Recycled High Density Polyethylene Research Articles

Migration of volatile substances from recycled high density polyethylene to milk products

Plastic recycling is the main solution to reduce the plastic waste. High-density polyethylene has not been recycled yet successfully as food contact material due to the amount of chemicals present in post-consumer material together with its high chemical sorption capacity. The migration of two post-consumer recycled HDPE milk bottles were studied to both 50 % ethanol as food simulant and real food (one type skimmed milk and two plant base beverages (soy milk and horchata). Firstly, a headspace-solid phase extraction-gas chromatography mass spectrometry method was developed and optimized to analyze these milky samples. After exposure, 53 compounds were identified and among them several additives, NIAS such as 2,5-cyclohexadiene-1,4-dione, 2,6-bis(1,1-dimethylethyl), 2,4-di-tert-butylphenol and 7,9-di-tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione, degradation products of antioxidant compounds as well as several residues from cleaning products, detergents and flavoring agents were found. Finally, the risk assessment was applied and it was found that five compounds did not comply after migration to 50 % ethanol.

Recycled high-density polyethylene plastic reinforced with ilmenite as a sustainable radiation shielding material.

In this work, recycled high-density polyethylene plastic (r-HDPE) reinforced with ilmenite mineral (Ilm) in different ratios (0, 15, 30, and 45 wt%) as a sustainable and flexible radiation shielding material was manufactured using the melt blending method. XRD patterns and FTIR spectra demonstrated that the polymer composite sheets were successfully developed. The morphology and elemental composition were addressed using SEM images and EDX spectra. Moreover, the mechanical characteristics of the prepared sheets were also studied. The gamma-ray attenuation characteristics for established r-HDPE + x% Ilm composite sheets were theoretically computed between 0.015 and 15 MeV using Phy-X/PSD software. Also, the mass attenuation coefficients have been compared to their values by the WinXCOM program. It is also shown that the shielding performance of the r-HDPE + 45% Ilm composite sheet is significantly greater than that of r-HDPE. As a result, the ilmenite-incorporated recycled high-density polyethylene sheets are suited for medical and industrial radiation shielding applications.

Stress-Crack Resistance and Life Prediction of Corrugated Recycled and Virgin HDPE Pipes Used in Road Drainage Systems in Quebec, Canada

Stress-Crack Resistance and Life Prediction of Corrugated Recycled and Virgin HDPE Pipes Used in Road Drainage Systems in Quebec, Canada

Blending Recycled High-Density Polyethylene HDPE (rHDPE) with Virgin (vHDPE) as an Effective Approach to Improve the Mechanical Properties

The mechanical properties of virgin/recycled high-density polyethylene (HDPE) blends over the complete concentration range was thoroughly investigated in this work. In particular, a focus was made on the long-term properties via mechanical fatigue. Two different mixing methods, namely powder mixing (dry blending) and extrusion mixing (melt blending), were used to determine the effect of processing conditions on the tensile and fatigue behavior of the blends after compression molding. It was found that both tensile (modulus, ultimate strength) and fatigue performances were improved with increasing vHDPE content. Based on the obtained data, a correlation between the blends composition and mechanical properties is reported. Moreover, it was observed that increasing the vHDPE content led to slower crack propagation rate, probably due to less defects (contamination) in the blends. Finally, a negligible difference in mechanical properties (fatigue resistance) between both mixing approaches was observed, but samples produced via powder mixing showed less viscous dissipation (heat generation) as the vHDPE content increased, leading to lower surface temperature rise which can be an advantage for specific applications.

Mechanical Properties of Concrete with Recycled High-Density Polyethylene Macro Flat Fiber and Rice Hull Ash as Partial Replacement to Cement

As concrete is still one of the most used in construction,developmenton improving its strength andpossible reduced environment impactis necessary.This study determines the mechanical properties of concrete with the addition of recycled High-Density Polyethylene (HDPE) Macro Flat Fiber (MFF) and Rice Hull Ash(RHA) as partial replacement to cement. The objective of this study is to identify theoptimum mix ratio for compressive and flexural strength of concrete. Various percentage of HDPE MFF (0.5%, 0.75%, and1.0%)and 10% partial replacement of RHA to cementis incorporated in the mixture. The RHA is obtained through uncontrolled burning whileHDPE MFF is collected through shredding and manual cutting. The results showed thatthe addition of HDPE MFF had a positiveeffect on the compressive and flexural strength of concrete. The optimum value is achieved on concrete with 0.5% HDPE MFF and no RHA, as it had showed an average of 31.87 MPa with a 18.04% increase in compressive strength, and an average of 4.532 MPawitha 17.78% increase for flexural strength. Moreover, the combination with RHA had not showed promising results. It had been concluded that the addition of recycled HDPE MFF with no RHA increases the compressive and flexural strength of concrete.

The Effect of the Addition of Copper Particles in High-Density Recycled Polyethylene Matrices by Extrusion.

In this study, the effect of the recycling process and copper particle incorporation on virgin and recycled pellet HDPE were investigated by thermo-chemical analysis, mechanical characterization, and antibacterial analysis. Copper particles were added to pellet HDPE, virgin and recycled, using a tabletop single screw extruder. Some copper particles, called copper nano-particles (Cu-NPs), had a spherical morphology and an average particle size near 20 nm. The others had a cubic morphology and an average particle size close to 300 nm, labeled copper nano-cubes (Cu-NCs). The thermo-chemical analysis revealed that the degree of crystallization was not influenced by the recycling process: 55.38 % for virgin HDPE and 56.01% for recycled HDPE. The degree of crystallization decreased with the addition of the copper particles. Possibly due to a modification in the structure, packaging organization, and crystalline ordering, the recycled HDPE reached a degree of crystallization close to 44.78% with 0.5 wt.% copper nano-particles and close to 36.57% for the recycled HDPE modified with 0.7 wt.% Cu-NCs. Tensile tests revealed a slight reduction in the tensile strength related to the recycling process, being close to 26 MPa for the virgin HDPE and 15.99 MPa for the recycled HDPE, which was improved by adding copper particles, which were near 25.39 MPa for 0.7 wt.% copper nano-cubes. Antibacterial analysis showed a reduction in the viability of E. coli in virgin HDPE samples, which was close to 8% for HDPE containing copper nano-particles and lower than 2% for HDPE having copper nano-cubes. In contrast, the recycled HDPE revealed viability close to 95% for HDPE with copper nano-particles and nearly 50% for HDPE with copper nano-cubes. The viability of S. aureus for HDPE was lower than containing copper nano-particles and copper nano-cubes, which increased dramatically close to 80% for recycled HDPE with copper nano-particles 80% and 75% with copper nano-cubes.

Synthesis and characterization of recycled HDPE polymer composite reinforced with nano-alumina particles

Recycling of High-density Polyethylene (HDPE) plastic is a viable and economical method to progress in the path of a sustainable and eco-friendly initiative towards the eco-sustainable environment. This work is a pilot study to synthesize a polymer nanocomposite material from recycled HDPE reinforced with aluminium oxide nanoparticles to assess its potential applications as a packaging material. The microstructure of the newly synthesized material is characterized using scanning electron microscopy (SEM) analysis, and energy dispersive X-ray spectroscopy (EDS) analysis. X-ray diffraction (XRD) analysis was done to determine the crystallographic structure, while the thermal behaviour was analyzed through Thermogravimetric analysis (TGA) and differential Scanning Calorimetry (DSC) test. Recycled HDPE is already being used in a variety of applications, however, reinforcing with nano alumina particles will alter the properties of HDPE composite which opens up a new arena of possibilities in the field of electronic packaging.

Mechanical and morphological characterization of recycled HD-PE bio-composites based on alfa fibers and natural pozzolan

Abstract In this research work, waste plastic bottle caps made of high-density polyethylene (HD-PE) were reincorporated as a matrix and reinforced by alfa short fibers and natural pozzolan particles. Using different weight percentages of both fillers of 5 wt% up to 30 wt%, three types of bio-composite materials have been produced; alfa short fibers/HDPE, pozzolan particles/HDPE, and alfa fibers pozzolan/HDPE. Specimens for each type of the biocomposites were prepared through the compression molding method. The objective of this study is to investigate the effect of different content of alfa short fibers and pozzolan particles on the mechanical and morphological properties of the recycled HDPE matrix. Tensile test results revealed an enhancement in the mechanical properties for the three types of the biocomposites, an increase in tensile strength reached the maximum of 3573 MPa plus an interesting improvement in Young’s modulus with a maximum value of 3696 MPa. The toughness of the neat recycled HD-PE decreased by 212% by adding the natural filler whereas the modulus of resilience exhibited an increase of 138% compared to the neat recycled HD-PE. Therefore, the good rheological behavior of these bio-composites makes it possible to produce competitive materials and allows the reduction of plastic waste in the environment.

Eco-Friendly Asphalt Containing Recycled High-Density Polyethylene (HDPE): Performance Assessment and Cost Analysis

Utilization of the recycled waste materials for new products is considered as a viable solution for saving the environment. This study paper targets the performance evaluation of hot-mix asphalt made with the modified bitumen 60/70 containing 3 % and 5 % of recycled high-density polyethylene (HDPE) (by the weight of optimum bitumen). First, the properties of modified bitumen mixtures including specific density, penetration depth, ductility, and softening point were measured. Then, the properties of asphalt mixtures made with the modified bitumen including rutting depth and resilient modulus were measured. Findings indicated the suitability of recycled HDPE available in Iranian market in the development of eco-friendly asphalt mixtures. Results showed a 49 % decrease in penetration depth and a 15 % increase in softening point for the suggested modified bitumen mixture containing3 % of recycled HDPE compared to those of control bitumen mixture, i.e. the bitumen mixture containing 0 % of recycled HDPE. Results also showed a 47 % decrease in rutting depth and a 113 % increase in resilient modulus of asphalt made with the bitumen mixture containing 3% of recycled HDPE compared to those of control asphalt mixture, i.e. the asphalt mixture containing 0 % of recycled HDPE. The results showed that the suggested asphalt mixture can be an appropriate option to be adopted not only in moderate climates but also in tropical climates as its characteristics become comparable to those of the bitumen 40/50 and the bitumen 30/40. Replacing a portion of bitumen by the recycled HDPE not only improves the characteristics of asphalt, but also has a positive impact on reducing the natural resource depletion and environmental pollution resulting from burning and/or the retention of plastic waste left in nature. The suggested eco-friendly asphalt is also cost effective.

Railway Bearing Prototypes Based on Plastic Waste HDPE and Nylon-Resin Fiber Epoxy

Introduction: Material composite is ingredient congested when two or more materials, each with characteristics, are combined to make material new which nature more superior than component the main thing is in certain applications. Method: In this study, composite bearing specimens were made using the method compression molding with two variation composition that is HDPE 60% + fiber nylon 5% + epoxy 35% and composition HDPE 60% + 10% nylon fiber + 30% epoxy. This manufacturing method is done by inserting recycled HDPE, fiber, nylon, and epoxy resin into the mold. Next, the pressing process is carried out with a hydraulic press and heated at a temperature of 220°C using oven electricity. Results: Results testing material shows strong bending highest on variation composition HDPE 60% + fiber nylon 10% + Epoxy 30% that is as big as 17.21 MPa. Strength bending in this composition has increased from previous studies with a bending strength of 15.66 Mpa, but not yet. Fulfill standard bearing rail composite JIS E 1203:2007 as big as 17.5 MPa. Results testing pull with standard ASTM D638 obtained the highest tensile strength at 60% HDPE + 10% nylon fiber + 30% epoxy of 8.64 Mpa. Tensile strength on composition this experience enhancement from a previous study of 0.5041 MPa. Conclusion: Prototype bearing rail train fire composite made to a 1:4 scale of the original size, which refers to standard JIS E 1203:2007. Prototype bearing rail train fire conducted material testing using bending and tensile tests.

Thermal-mechanical properties of stabilized clayey sand subgrade soils

Stabilization of the problematic subgrade soils is extensively studied over the years to enhance their engineering properties, most commonly strength and deformation characteristics. Recent studies demonstrated that the recycled waste materials are viable sustainable alternatives to chemical stabilizers resulting in low costs and environmentally friendly solutions. In this research, investigative studies were performed to evaluate the durability, mechanical, and thermal properties of clayey sands when treated with recycled high-density polyethylene (HDPE) plastic pellets and flakes with cement as a binder. A series of experimental laboratories studies were performed to evaluate the unconfined compressive strength, strength retention, swell pressure, soil loss, and volumetric strain of the stabilized soils with different wetting-drying durability cycles. In addition, this study addressed the influence of recycled plastic form and dosage content on the thermal conductivity of the candidate soil. Threshold dosage contents of recycled plastics are established based on the multiscale scale criteria that suffices all the thermal, mechanical, and durability requirements of treated soils. This research indicated that the addition of recycled HDPE plastics led to enhancement in strength, swell characteristics, durability, and thermal conductivity when compared to the untreated soils and demonstrated the feasibility of using recycled plastic wastes in sustainable stabilization practices.

Valorization of Potential Post-Consumer Polyethylene (PE) Plastics Waste and Ethiopian Indigenous Highland Bamboo (EHB) for Wood Plastic Composite (WPC): Experimental Evaluation and Characterization

The best approaches to minimizing resource scarcity, removing valuable waste streams, and re-establishing a circular economic chain of recycled thermoplastics are to cascade them into product life cycles and their valorization combined with sustainable raw materials. As one part of this goal, WPC was formulated from three recycled PE plastic wastes: linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), and underutilized EHB. The chemical composition of EHD, chemical structure, crystallinity, melting and crystallization points, residual metal additives, and polycyclic aromatic hydrocarbons (PAHs) of recycled PE were investigated using standard chromatographic and spectroscopic methods such as HPAEC-UV/VIS, FTIR, DSC, GC/MSD, and XPS. The properties of WPC formulations from different compositions of bamboo particles (BP) as dispersed phase, individual recycled PE plastics, and equal melt blend (EM) as polymer matrix were investigated extensively and measured with a known standard. These comprised tensile strength (TS), modulus of elasticity (TM), flexural strength (FS), modulus of rupture (FM), and unnotched impact strength (UIS). It also included the effect of various alkaline surface treatment ranges on the interface surface interaction. The results show improved mechanical properties for all blending ratios of surface-treated BP, which resulted from better encapsulation in the polymer matrix. Despite its inherent immiscibility, WPC formulation from equal melt blending revealed unusual properties compared to separate phase blends, which is attributed to thermally induced cross-linking. This implies that melt blending of the weakest and cheapest recycled LLDPE with relatively cheap recycled MDPE and HDPE improves the properties of the blend, particularly toughness, while simultaneously retaining some of their properties.

Life cycle sustainability assessment of non-beverage bottles made of recycled High Density Polyethylene

The current plastic industry is associated with climate change, fossil fuel depletion and littering of plastic waste. To reduce these environmental impacts, companies and governmental bodies are increasingly adopting strategies based on the concept Circular Economy. However, circular decision-making is usually based on analyses that do not provide enough insights in every sustainability dimension, risking burden-shifting. In this study, environmental, economic and social life cycle assessment (LCA) techniques have been integrated into an overarching sustainability life cycle assessment (LCSA) to assess the impact of recycling High Density Polyethylene (HDPE) non-beverage bottles. The study assesses the impact in 11 environmental categories, the life cycle costs, and the social risks associated with the related economic sectors. An ad-hoc system expansion approach was developed to overcome the multifunctionality issue so commonly challenging in circular systems. The results indicate that using recycled HDPE leads to significant reductions in all the considered environmental categories. The economic analysis indicated that the material cost of recycled HDPE is slightly lower than for virgin HDPE, but the manufacturing costs are higher and highly dependent on the specific value chain. The social risks of recycling were found to be higher than for virgin plastic production, and mainly occurring outside the country where the recycling takes place (The Netherlands). Nevertheless, this analysis presents high uncertainty due to the heterogeneity in the recycling sector of the database. This study shows how the LCSA approach can be used to assess and compare the impacts and benefits of circular strategies and calls for further efforts to develop higher disaggregated social risk databases.

Development of an advanced extrusion process for the reduction of volatile and semi-volatile organic compounds of recycled HDPE from fuel tanks

Plastic fuel tanks of vehicles are typically made by high density polyethylene (HDPE). The easiness of the dismantling procedure from end-of-life vehicles and the intrinsic recyclability of HDPE allows them to be accounted in principle in the “white list” of recyclable components. However, the strong contamination and odor produced by the volatile (VOCs) and semi-volatile (SVOCs) organic compounds which have been absorbed during the service life, drastically hinders the use of this end-of-life material. This aspect reduces its actual recyclability, especially in higher-value applications. In this paper, we report a study on an innovative extrusion process specifically designed for the stripping out of these organic contaminants. We also report an in-depth analytic approach to identify their nature and fraction, as a way for ranking the effect of the different processing conditions, which have been tested. The developed extrusion process uses a co-rotating twin-screw extruder with degassing points and the injection of water as medium for desorbing the organic contaminants. The analytic approach is based on headspace (HS) sampling associated to gas chromatography coupled to a mass spectrometric detection (GC–MS). The multivariate approach of the Principal Components Analysis (PCA) was applied on the entire dataset collected in the experiments, comprising the HS GC–MS data, the different process parameters, and the mechanical and thermal data. As a result, the effect of the processing conditions and all the organic contaminants present in the material were identified.The developed extrusion process allows one to obtain a material with higher opportunity to be used in applications which require enhanced performance, therefore, to be considered effectively recyclable, further reducing the environmental impact of the end-of-life vehicles.

Characterization of the Thermal, Structural, and Mechanical Properties of Recycled HDPE

AbstractHigh‐density polyethylene (HDPE) is one of the most popular plastics used in industry. Although it replaces many natural resources, due to the low cost and easy processing, its ever‐increasing wastes make it harmful for the environment. Thus, many processes are used in order to recycle it. In the present study, the properties of recycled HDPE (r‐HDPE) compared to virgin HDPE are investigated. The structural studies are performed by X‐ray diffraction (XRD). The thermal properties of virgin HDPE and r‐HDPE are measured by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Moreover, the mechanical properties are examined by Instron tensile strength experiments. Comparing the results, r‐HDPE does not show any significant differences regarding its structural and thermal properties. Additionally, it is found that r‐HDPE has a slight increase in tensile strength. As a result, considering that the mechanical process to produce r‐HDPE does not affect its general properties, it is suitable for further processing.

Effects of Poly(vinylchloride)-Maleic Anhydride as Coupling Agent on Mechanical, Water Absorption, and Morphological Properties of Eggshell Powder Filled Recycled High Density Polyethylene/Ethylene Vinyl Acetate Composites

The recycled high density polyethylene (rHDPE)/ethylene vinyl acetate (EVA)/ eggshell composites using poly(vinylchloride)-maleic anhydride (PVC-MA) as coupling agent was compounded using Brabender internal mixer. The results showed that the compatibilization of rHDPE/EVA blends was enhanced by the addition of 6 phr of PVC-MA. Furthermore, the tensile, water absorption resistance, and interfacial adhesion properties were studied. Tensile properties such as tensile strength and Young’s modulus were improved, while the elongation at break was reduced by the addition of PVC-MA. The water absorption resistance was improved upon PVC-MA addition to the composites.

Graphene: A multifunctional additive for sustainability

The purpose of this work is to demonstrate how the addition of graphene to a polyethylene resin formulation can allow for a large amount of recycled resin to be used without sacrificing the physical properties of the formulation. We investigated the effects of graphene addition on the rheology, thermal and mechanical properties of a prime high-density polyethylene (prime HDPE) with post-industrial recycled HDPE (recHDPE) blends. The viscosity and mechanical results, along with scanning electron microscopy analysis suggests that graphene acts as a reinforcing filler, thermal stabilizer, and potential compatibilizer for the blends of prime/recHDPE. The experimental findings showed that the addition of graphene resulted in a significant morphology refinement that facilitated replacing up to 50% of a prime HDPE with recHDPE, without compromising the mechanical performance.

Mechanical and Morphological Properties of Fluted Pumpkin Stem Fiber (Telfaira occidentalis) Recycled High Density Polyethylene Nanocomposites

The outstanding characteristic properties of nanographene such as high aspect ratios and improved mechanical properties in comparison with other types of nanofillers like carbon nanotubes and clays has accelerated their use as nanosize filler in polymer matrix composites. The litter of agro-wastes is a critical issue which must be addressed for the preservation of the global environment. The effect of nanographene addition on the mechanical and morphological properties of nanocomposites prepared using fluted pumpkin stem fiber (FPF) and recycled high density polyethylene (R-HDPE) was investigated. Four weight levels of nanographene 0, 0.5, 1.5 and 2.5 wt % were mixed with 65 wt. % HDPE, 35wt. % FPF and 3wt% maleic acid anhydride produced using melt compounding and the extruded nanocomposites was shaped by injection molding machine for the mechanical tests. The results showed that addition of 0.5 wt % nanographene increased the flexural strength, flexural modulus and notched impact strength by 24.77MPa, 1800MPa and 32.61J/m2, compared to the control samples 20.5MPa, 1500MPa and 19.35J/m2 respectively. Although the addition of nanographene to the FPF/HDPE composite significantly improved the flexural strength, flexural modulus and notched impact strength, these improvements came at a unique nanographene loading of 0.5 wt %. The morphological images revealed that the samples with nanographene loading of 0.5 wt. % showed no fiber pullout/holes, whereas higher contents (1.5-2.5wt %) of nanographene exhibited fiber pullout/holes and were easily agglomerated. This study has shown that fluted pumpkin stem fiber could be used in composite formulation with good results comparable to wood-plastic-composites.

Physical and Mechanical Properties of Agro-Waste Filled Recycled High Density Polyethylene Biocomposites

Natural plant fiber/agricultural waste materials have potential in composites due to their eco-friendliness, low cost and sustainability. Plastic and agro-wastes dumping are threatening concerns that must be settled for the protection of the worldwide ecosystem. In this study, the physical and mechanical properties of rice husk flour (RHF), corncob flour (CCF), walnut shell flour (WSF) and wood flour (WF) agro-waste filled recycled high density polyethylene biocomposites were investigated. Results showed bulk densities of RHF 350 kg/m3, CCF 310 kg/m3, WSF 400 kg/m3 and WF 250 kg/m3. Results showed moisture content of RHF 7%, WSF 6.4%, CCF 6% and WF 8%. Particle size distribution of 60-100 mesh size of the fillers was 0.295 mm to˂0.125 mm. Results showed that WF composite showed higher flexural modulus of 3.0 GPa and impact strength of 60 J/m followed by RHF with flexural modulus of 2.75 GPa and WSF with impact strength of 54.4 J/m compared to the control sample of 1.75 GPa and 38 J/m. The flexural strength of WF composite was 27.4 MPa followed by RHF composite 25.4 GPa, CCF composite 20.1 GPa and WSF composite 18.1 GPa compared to the control sample of 30.5 GPa. The higher bulk densities of RHF, WSF and CCF resulted in fiber accumulation at some parts of the composite, thereby causing weak points and the resultant lower mechanical properties compared to WF composites with lower bulk density. The study has shown that agro-waste fillers could be used in composite production with good results compared to WF composites.

Processability and Physical Properties of Compatibilized Recycled HDPE/Rice Husk Biocomposites

The circular economy promotes plastic recycling, waste minimization, and sustainable materials. Hence, the use of agricultural waste and recycled plastics is an eco-friendly and economic outlook for developing eco-designed products. Moreover, new alternatives to reinforce recycled polyolefins and add value to agroindustrial byproducts are emerging to develop processable materials with reliable performance for industrial applications. In this study, post-consumer recycled high-density polyethylene (rHDPE) and ground rice husk (RH) of 20% w/w were blended in a torque rheometer with or without the following coupling agents: (i) maleic anhydride grafted polymer (MAEO) 5% w/w, (ii) neoalkoxy titanate (NAT) 1.5% w/w, and (iii) ethylene–glycidyl methacrylate copolymer (EGMA) 5% w/w. In terms of processability, the addition of RH decreased the specific energy consumption in the torque experiments with or without additives compared to neat rHDPE. Furthermore, the time to reach thermal stability in the extrusion process was improved with EGMA and MAEO compatibilizers. Tensile and impact test results showed that using coupling agents enhanced the properties of the RH composites. On the other hand, thermal properties analyzed through differential scanning calorimetry and thermogravimetric analysis showed no significant variation for all composites. The morphology of the tensile fracture surfaces was observed via scanning electron microscopy. The results show that these recycled composites are feasible for manufacturing products when an appropriate compatibilizer is used.