filler gave the optimum values of tensile and flexural moduli. [ABSTRACT FROM AUTHOR]

In this study, we investigated the performance improvement caused by the addition of copper (Cu) nanoparticles to high-density polyethylene (HDPE) matrix material. Composite materials, with filler percentages of 0.0, 2.0, 4.0, 6.0, 8.0, and 10.0 wt% were synthesized through the material extrusion (MEX) 3D printing technique. The synthesized nanocomposite filaments were utilized for the manufacturing of specimens suitable for the experimental procedure that followed. Hence, we were able to systematically investigate their tensile, flexural, impact, and microhardness properties through various mechanical tests that were conducted according to the corresponding standards. Broadband Dielectric Spectroscopy was used to investigate the electrical/dielectric properties of the composites. Moreover, by employing means of Raman spectroscopy and thermogravimetric analysis (TGA) we were also able to further investigate their vibrational, structural, and thermal properties. Concomitantly, means of scanning electron microscopy (SEM), as well as atomic force microscopy (AFM), were used for the examination of the morphological and structural characteristics of the synthesized specimens, while energy-dispersive X-ray spectroscopy (EDS) was also performed in order to receive a more detailed picture on the structural characteristics of the various synthesized composites. The corresponding nanomaterials were also assessed for their antibacterial properties regarding Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) with the assistance of a method named screening agar well diffusion. The results showed that the mechanical properties of HDPE benefited from the utilization of Cu as a filler, as they showed a notable improvement. The specimen of HDPE/Cu 4.0 wt% was the one that presented the highest levels of reinforcement in four out of the seven tested mechanical properties (for example, it exhibited a 36.7% improvement in the flexural strength, compared to the pure matrix). At the same time, the nanocomposites were efficient against the S. aureus bacterium and less efficient against the E. coli bacterium. The use of such multi-functional, robust nanocomposites in MEX 3D printing is positively impacting applications in various fields, most notably in the defense and security sectors. The latter becomes increasingly important if one takes into account that most firearms encompass various polymeric parts that require robustness and improved mechanical properties, while at the same time keeping the risk of spreading various infectious microorganisms at a bare minimum.

In this study, we investigated the performance improvement caused by the addition of copper (Cu) nanoparticles to high-density polyethylene (HDPE) matrix material. Composite materials, with filler percentages of 0.0, 2.0, 4.0, 6.0, 8.0, and 10.0 wt% were synthesized through the material extrusion (MEX) 3D printing technique. The synthesized nanocomposite filaments were utilized for the manufacturing of specimens suitable for the experimental procedure that followed. Hence, we were able to systematically investigate their tensile, flexural, impact, and microhardness properties through various mechanical tests that were conducted according to the corresponding standards. Broadband Dielectric Spectroscopy was used to investigate the electrical/dielectric properties of the composites. Moreover, by employing means of Raman spectroscopy and thermogravimetric analysis (TGA) we were also able to further investigate their vibrational, structural, and thermal properties. Concomitantly, means of scanning electron microscopy (SEM), as well as atomic force microscopy (AFM), were used for the examination of the morphological and structural characteristics of the synthesized specimens, while energy-dispersive Xray spectroscopy (EDS) was also performed in order to receive a more detailed picture on the structural characteristics of the various synthesized composites. The corresponding nanomaterials were also assessed for their antibacterial properties regarding Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) with the assistance of a method named screening agar well diffusion. The results showed that the mechanical properties of HDPE benefited from the utilization of Cu as a filler, as they showed a notable improvement. The specimen of HDPE/Cu 4.0 wt% was the one that presented the highest levels of reinforcement in four out of the seven tested mechanical properties (for example, it exhibited a 36.7% improvement in the flexural strength, compared to the pure matrix). At the same time, the nanocomposites were efficient against the S. aureus bacterium and less efficient against the E. coli bacterium. The use of such multi-functional, robust nanocomposites in MEX 3D printing is positively impacting applications in various fields, most notably in the defense and security sectors. The latter becomes increasingly important if one takes into account that most firearms encompass various polymeric parts that require robustness and improved mechanical properties, while at the same time keeping the risk of spreading various infectious microorganisms at a bare minimum. [ABSTRACT FROM AUTHOR]

The current study was carried out to compare the hydrobiological characteristics of a selected shrimp farm in district Ratnagiri taking pond size, stocking density and culture practices into consideration. For sampling, four earthen and four high-density polyethylene (HDPE) ponds were chosen. Most of the water parameters showed significant difference with respect to different types of ponds (earthen and HDPE) viz. temperature, pH, salinity, dissolved oxygen, alkalinity and net primary productivity (NPP) of both crops (p<0.05). First crop showed significant difference among all water parameters except biochemical oxygen demand (p<0.05). Second crop (January-May) showed significant difference (p<0.05) among all parameters except hardness, ammonia, nitrite, gross primary productivity (GPP) and community respiration (CR). Phytoplankton showed significant difference (p<0.05) with respect to different types of ponds for both crops and zooplankton showed significant differences (p<0.05) only during first crop. Results indicated that high-density polyethylene (HDPE) ponds have greater consistency in water quality characteristics than earthen ponds, which could contribute to enhanced shrimp growth and survival. [ABSTRACT FROM AUTHOR]

This study investigated the influence of fiber loading and maleated polyethylene (MAPE) coupling agent on the structural, thermal, mechanical, morphological properties, and torque rheology of high-density polyethylene (HDPE) reinforced with Posidonia oceanica fiber (POF) composites. HDPE/POF composites, both with and without MAPE, were manufactured using a two-step process: composite pellets extrusion, followed by test samples injection molding with various POF loadings (0, 20, 30, and 40 wt%). HDPE/POF composites reinforced with higher loading of POF (40 wt%) exhibit superior stiffness, better crystallinity, and higher stabilized torque and mechanical energy (Em) compared to other composite formulations. Therefore, varying the POF loading leads to extrusion and injection processing variations. Furthermore, the coupling agent significantly enhances the tensile strength, ductility, impact strength, crystallinity, stabilized torque, and Em of the HDPE/POF composite. This improvement is due to the enhanced interfacial adhesion between the POF and the HDPE matrix with the addition of the MAPE, as supported by the Scanning Electron Microscopy (SEM) micrographs. [ABSTRACT FROM AUTHOR]

To obtain electrostatic charge dissipative (ESD) materials, high‐density polyethylene (HDPE) and polyaniline (PANI) blends are synthesized by the solution blending method. To prepare the blends, 0.5, 1.0, and 3.0 wt% of PANI are introduced into the HDPE matrix. The prepared blends are investigated by Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA), and scanning electron microscope (SEM). Additionally, stress–strain curves are used to examine the blends' mechanical properties. Polyaniline additions indicated an increase in thermal stability by approximately 1°C in the blends but decrease in mechanical properties. The four‐probe technique is used to determine the electrical conductivity of blends, which is found to be between 10−7 and 10−10 S/cm. The results of the conductivity values have indicated that all blends have great potential to be used as antistatic materials. For antistatic applications, the ESD performance of the blends is determined at different corona voltages. Blends achieved the antistatic requirements with a 10% cutoff decay time of approximately 2.0 s and a 1/e time of approximately 1.0 s, demonstrating quick dissipation of static charges. According to antistatic decay times, it has been shown that all blends obtained in this study can be used as antistatic material at 3 kV corona voltage. [ABSTRACT FROM AUTHOR]

In this study, titanium nitride (TiN) was selected as an additive to a high-density polyethylene (HDPE) matrix material, and four different nanocomposites were created with TiN loadings of 2.0–8.0 wt. % and a 2 wt. % increase step between them. The mixtures were made, followed by the fabrication of the respective filaments (through a thermomechanical extrusion process) and 3D-printed specimens (using the material extrusion (MEX) technique). The manufactured specimens were subjected to mechanical, thermal, rheological, structural, and morphological testing. Their results were compared with those obtained after conducting the same assessments on unfilled HDPE samples, which were used as the control samples. The mechanical response of the samples improved when correlated with that of the unfilled HDPE. The tensile strength improved by 24.3%, and the flexural strength improved by 26.5% (composite with 6.0 wt. % TiN content). The dimensional deviation and porosity of the samples were assessed with micro-computed tomography and indicated great results for porosity improvement, achieved with 6.0 wt. % TiN content in the composite. TiN has proven to be an effective filler for HDPE polymers, enabling the manufacture of parts with improved mechanical properties and quality. [ABSTRACT FROM AUTHOR]

Okra hessian cloth-reinforced high-density polyethylene (HDPE) thermoplastic composites were prepared and characterized with both raw and alkali-treated fibers. The fiber contents were optimized for both the raw Okra thermoplastic composites and the alkali-treated Okra thermoplastic composites, and the optimum value of fiber content was 55 wt%. Samples that were alkali-treated and had 55 wt% fibers were subsequently exposed to gamma radiation at doses of 2.5, 5, and 7.5 kGy. Only the sample subjected to 5 kGy showed improved performance. Treated composites exhibited higher crystallinities than the untreated samples as observed by X-Ray diffraction analysis. The rupture surface micrographs of the composites exposed to 5 kGy gamma radiation revealed more compact than others. By using Fourier transform infrared spectroscopy analysis of composites, it was found that 5 kGy dose sample showed enhanced cross-linking between Okra fibers and HDPE matrix. The irradiated composite showed less water intake than the alkali-treated samples. Composites subjected to 5 kGy gamma rays showed improved tensile strength and Young's modulus of values 66 MPa and 1925 MPa, respectively. Compared to raw and treated composites, the irradiated composites with a radiation dose of 5 kGy showed improved structural, mechanical, and thermal properties. [ABSTRACT FROM AUTHOR]

This study examined a method for de-crosslinking high-density polyethylene (HDPE) for use in heating pipes using supercritical fluids and recycling them into polyethylene. Waste crosslinked HDPE is mostly incinerated because it is a thermosetting plastic and cannot be recycled. Therefore, there is an urgent need to develop new recycling technologies for crosslinked HDPE to prevent environmental pollution. Many experiments have been conducted under various subcritical and supercritical conditions using methanol as the supercritical solvent to recycle crosslinked HDPE. Consequently, PE can be prepared via a de-crosslinking reaction. To recycle crosslinked high-density polyethylene, we conducted experiments at three rotational speeds (80, 250, and 400 rpm) of the screw under the conditions of various temperatures (300–360 ℃) by using methanol, ethanol, acetone, and water. As a result, we could prepare polyethylene with a linear structure at temperatures above 300 ℃ through the de-crosslinking reaction. This study evaluated the characteristics of recycled polyethylene based on the reaction conditions using Fourier transform infrared spectroscopy (FT-IR), gel permeation chromatography (GPC), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and tensile strength analyses. In this study, samples with the same chemical and crystal structures were prepared under all conditions. [ABSTRACT FROM AUTHOR]

The investigation of fatigue failure in polymeric materials subjected to cyclic loading holds significant importance across diverse engineering applications. Numerous variables influence material behavior, encompassing material-related factors such as composition, molecular weight, orientation, and additives, as well as external factors like applied stress magnitude (stress amplitude, dynamic stress frequency and mean stress), and operating temperature. This paper presents an experimental exploration into the impact of loading parameters—mean stress, stress amplitude, and dynamic stress frequency—on the failure modes of two thermoplastic materials: high-density polyethylene (HDPE) and polyvinyl chloride (PVC). The study begins with an assessment of the mechanical and physical properties of the materials, followed by the design and manufacturing of a specialized uniaxial fatigue test rig. Tensile–tensile fatigue tests incorporating positive mean stress are conducted, evaluating the influence of altering stress amplitude and frequency on fatigue life and failure mode. The outcomes reveal that HDPE primarily experiences thermal and creep failure modes, with a lack of observed fatigue failure. Conversely, PVC specimens manifest three distinct failure modes: ductile, creep, and fatigue, with the type of failure contingent upon loading parameters. These findings offer significant insights into the various fatigue failure modes and contribute to an enhanced comprehension of the intricate interplay between loading dynamics and failure modes in polymeric materials. [ABSTRACT FROM AUTHOR]

This research employed Monte Carlo simulation as a computational technique to investigate the copolymerization of ethylene and 1-butene in the presence of hydrogen, utilizing slurry and solution processes. A dual-site metallocene catalyst was utilized to synthesize high-density polyethylene (HDPE) with a bimodal molecular weight distribution (MWD). The solution process accelerated copolymerization rates and hydrogen transfer compared to the slurry. Furthermore, under equivalent conditions, the solution process exhibited a twofold higher level of 1-butene incorporation into copolymer chains. Elevating 1-butene partial pressure by 50% increased weight average molecular weight ($\bar{M}_w$ M ¯ w ) of copolymers by 15% in solution process and 5% in slurry process. Increasing 1-butene partial pressure expanded and shifted the bimodal distribution towards higher molecular weights in both processes. Elevated hydrogen partial pressure enhanced peak heights and shifted towards lower molecular weights, with the slurry process showing stronger effects. The solution process had a range of short-chain branching per 1000 carbon atoms (SCB/1000C) (15-40), approximately twice as large as the slurry process. The slurry process resulted in more regular chains with higher crystallinity (68.7%) compared to the solution process (66.4%). [ABSTRACT FROM AUTHOR]

Herein, silicon nitride (Si3N4) was the selected additive to be examined for its reinforcing properties on high-density polyethylene (HDPE) by exploiting techniques of the popular material extrusion (MEX) 3D printing method. Six different HDPE/Si3N4 composites with filler percentages ranging between 0.0–10.0 wt. %, having a 2.0 step, were produced initially in compounds, then in filaments, and later in the form of specimens, to be examined by a series of tests. Thermal, rheological, mechanical, structural, and morphological analyses were also performed. For comprehensive mechanical characterization, tensile, flexural, microhardness (M-H), and Charpy impacts were included. Scanning electron microscopy (SME) was used for morphological assessments and microcomputed tomography (μ-CT). Raman spectroscopy was conducted, and the elemental composition was assessed using energy-dispersive spectroscopy (EDS). The HDPE/Si3N4 composite with 6.0 wt. % was the one with an enhancing performance higher than the rest of the composites, in the majority of the mechanical metrics (more than 20% in the tensile and flexural experiment), showing a strong potential for Si3N4 as a reinforcement additive in 3D printing. This method can be easily industrialized by further exploiting the MEX 3D printing method.

The annual production of plastic waste worldwide has doubled in just two decades, with approximately 390 million tonnes of plastic waste now being generated. In this context, the construction industry must move towards the development of new, more sustainable materials made under circular economy criteria. In this work, a physico-mechanical characterisation of gypsum composites with the incorporation of high-density polyethylene (HDPE) waste, replacing 2–4–6–8–10% by volume of the original raw material, has been conducted. The results show how the incorporation of these plastic wastes improves the water resistance of the gypsum material without additions, as well as producing a decrease in thermal conductivity and greater resistance to impact. On the other hand, it has been found that, as the percentage of recycled raw material added increases, the mechanical resistance to bending and compression decreases, leading to fracture due to a lack of cohesion between the matrix and the waste. Nevertheless, in all the cases studied, mechanical strengths higher than those established by the EN 13279-2 standard were obtained. Thus, the results confirm the viability of these secondary raw materials to be used in the development of new products for sustainable building, especially in the design of prefabricated panels for false ceilings. [ABSTRACT FROM AUTHOR]

Catalytic pyrolysis of waste HDPE and LDPE polyethylene was successfully carried out using a silica-alumina catalyst at 450 °C under N2 atmosphere. The synthesized silica-alumina is mesoporous and shows type IV isotherm. Thermal pyrolysis (without any catalyst) provided 47% waxlike hydrocarbons at 485 °C. On the other hand, more than 80% liquid yield was achieved using silica-alumina catalysts from waste HDPE and LDPE. The highest liquid yield was obtained from LDPE (87.69%) than HDPE (83.25%) at a catalyst-to-plastic ratio of 1:25. The 1H NMR shows that the liquid product does not contain any aromatic compound. The GCMS, 1H NMR, and FTIR confirmed that the liquid contains linear and branched alkanes and alkenes. [ABSTRACT FROM AUTHOR]

This study investigated the influence of fiber loading and maleated polyethylene (MAPE) coupling agent on the structural, thermal, mechanical, morphological properties, and torque rheology of high-density polyethylene (HDPE) reinforced with Posidonia oceanica fiber (POF) composites. HDPE/POF composites, both with and without MAPE, were manufactured using a two-step process: composite pellets extrusion, followed by test samples injection molding with various POF loadings (0, 20, 30, and 40 wt%). HDPE/POF composites reinforced with higher loading of POF (40 wt%) exhibit superior stiffness, better crystallinity, and higher stabilized torque and mechanical energy (Em) compared to other composite formulations. Therefore, varying the POF loading leads to extrusion and injection processing variations. Furthermore, the coupling agent significantly enhances the tensile strength, ductility, impact strength, crystallinity, stabilized torque, and Em of the HDPE/POF composite. This improvement is due to the enhanced interfacial adhesion between the POF and the HDPE matrix with the addition of the MAPE, as supported by the Scanning Electron Microscopy (SEM) micrographs.

In this study, titanium nitride (TiN) was selected as an additive to a high-density polyethylene (HDPE) matrix material, and four different nanocomposites were created with TiN loadings of 2.0–8.0 wt. % and a 2 wt. % increase step between them. The mixtures were made, followed by the fabrication of the respective filaments (through a thermomechanical extrusion process) and 3D-printed specimens (using the material extrusion (MEX) technique). The manufactured specimens were subjected to mechanical, thermal, rheological, structural, and morphological testing. Their results were compared with those obtained after conducting the same assessments on unfilled HDPE samples, which were used as the control samples. The mechanical response of the samples improved when correlated with that of the unfilled HDPE. The tensile strength improved by 24.3%, and the flexural strength improved by 26.5% (composite with 6.0 wt. % TiN content). The dimensional deviation and porosity of the samples were assessed with micro-computed tomography and indicated great results for porosity improvement, achieved with 6.0 wt. % TiN content in the composite. TiN has proven to be an effective filler for HDPE polymers, enabling the manufacture of parts with improved mechanical properties and quality.

Fossil fuel consumption has progressively increased alongside global population growth, representing the predominant energy consumption pattern for humanity. Unfortunately, this persistent reliance on fossil fuels has resulted in a substantial surge in pollution emissions, exerting a detrimental influence on the delicate ecological balance. Therefore, it is imperative to find new renewable energy sources to replace fossil fuels. Solar energy is a clean energy source and has become the most preferred option for human day-to-day needs. Since the construction of the world's first floating photovoltaic power station, humanity has been continuously advancing the technology of power generation by floating photovoltaics. This review comprehensively elucidates the progression of offshore photovoltaic technology and illustrates the composition of the floating photovoltaic system. Each section meticulously contrasts the advantages and drawbacks of various photovoltaic systems. In addition, an in-depth analysis of the offshore photovoltaic application potentials is conducted based on fundamental theories, thereby offering valuable insights for future research. Finally, an encompassing summary of the potential challenges associated with deep-sea floating photovoltaic systems is presented. [ABSTRACT FROM AUTHOR]

The tribological properties of three-dimensional (3D) printed polymeric composites are often less explored due to the complexity involved related to their softness, poor mechanical properties, and lower thermal conductivities. Keeping this in view, this work reports the influence of carbon nanotubes (CNTs) on the tribological properties of high-density polyethylene (HDPE) composites. Fused deposition modeling was adopted to develop the composites with varying CNT contents from 0.5 wt% to 2 wt%. The tribological properties were studied by subjecting them to friction-on-wear test using a pin-on-disc setup. The tests were conducted with varying applied loads (5 to 20 N) and sliding speeds (0.262 to 1.048 m/s). A scanning electron microscope (SEM) was employed to study the morphology of the filaments and to analyze the worn surfaces after testing. The printed composite parts displayed a good dispersion of CNTs, showed a good print quality, and were free from warpage or shrinkage defects. With the increase in load and sliding velocity, both the wear rate and coefficient of friction of all the developed samples tend to increase. Out of all the developed samples, some showed poor wear resistance, while composites with the highest CNT contents of 2 wt% showed significant resistance to material loss, which is attributed to the reduced contact area and the CNT acting as an anchor to prevent the polymer chain from being detached. The worn surface analysis revealed adhesive wear as the dominant mechanism for pure HDPE, and abrasive wear as the primary mechanism for HDPE composites. Overall, this work showed that CNTs can be used as an effective filler for reducing the friction coefficient and increasing the wear resistance. [ABSTRACT FROM AUTHOR]

When properly compatibilized, the blending of polyethylene (PE) and polyamide (PA) leads to materials that combine low prices, suitable processability, impact resistance, and attractive mechanical properties. Moreover, the possibility of using these polymers without prior separation may be a suitable opportunity for their recycling. In this work, the use of an epoxidized waste vegetable oil (EWVO) was investigated as a green compatibilizer precursor (CP) for the reactive blending of a high-density PE (HDPE) with a polyamide-6 (PA6). EWVO was synthesized from waste vegetable cooking oil (WVO) using ion-exchange resin (Amberlite) as a heterogeneous catalyst. HDPE/PA6 blends were produced with different weight ratios (25/75, 75/25, 85/15) and amounts of EWVO (1, 2, 5 phr). Samples with WVO or a commercial fossil-based CP were also prepared for comparison. All the blends were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), rheology, and mechanical tests. In the case of HDPE/PA6 75/25 and 85/15 blends, the addition of EWVO at 2 phr showed a satisfactory compatibilizing effect, thus yielding a material with improved mechanical properties with respect to the blend without compatibilizer. On the contrary, the HDPE/PA6 25/75 ratio yielded a material with a high degree of crosslinking that could not be further processed or characterized. In conclusion, the results showed that EWVO had a suitable compatibilizing effect in HDPE/PA6 blends with high HDPE content, while it resulted in unsuitable for blends with high content of PA6. [ABSTRACT FROM AUTHOR]

Ultra-high molecular weight polyethylene (UHMWPE) acquires excellent properties while possessing poor processability. Blending low molecular weight polyethylene disentangles the molecular chain of UHMWPE and improves its processability, improving fiber productivity. In the present study, UHMWPE and its HDPE-blended fibers were produced by a high-temperature electrospinning process, and the effect of HDPE content on fiber properties was investigated in depth. Analysis of fiber surface morphology revealed the formation of uniformly distributed nano- to microscopic pores/pits, wrinkles, and grooves on the surface of blended fibers, unlike neat UHMWPE fibers containing irregular surface bulges and pits. It suggested that the blending of HDPE affected the surface topography and the thermal and mechanical properties of electrospun fibers. The tensile strength and Young's modulus of UHMWPE fiber improved by 142 and 102% at a 67:33 mass ratio of UHMWPE and HDPE and by 84 and 132% in the case of a 50:50 composition ratio, respectively. [ABSTRACT FROM AUTHOR]

The morphology of virgin reactor powder (RP) of high-density polyethylene (HDPE) with MW = 160,000 g/mol was investigated using DSC, SEM, SAXS, and WAXS methods. The morphological SEM analysis showed that the main morphological units of RP are macro- and micro-shish-kebab structures with significantly different geometric dimensions, as well as individual lamellae of folded chain crystals. A quantitative analysis of an asymmetric SAXS reflection made it possible to reveal the presence of several periodic morphoses in the RP with long periods ranging from 20 nm to 60 nm, and to correlate them with the observed powder morphology. According to the DSC crystallinity data, the thickness of the lamellae in each long period was estimated. Their surface energy was calculated in the framework of the Gibbs—Thompson theory. The presence of regular and irregular folds on the surface of different shish-kebab lamellae was discussed. The percentage of identified morphoses in the RP was calculated. It has been suggested that the specific structure of HDPE RP is due to the peculiarity of polymer crystallization during suspension synthesis in a quasi-stationary regime, in which local overheating and inhomogeneous distribution of shear stresses in a chemical reactor are possible. [ABSTRACT FROM AUTHOR]

A new melt mixing and in‐situ exfoliation method based on the synergy of multi‐source pulsating flow and phase transition (MSPFPT) was reported. The corresponding device was also developed, and the structure and mixing process of the mixer were introduced in detail. High‐density polyethylene (HDPE)/expanded graphite (EG) composites were prepared via this new mixer, and microstructure and thermal properties of the composites were comprehensively investigated. Morphological analyses demonstrate that MSPFPT method promotes the efficient exfoliation and uniform dispersion of EG. The well‐exfoliated EG layers form more thermal conductive paths in the composites prepared by MSPFPT, increasing thermal conductivity from 0.47 of pure HDPE to 1.16 W/(m·K) with 9 wt.% EG. The crystallinity degree of HDPE is increased by 11.1%. The increment of crystallinity reduces phonon scattering, which further confirms that MSPFPT method can significantly improve the thermal performance. The research provides a practical strategy for fabricating high‐performance composites filled with layered fillers. [ABSTRACT FROM AUTHOR]

The exponential increase in production and consumption of plastic has led to accumulation of plastic waste in the environment, resulting in detrimental impacts on human health and the natural environment. Plastic pollution not only stems from discarded plastics but also from the chemicals released during plastic production and decomposition. Various waste management strategies exist for plastic waste, including landfilling, recycling, conversion to liquid fuel, and upcycling. Landfilling, which is a prevalent method, contributes to long-term environmental degradation. Recycling is practiced worldwide, but its percentage remains low, particularly in regions like South Asia. Conversion to liquid fuel through pyrolysis has been explored as a viable solution, although commercialization faces challenges. Upcycling, which involves depolymerization and repolymerization, offers an avenue to recycle plastic waste into valuable chemicals, specifically focusing on high-density polyethylene (HDPE) and low-density polyethylene (LDPE). Currently, HDPE and LDPE make up 36% of all plastic trash by mass, but they have the potential to account for far more. When plastic waste is incinerated or buried in the earth, it generates carbon dioxide and heat, which pollute our environment. Depolymerization is a way to chemically recycle plastic waste into monomers, but this process requires a large amount of energy. Controlled partial depolymerization can transform PE into new, high-quality products at a temperature of more than 400 °C with or without a catalyst. In this study, we provide a novel approach for the conversion of plastic waste, particularly HDPE and LDPE, into valuable alkyl aromatics. By implementing controlled partial depolymerization, we propose a plant design capable of transforming plastic waste into high-quality chemicals. The design aims to optimize energy consumption, process efficiency, and product quality. The research findings contribute to sustainable plastic waste management and the reduction in environmental pollution caused by plastic waste. [ABSTRACT FROM AUTHOR]

The utilization of acidic aggregates in hot-mix asphalt (HMA) is often inevitable due to the limited supply of locally available aggregates, posing a potential threat of moisture damage to asphalt pavements. In this regard, the use of urban waste plastic to coat the low-quality aggregates is a promising way to improve the moisture resistance. This study fundamentally evaluated the compatibility between asphalt and plastic-coated aggregate by measuring surface energy, and for the first time compared the effects of different types of waste plastic including high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene terephthalate (PET), polyvinyl chloride (PVC), and polypropylene (PP). The plastic-coating significantly altered the chemistry of aggregate surface by increasing the nonpolar components and reducing the polar components. Such changes remarkably increased the dry adhesion energy between asphalt and aggregate and enhanced the wettability of aggregate. For the acidic aggregates, the polymeric treatment could decrease the value of wet adhesive, which indicated the debonding tendency in the presence of water was reduced. Finally, the energy ratios of the asphalt-aggregate combinations significantly increased by the surface pretreatment, which proved the effect of waste plastic coating on improving the moisture damage resistance of asphalt mixtures. By comparison, the HDPE coating was the most effective way to enhance the compatibility with asphalt, followed by PP and LDPE coatings. The PVC and PET coatings were investigated as the least effective way. This study cannot only contribute to the potential large-scale utilization of waste plastic but also remove the obstacles of using large quantities of acidic natural aggregate in asphalt pavements. [ABSTRACT FROM AUTHOR]

Ultra-high molecular weight polyethylene (UHMWPE) has extremely outstanding mechanical properties and wear resistance, but its melt flowability is too poor, resulting in poor processability. In this work, high-density polyethylene (HDPE) was melt-blended with UHMWPE to promote the flowability of UHMWPE melt. We investigated the effects of UHMWPE and HDPE contents on the rheological behavior, crystallization behavior, mechanical properties, and wear resistance of UHMWPE/HDPE blends. The results show that when the content ratio of UHMWPE and HDPE is 50:50, the UHMWPE/HDPE blend exhibits the best mechanical properties and wear resistance, as well as good processability. The tensile strength and elongation at break of 50UHMWPE/50HDPE are as high as 52.12 MPa and 700%, respectively, and the mass loss after erosion is only 0.04 g, which is far lower than the mass loss of pure HDPE (0.267g). Therefore, UHMWPE/HDPE blends with outstanding wear resistance and mechanical properties are expected to achieve large-scale industrial applications. [ABSTRACT FROM AUTHOR]

This research investigated the effect of high-density polyethylene (HDPE) from various sources on the damage-related behaviour of bitumen in the intermediate- and high-temperature domains. For this purpose, base bitumen was modified by the mass fraction of 1.5% of HDPE from post-industrial recycled pellets and from post-consumer recycled flakes. The experimental programme consisted of the multiple stress creep and recovery from 40 to 70°C and of the linear shear strain amplitude sweep at 10, 20, and 30°C. The HDPE significantly reduced the non-recoverable creep compliance but increased the elastic recovery. The post-industrial HDPE-modified bitumen exhibited superior resistance to permanent deformation, with its crystallinity recognised as the most important factor. This reduced the susceptibility of its behaviour to shear stress and temperature. The HDPE-modified bitumen had a considerably longer fatigue life, but its sensitivity to premature failure at low temperatures and the conspicuously high brittleness represented the main issue for further improvements. [ABSTRACT FROM AUTHOR]

Failure of high-density polyethylene (HDPE) aboveground storage tanks (ASTs) causes numerous environmental, ecological, and economic problems. Therefore, it is necessary to routinely inspect the integrity of ASTs to identify the potential defects and act before a catastrophic failure happens. This study investigated the feasibility of using infrared thermography (IRT) for routine HDPE AST inspections and how weathering impacts the properties of HDPE. Moreover, the factors affecting the IRT's accuracy for defect detection were researched, and it was attempted to determine the minimum levels of defect detection for each weather circumstance. This study investigated the potential areas for tank failure for close inspection. Results showed that IRT is efficient in detecting shallow defects within the outer half of the wall. The smallest detectable defect size was 2.8 mm, which varied in different measurements depending on the interaction of sample geometry, initial thermal gradient, and defect location. [ABSTRACT FROM AUTHOR]

High-density polyethylene (HDPE) is one of the most commonly used materials for manufacturing pipelines. In this paper, the deformation behavior of HDPE materials under uniaxial tensile stress was investigated by employing uniaxial tensile tests and macroscale/mesoscale morphology analysis. The experimental results indicated that the stress–strain relationship of HDPE is nonlinear, and the ductile fracture characteristics of necking and local failure appear in the sample after the engineering strain reaches 35%. Therefore, for the first time, a hyperelastoplastic constitutive model that describes the elasticity by the Marlow model and combined the isotropic plasticity-ductility damage correction is established, and a corresponding numerical approach is proposed. The simulation scheme was implemented in finite-element software, and the mechanical responses of HDPE under uniaxial tensile and bending loads were predicted. Obtained calculations were relatively consistent with experimental observations. Hence, the proposed model and approach have a good simulation effect on the mechanical properties of HDPE and can be employed for the process prediction of such materials. This study is beneficial to the in-depth understanding of the hyperelastoplasticity and failure mechanism of HDPE and provides ideas for the deformation and failure study of other polymer materials. [ABSTRACT FROM AUTHOR]

The annual production of plastic waste worldwide has doubled in just two decades, with approximately 390 million tonnes of plastic waste now being generated. In this context, the construction industry must move towards the development of new, more sustainable materials made under circular economy criteria. In this work, a physico-mechanical characterisation of gypsum composites with the incorporation of high-density polyethylene (HDPE) waste, replacing 2–4–6–8–10% by volume of the original raw material, has been conducted. The results show how the incorporation of these plastic wastes improves the water resistance of the gypsum material without additions, as well as producing a decrease in thermal conductivity and greater resistance to impact. On the other hand, it has been found that, as the percentage of recycled raw material added increases, the mechanical resistance to bending and compression decreases, leading to fracture due to a lack of cohesion between the matrix and the waste. Nevertheless, in all the cases studied, mechanical strengths higher than those established by the EN 13279-2 standard were obtained. Thus, the results confirm the viability of these secondary raw materials to be used in the development of new products for sustainable building, especially in the design of prefabricated panels for false ceilings.

High-density polyethylene (HDPE) is a well-established thermoplastic; however, with concerns about the fate of plastics at end-of-life, there is a growing interest in strategies to utilize recycled HDPE (rHDPE) in place of virgin HDPE (vHDPE). This study investigated the tensile properties of rHDPE/talc blends (0, 20, 28, and 38 wt% talc) and adequate talc dispersion was found in the blends using SEM imaging. Increases in tensile strength (up to 20.4%), elastic nominal stiffness (up to 93.5%), and a decrease in nominal yield strain (up to 50%) were observed for rHDPE with increasing talc content. The trends observed indicate that rHDPE could be a viable alternative/supplement to vHDPE for use in large volume structural applications. If talc filler particle dispersion can be well monitored, the rHDPE/talc blends have significant potential to be used and hence reduce the amount of virgin material needed; however, additional properties should be further explored.

The demand for high-performance asphalt pavements has been increasing in recent years due to increased traffic volume, automobile size and weight, and rising temperatures due to climate change. It is necessary to modify the bitumen to achieve long-life high-performance pavements in many cases. Consequently, polymers obtained from plastic wastes emerged as a modifier to enhance the bitumen properties. Polymers offer a number of advantages. Polymers such as polyethylene (PE) or polypropylene (PP) offer a number of advantages when used as binder modifier. Using PE or PP in infrastructure projects can be an innovative method to reduce the environmental damage of these nonbiodegradable wastes and the high cost of recycling these wastes. Therefore, this paper extensively investigates the experimental studies carried out by many researchers to evaluate polymer-modified binders' properties as an alternative for pure bitumen in asphalt mixtures under different percentages and production processes. The main goal is to establish a better understanding of the engineering properties of polyethylene-modified asphalt mixtures and ultimately argue that waste polyethylene has a viable use as a modifier for asphalt binders. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel technique for the inspection of high-density polyethylene (HDPE) pipes using ultrasonic sensors, signal processing, and deep neural networks (DNNs). Specifically, we propose a technique that detects whether there is a diversion on a pipe or not. The proposed model transmits ultrasound signals through a pipe using a custom-designed array of piezoelectric transmitters and receivers. We propose to use the Zadoff–Chu sequence to modulate the input signals, then utilize its correlation properties to estimate the pipe channel response. The processed signal is then fed to a DNN that extracts the features and decides whether there is a diversion or not. The proposed technique demonstrates an average classification accuracy of 90.3 % (when one sensor is used) and 99.6 % (when two sensors are used) on 3 4 inch pipes. The technique can be readily generalized for pipes of different diameters and materials. [ABSTRACT FROM AUTHOR]

This paper presents the effect of the addition of fillers such as aluminum hydroxide or montmorillonite on the structure and properties of polymers such as high-density polyethylene (HDPE) and polybutylene terephthalate (PBT). Both types of specimens were obtained by injection molding. X-ray diffraction examinations were performed on the materials obtained to determine the effect of the addition of the fillers used on the degree of crystallinity of the composites. The density and hardness of the composites were evaluated, and the static tensile test and the analysis of the structure parameters using atomic force microscopy (AFM) were also carried out. It was shown that the addition of powder fillers to polymers such as high-density polyethylene and polybutylene terephthalate affects the structure parameters such as surface roughness, mean grain size, anisotropy ratio, fractal dimension, the corner frequency of the composites, and mechanical properties such as Young's pseudo-modulus, average adhesion force, hardness, and tensile strength. [ABSTRACT FROM AUTHOR]

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Fossil fuel consumption has progressively increased alongside global population growth, representing the predominant energy consumption pattern for humanity. Unfortunately, this persistent reliance on fossil fuels has resulted in a substantial surge in pollution emissions, exerting a detrimental influence on the delicate ecological balance. Therefore, it is imperative to find new renewable energy sources to replace fossil fuels. Solar energy is a clean energy source and has become the most preferred option for human day-to-day needs. Since the construction of the world’s first floating photovoltaic power station, humanity has been continuously advancing the technology of power generation by floating photovoltaics. This review comprehensively elucidates the progression of offshore photovoltaic technology and illustrates the composition of the floating photovoltaic system. Each section meticulously contrasts the advantages and drawbacks of various photovoltaic systems. In addition, an in-depth analysis of the offshore photovoltaic application potentials is conducted based on fundamental theories, thereby offering valuable insights for future research. Finally, an encompassing summary of the potential challenges associated with deep-sea floating photovoltaic systems is presented.

When properly compatibilized, the blending of polyethylene (PE) and polyamide (PA) leads to materials that combine low prices, suitable processability, impact resistance, and attractive mechanical properties. Moreover, the possibility of using these polymers without prior separation may be a suitable opportunity for their recycling. In this work, the use of an epoxidized waste vegetable oil (EWVO) was investigated as a green compatibilizer precursor (CP) for the reactive blending of a high-density PE (HDPE) with a polyamide-6 (PA6). EWVO was synthesized from waste vegetable cooking oil (WVO) using ion-exchange resin (Amberlite) as a heterogeneous catalyst. HDPE/PA6 blends were produced with different weight ratios (25/75, 75/25, 85/15) and amounts of EWVO (1, 2, 5 phr). Samples with WVO or a commercial fossil-based CP were also prepared for comparison. All the blends were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), rheology, and mechanical tests. In the case of HDPE/PA6 75/25 and 85/15 blends, the addition of EWVO at 2 phr showed a satisfactory compatibilizing effect, thus yielding a material with improved mechanical properties with respect to the blend without compatibilizer. On the contrary, the HDPE/PA6 25/75 ratio yielded a material with a high degree of crosslinking that could not be further processed or characterized. In conclusion, the results showed that EWVO had a suitable compatibilizing effect in HDPE/PA6 blends with high HDPE content, while it resulted in unsuitable for blends with high content of PA6.

The morphology of virgin reactor powder (RP) of high-density polyethylene (HDPE) with MW = 160,000 g/mol was investigated using DSC, SEM, SAXS, and WAXS methods. The morphological SEM analysis showed that the main morphological units of RP are macro- and micro-shish-kebab structures with significantly different geometric dimensions, as well as individual lamellae of folded chain crystals. A quantitative analysis of an asymmetric SAXS reflection made it possible to reveal the presence of several periodic morphoses in the RP with long periods ranging from 20 nm to 60 nm, and to correlate them with the observed powder morphology. According to the DSC crystallinity data, the thickness of the lamellae in each long period was estimated. Their surface energy was calculated in the framework of the Gibbs—Thompson theory. The presence of regular and irregular folds on the surface of different shish-kebab lamellae was discussed. The percentage of identified morphoses in the RP was calculated. It has been suggested that the specific structure of HDPE RP is due to the peculiarity of polymer crystallization during suspension synthesis in a quasi-stationary regime, in which local overheating and inhomogeneous distribution of shear stresses in a chemical reactor are possible.

The subject of this study is the application of the piezoelectric direct discharge (PDD) operated with nitrogen to control the surface free energy (SFE) of polymers. The activation area, defined as the area of the zone reaching the SFE of 58 mN/m for high-density polyethylene (HDPE) and poly (methyl methacrylate) (PMMA), is characterized. For HDPE, the activation area was characterized as a function of the distance from 1 to 16 mm, the nitrogen flow from 5 to 20 SLM, and the treatment time from 1 to 32 s. For larger distances, where SFE does not exceed 58 mN/m, the water contact angle is evaluated. The activation area for nitrogen PDD is typically a factor of 3 higher than for air with all other conditions the same. A maximum static activation area of 15 cm2 is reached. The plasma treatment of lens panels made of PMMA is presented as application example.

High-density polyethylene (HDPE) is considered an eco-friendly material for boat construction worldwide. However, managing thermal distortion in HDPE welding is challenging, impacting productivity. Traditional steel shipbuilding has established methods to predict welding-induced thermal distortion, but HDPE lacks comprehensive studies and standards. This research explores applying the elastic Finite Element (FE) approach, commonly used in steel structures, to HDPE welding. The elastic FE approach simplifies complex welding simulations, enabling its use in large structures like ship hulls. Our research assesses whether HDPE welded specimens exhibit similar distortion patterns to conventional welded structures and whether consistent parameters yield similar thermal distortion. Alignment between our FE analysis, based on specimen data, and experimental results validates the feasibility of using the elastic FE approach to predict HDPE thermal distortion. This study suggests it as a practical method to enhance HDPE boat manufacturing productivity.

This research studied the process of manufacturing horizontal groundwater storage tanks from steel reinforced polyethylene corrugated pipes. The surfaces, galvanized flat carbon steel and polyethylene, are bonded using an extrusion process. Welding was done using a plastic electro-fusion welding method. The tank was tested for mechanical integrity and leakage to determine its feasibility in an actual application. Testing showed no leakage. A contamination test showed that water stored in the tank contained dissolved substances, but in low enough concentrations that the water passed the testing criteria. The tank deformation test showed that the maximum deformation of the tank in an on-site compression test was less than 7 mm for all cases involving static and dynamic loading of 24 tonnes, according to industrial standards. The results show that it is possible to use an underground steel reinforced polyethylene corrugated water tank with plastic welding in real-world applications.

Friction stir welding (FSW) of polymeric materials has recently attracted significant attention. Herein, we present the effect of the tool pin profile on the FSW of high-density polyethylene (HDPE) joints through joint experimental analysis and thermomechanical simulations. For analysis of pin profile effects on the thermomechanical properties of HDPE joints, frustum (FPT), cubic (CPT), and triangular (TPT) pin shapes were selected in this study. This research investigated the heat generation of the parts of the different tools as well as heat flux (internal and surface). The results revealed that the heat generation in pins with more edges (cubic (96 °C) and triangular (94 °C)) was greater than in pins with a smooth shape (frustum (91 °C)). The higher heat generation caused the heat flux on the surface of the HDPE from the cubic pin profile to be greater than for other joints. Due to the properties of HDPE, higher heat generation caused higher material velocity in the stirring zone, where the velocity of the materials in TPT, CPT, and FPT pins were 0.41 m/s, 0.42 m/s, and 0.4 m/s, respectively. The simulation results show sharp-edged pins, such as triangular and cubic, lead to over-stirring action and internal voids formed along the joint line. Furthermore, the simulation results indicated that the size of the stirred zones (SZs) of the FPT, TPT, and CPT samples were 17 mm2, 19 mm2, and 21 mm2, respectively, which is around three times the corresponding values in the HAZ. [ABSTRACT FROM AUTHOR]

Pyrolysis is considered as a promising direction in the processing of plastic waste for energy production and as a clean technology that meets energy security objectives. The main products obtained in the pyrolysis process are gas, liquid (condensable pyrolysis fuel), and coal (solid component). The influence of the process temperature and catalysts on the yield of pyrolysis fractions is analyzed. This study indicates that it is important not only to solve the problem of plastic waste, but also to develop fuels based on the pyrolysis of plastics. [ABSTRACT FROM AUTHOR]

The scope of this work was to develop novel polymer composites via melt extrusion and 3D printing, incorporating High-Density Polyethylene filled with zinc oxide particles in various wt. percentages. For each case scenario, a filament of approximately 1.75 mm in diameter was fabricated. Samples for tensile and flexural testing were fabricated with 3D printing. They were then evaluated for their mechanical response according to ASTM standards. According to the documented testing data, the filler increases the mechanical strength of pure HDPE at specific filler concentrations. The highest values reported were a 54.6% increase in the flexural strength with HDPE/ZnO 0.5 wt.% and a 53.8% increase in the tensile strength with 10 wt.% ZnO loading in the composite. Scanning Electron Microscopy (SEM), Raman, and thermal characterization techniques were used. The experimental findings were evaluated in other research areas where they were applicable. [ABSTRACT FROM AUTHOR]

The exponential increase in production and consumption of plastic has led to accumulation of plastic waste in the environment, resulting in detrimental impacts on human health and the natural environment. Plastic pollution not only stems from discarded plastics but also from the chemicals released during plastic production and decomposition. Various waste management strategies exist for plastic waste, including landfilling, recycling, conversion to liquid fuel, and upcycling. Landfilling, which is a prevalent method, contributes to long-term environmental degradation. Recycling is practiced worldwide, but its percentage remains low, particularly in regions like South Asia. Conversion to liquid fuel through pyrolysis has been explored as a viable solution, although commercialization faces challenges. Upcycling, which involves depolymerization and repolymerization, offers an avenue to recycle plastic waste into valuable chemicals, specifically focusing on high-density polyethylene (HDPE) and low-density polyethylene (LDPE). Currently, HDPE and LDPE make up 36% of all plastic trash by mass, but they have the potential to account for far more. When plastic waste is incinerated or buried in the earth, it generates carbon dioxide and heat, which pollute our environment. Depolymerization is a way to chemically recycle plastic waste into monomers, but this process requires a large amount of energy. Controlled partial depolymerization can transform PE into new, high-quality products at a temperature of more than 400 °C with or without a catalyst. In this study, we provide a novel approach for the conversion of plastic waste, particularly HDPE and LDPE, into valuable alkyl aromatics. By implementing controlled partial depolymerization, we propose a plant design capable of transforming plastic waste into high-quality chemicals. The design aims to optimize energy consumption, process efficiency, and product quality. The research findings contribute to sustainable plastic waste management and the reduction in environmental pollution caused by plastic waste.