High-density Polyethylene Particles Research Articles

A comprehensive approach to physical recycling of hazardous waste HDPE industrial drums: Overcoming challenges in safety and foam interference

The regeneration of hazardous waste plastics are prerequisites for the sustainable development, and treatment of waste high density polyethylene (HDPE) industrial drums poses a significant challenge in the field of waste plastic recycling. In this study, a multi-step collaborative system was established for the decontamination and classification process of hazardous waste industrial drums. The yield of recycled HDPE particles exceeds 80 wt%. Through multiple experimental verifications, the optimal addition amount of antifoaming agent is 0.6 wt%, achieving the best balance between antifoaming effect and consumption. The motion process of antifoaming agent microdroplets in a static mixer was simulated. And also, through large-scale statistical analysis, the stability and reliability of physical properties and environmental safety of recycled HDPE particles were verified, supporting their reuse in various fields. In sum, this study proposes a feasible physical recycling strategy for hazardous waste HDPE industrial drums, and provides basic data from industrial practice and technical insights.

Characterization of HDPE microparticles in sludge aerobic digestion and their influence on the process

The occurrence of microplastics (MPs) in wastewater has been studied in the last years. The high efficiency of their removal from wastewater is linked to their transfer to the sludge. In this work, the effect of high-density polyethylene (HDPE) on aerobic digestion was evaluated and these MPs were monitored, characterizing them by three different techniques. Two parallel batch digesters were monitored. AD-Control (meaning Aerobic Digester) operated as a reference, with no external HDPE particles, whereas these polymeric fragments were introduced to the second aerobic digester (AD-HDPE) using ring pulls as microplastic support. FTIR, Raman spectroscopies and fluorescence analysis of these microparticles showed some relevant results that should be highlighted. Higher fluorescence appeared after 7 days in the digester. It coincided with an increase of active volatile suspended solids (AVSS) in the AD-HDPE, which means that an increase of the microbial activity took place. Despite the presence of HDPE particles in the sludge, the digester performance was not compromised. Besides, the HDPE particles did not affect the microbial diversity (Shannon index) of the bacterial community at the end of the experiment compared to the bacterial community of the aerobic digester control tank. Based on the analysis of the relative abundances of microbial taxa, it was concluded that HDPE had selective effects on sludge microbial community, increasing the relative abundance of Bacteroridota phylum.

Cold spray deposition of high density polyethylene composite powders

In this paper, we investigate the use of the cold spray additive manufacturing technique to deposit micron-sized composite particles of high-density polyethylene (HDPE) compounded with either micron or nanometer sized particles of silicon dioxide (SiO2) or copper (Cu). In this study, the mass fraction of the SiO2 and copper particles added into the final composite powders was varied between 0.5 % and 9.1 % and the deposition efficiency of each composite powder was measured. Deposition of the composite powders onto an HDPE substrate was successful even at the highest particle loadings tested. In each case, an optimal mass fraction of silicon dioxide or copper particles was observed with a maximum value of deposition efficiency larger than that of the pure HDPE. For the silicon dioxide composite powders, the deposition efficiency nearly doubled compared to the pure HDPE powders. The improvement of deposition efficiency at moderate particle loadings is likely due to the increase in the impact kinetic energy of the particles resulting from the increase in the density of the composite powders. While the decrease in deposition efficiency at high particle loadings is likely the result of the increased coverage of the silicon dioxide and copper particles on the surface of the HDPE powders limiting the interaction between the HDPE of the composite powder with the HDPE substrate. SEM images show that it is possible to create a smooth, dense, and uniform thin-film polymer composite coating using cold spray.

The study of High-Density Polyethylene (HDPE) waste utilization into particle board

This research discusses related to one of the processing of waste, especially HDPE waste. HDPE waste is another alternative besides wood to make particle board. HDPE particle board takes advantage of these properties to provide a strong and durable alternative. The use of HDPE particle board provides significant benefits in the context of sustainability and the environment. In the manufacture of particle board in this study there were differences in temperature variations, so the variable in this study was temperature. Sample A has a temperature of 130° and sample B has a temperature of 160°. The particle board is pressed for 20 minutes using a hot press machine using 1 x 1 m molding. Testing of this HDPE particle board includes testing of physical properties, namely in the form of Density and chemical testing in the form of Acidity resistance and Alkalinity resistance. The standards in this study refer to SNI 03-2105-2006 regarding Particle Boards, SNI 01-7201-2006 regarding Plywood and block boards with beautiful paper faces, and ASTM D543. The density test showed a value of 0.90 gr/cm3 in the average sample A and 0.75 gr/cm3 in the average sample A. The results of the ANOVA analysis on the Density test showed that there was a significant difference between each sample and each treatment. the results of the t-Test showed that the treatment of sample A did not meet the standard, while the treatment of sample B met the SNI 03-2105-2006 standard. The acidity and alkalinity resistance were tested visually with the results that the temperature at 130° was more susceptible to reaction than the temperature at 160° Objectives: To find out the result of Density test, Acidity, and Alkalinity resistance of HDPE Particle Board is it already fulfill the standard ; To determine the temperature that has the most significant impact on the performance of HDPE Particle Board. Method and results: 1) Process of making the Particle Board, the process are include material preparation, material weighing, shredding, cleaning, drying, and pressing. 2) Sample Testing, the treatment that used is about variation of temperature. Variable that be used in this study consist of Density, Acidity, & Alkalinity. 3) Data Analysis, by using ANOVA Single Factor and t-Test. Conclusion: The results of Density test by t-Test analysis showed that the treatment of sample A did not meet the standard, while the treatment of sample B already fulfill the SNI 03-2105-2006. In Acidity and Alkalinity resistance there are indicators according to SNI 01-7201-2006 in the form of softening and open cracks in several samples. Density test results show the variable B (160°) is at 0.75 gr/cm3 and already fulfil the standard. Visual test results of Acidity and Alkalinity resistance show the variable B (160°) is more resistant to the effects of acids and bases. So that the optimal variable is at a temperature of 160°.

Determination of microplastics in the wetlands of specific regional area and unveiling the toxic properties of predominant HDPE particle on animal and plant models

Microplastics are emerging environmental pollutants that cause a great threat to all forms of living organisms. However, the information on MPs existence in freshwater sources and its environmental implications on freshwater associated flora and fauna remain limited. Hence, the present study was designed to identify the presence of MPs in the sediments of major wetlands of Coimbatore, Tamilnadu, India and to assess the toxicity of predominantly detected MPs in animal and plant models. In this study, six different types of MPs such as filaments (FI), fragments (F), irregular filaments (IF), pellets (P), films (FM) and colored fragments (CF) were identified from the samples through Phase contrast and Scanning Electron Microscopy. Besides, high Density Polyethylene (HDPE) was identified as predominant MPs from the wetlands by micro–Raman spectroscopy analysis and hence, HDPE has been selected for further toxicity assessment studies. In toxicity study, HDPE exposure significantly affected the phenotype, survival and hatching rate, heart shape and function of the zebrafish embryos. Moreover, HDPE toxicity significantly increased the expression pattern of major stress marker genes such as P5CS, CAT, SOD and APX1 in Sorghum bicolor plant. This study spotlighted the presence of MPs in major wetlands of Coimbatore and elucidated the toxicity nature of predominant MPs pollutant HDPE in zebrafish embryos and major agriculture crop S. bicolor as the first report.

Selected properties of MDF boards bonded with various fractions of recycled HDPE particles

Selected properties of MDF boards bonded with various fractions of recycled HDPE particles.The substitution of non-renewable, formaldehyde-based amine wood binders in the wood-based composites industry is one of the main directions of trials and research. On the other hand, a bigger effort should be put into carbon capture and storage (CCS) activity, especially in the case of oil-based plastics, to extend their life in the products. The aim of the research was to use waste high-density polyethylene (HDPE) in MDF panels and determine their selected properties, including modulus of elasticity in bending, bending strength, internal bond, thickness swelling, water absorption, screw withdrawal resistance, density profile when referred to the fraction of used HDPE.The panels were created in laboratory conditions with a 50% weight content of HDPE particles of different fractions (<1 mm, <2 mm, <4 mm, and a mixed fraction containing 25% of each fraction and unsorted waste). The results show that the highest strength and modulus of elasticity were obtained for panels with plastic fractions below 1 mm. This fraction also achieved the lowest results for water absorption and thickness swelling. The fraction of the used plastic has no significant effect on screw withdrawal resistance. The negative impact of using larger fractions in the board is noticeable, however, for the mixed fraction, the results are similar to the finest fraction in terms of the internal bond, thickness swelling, and water absorption. The addition of HDPE can have a beneficial effect on the parameters of MDF panels. It is possible to create fibreboards from wasted plastic, store carbon dioxide in them, and upcycle them. In the discussed panels, the only binder for wood fibres was HDPE, so panels should not emit formaldehyde from the binder.

A Mixture Design of Microconcrete Containing Quartz and Discarded HDPE Particles: Case Study

This work investigated the feasibility of replacing quartz aggregates with discarded high-density polyethylene (HDPE) particles in a cementitious matrix for secondary structural applications in civil construction. A mixture design technique was used to assess the effect of the constituents on the physical-mechanical properties of composites, such as density, water absorption, flexural strength, compressive strength, and dynamic modulus. The aggregate/cement ratio ranged from 3.76 to 5.25, and the water/cement ratio was kept constant at 0.5, whereas a minimum of 30 vol% HDPE particles was considered in the system. The optimized responses and fractions were determined by considering five different scenarios through the statistical method desirability. The gradual replacement of quartz aggregates by HDPE led to a more porous material, increasing water absorption and reducing mechanical properties. However, these composites exhibited a less rigid characteristic, revealing a less brittle failure mode. Whereas the optimized density was obtained for the minimum matrix and maximum HDPE fractions, the optimal response for the mechanical properties and water absorption presented an opposite behavior, that is, maximum cement matrix fraction and minimum HDPE fraction. Multiobjective optimization proved to be a promising technique for identifying the optimal mix of recycled microconcrete for a given application.

Sorption of representative organic contaminants on microplastics: Effects of chemical physicochemical properties, particle size, and biofilm presence

Microplastic pollution has attracted mounting concerns worldwide. Microplastics may concentrate organic and metallic contaminants; thus, affecting their transport, fate and organismal exposure. To better understand organic contaminant-microplastic interactions, our study explored the sorption of selected polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), α-hexabromocyclododecane (α-HBCDD), and organophosphate flame retardants (OPFRs) on high-density polyethylene (HDPE) and polyvinylchloride (PVC) microplastics under saline conditions. Sorption isotherms determined varied between chemicals and between HDPE and PVC microplastics. Log Freundlich sorption coefficients (Log KF) for the targeted chemicals ranged from 2.01 to 5.27 L kg-1 for HDPE, but were significantly lower for PVC, i.e., ranging from Log KF data (2.84 – 8.58 L kg-1). Significant correlations between chemicals’ Log KF and Log Kow (octanol-water partition coefficient) indicate that chemical-dependent sorption was largely influenced by their hydrophobicity. Sorption was evaluated using three size classes (< 53, 53 – 300, and 300 – 1000 µm) of lab-fragmented microplastics. Particle size did not significantly affect sorption isotherms, but influenced the time to reach equilibrium and the predicted maximum sorption, likely related to microplastic surface areas. The presence of biofilms on HDPE particles significantly enhanced contaminant sorption capacity, indicating more complex sorption dynamics in the chemical-biofilm-microplastic system. Our findings offer new insights into the chemical-microplastic interactions in marine environment.

Comprehensive Study on the Performance of Waste HDPE and LDPE Modified Asphalt Binders for Construction of Asphalt Pavements Application.

This research is aimed at investigating the mechanical behavior of the bitumen by the addition of high-density polyethylene (HDPE) and low-density polyethylene (LDPE) obtained from waste plastic bottles and bags. Polymers (HDPE and LDPE) with percentages of 0%, 2%, 4%, and 6% in shredded form by weight of bitumen were used to evaluate the spectroscopic, structural, morphological, and rheological properties of polymer-modified binders. The rheological properties for different factors; viscosity (ἠ) from Rotational Viscometer (RV), rutting factor G*/Sin (δ), fatigue characteristics G*. Sin (δ), for the modified binder from dynamic shear rheometer (DSR), Short and long-term aging from rolling thin film oven (RTFO), and pressure aging vessel (PAV) was determined. The thermal characteristics, grain size, and texture of polymers for both LDPE and HDPE were found using bending beam rheometer (BBR) and X-ray diffraction (XRD), respectively. Fourier transform infrared (FTIR) analysis revealed the presence of polymer contents in the modified binder. Scanning electron microscopy (SEM) images revealed the presence of HDPE and LDPE particles on the surface of the binder. Creep Rate (m) and Stiffness (S) analysis in relationship with temperature showed a deduction in stress rate relaxation. Results have revealed the best rutting resistance for 6% HDPE. It also showed an improvement of 95.27% in G*/Sin (δ) which increased the performance of the bituminous mix. Similarly, the addition of 4% LDPE resulted in maximum dynamic viscosity irrespective of the temperatures. Moreover, fatigue resistance has shown a significant change with the HDPE and LDPE. The festinating features of waste plastic modified binder make it important to be used in the new construction of roads to address the high viscosity and mixing problems produced by plastic waste and to improve the performance of flexible pavements all over the world.

Impact of the surrounding environment on antibiotic resistance genes carried by microplastics in mangroves

The pollution of antibiotic resistance genes (ARGs) carried by microplastics (MPs) is a growing concern. Mangroves are located at the intersection of land and sea and are seriously affected by MP pollution. However, few studies have systematic research evaluating the transmission risk of ARGs carried by MPs in mangroves. We conducted in situ experiments by burying five different MPs (polypropylene, high-density polyethylene, polystyrene, polyethylene glycol terephthalate, and polycaprolactone particles) in mangroves with different surrounding environments. A total of 10 genes in the MPs of mangroves were detected using quantitative real-time polymerase chain reactions, including eight ARGs and two mobile genetic elements (MGEs). The abundance of ARGs in Guanhai park mangroves in living areas (GH) was higher than that of Gaoqiao mangroves in protected areas (GQ) and Beiyue dike mangroves in aquaculture pond areas (BY). Pathogenic bacteria, such as Acinetobacter, Bacillus, and Vibrio were found on the MP surfaces of the mangroves. The number of ARGs carried by multiple drug-resistant bacteria in the GH mangroves was greater than that in the GQ and BY mangroves. Moreover, the ARGs carried by MPs in GH mangroves had the highest potential transmission risk by horizontal gene transfer. Sociometric and environmental factors were the main drivers shaping the distribution characteristics of ARGs and MGEs. Polypropylene and high-density polyethylene particles are preferred substrates for obtaining diffuse ARGs. This study investigated the drivers of ARGs in the MPs of mangroves and provided essential guidance on the use and handling of plastics.

Size-dependent transfer of microplastics across the intestinal wall of the echinoid Paracentrotus lividus.

The fate and toxicity of ingested marine microplastics (MPs) have been of major concern in aquatic ecotoxicology for the last decade. Although their ingestion by a wide range of marine organisms has been proven, the uptake of MPs within organs is not yet fully understood and relies on the ability of ingested microplastics to transfer from the gut to tissues beyond the digestive wall (i.e., translocation). The present study investigates the in vitro transfer of fluorescent high-density polyethylene particles of different sizes classes (1-5µm; 10-29µm; 38-45µm) across the intestinal wall of the sea urchin Paracentrotus lividus using Ussing chambers. Small microplastics (1-5µm) were proven to be able to cross the intestinal wall of P. lividus and reach the coelomic fluid, while larger microplastics (≥ 10µm) were not observed to cross the intestinal wall. Results demonstrate a size-dependent passage of polyethylene microparticles across the intestinal walls of P. lividus for the first time, highlighting the suitability of Ussing chamber systems to study the transfer of MPs across the intestinal wall of animals.

Millimeter-Scale Percolated Polyethylene/Graphene Composites for 5G Electromagnetic Shielding

A concern regarding electromagnetic interference (EMI) shielding materials with high absorption capacity was raised as fifth-generation (5G) telecommunication developed. However, current shielding materials are generally focusing on reflection. To address this breakthrough in EMI shielding materials, a high-density polyethylene (HDPE)/few-layer graphene composite millimeter (mm)-scaled percolation structure was investigated for K-band electromagnetic shielding applications. The HDPE/multilayer graphene (MLG) composite with an mm-scale percolation structure exhibits excellent electrical and thermal conductive properties and shows an absorption-dominant electromagnetic shielding effect. In particular, the best optimized EMI shielding effectiveness of the composite at 26 GHz was 71.25 dB and showed an excellent absorption-dominant shielding mechanism with an absorption coefficient of 0.78. The mm-scaled percolation structure revealed that it effectively works in the K-band rather than the X-band by optimizing multiple reflection phases by the mm-scale HDPE particle.

Assessing the effects of polyethylene microplastic aging on the sorption of pyrene via simulated sunlight irradiation

The sorption and transport of environmental pollutants with microplastics (MPs) is a growing environmental concern due to the increased use and emissions of MPs and their high affinity toward many organic contaminants. This study examines the impacts of environmental aging of high-density polyethylene (HDPE) via sunlight irradiation on its molecular interactions with pyrene, a model hydrophobic organic pollutant. HDPE MPs were artificially aged under simulated sunlight irradiation for different exposure times. During aging treatments with simulated sunlight irradiation, morphological changes, such as cracks and rough surfaces, were induced on the HDPE particles; however, destructive oxidation was not observed. Batch sorption experiments were conducted on the aged and pristine MPs. Results reveal that pyrene sorption on MPs was enhanced for the aged HDPE particles and the sorption increases with increased irradiation time, indicating that aged HDPE has a higher sorption capacity than the pristine one. These results are attributed to the physical alteration in HDPE, which increases the surface area and promotes aqueous pyrene sorption on MPs. These results provide possible mechanistic explanations for the accumulation of hydrophobic organic pollutants with MPs in aquatic environments.

An experimental study on compressive properties of high density polyethylene-nano alumina-groundnut shell hybrid composites

In recent years, bio-fibers have become increasingly popular as reinforcements for thermoplastics and thermosets. Research into the use of natural fibers such flax, bamboo, sisal, hemp, and jute as reinforcing elements in the production of various composites has been considerable. Groundnut shell particles and refractory alumina powder were combined with high density polyethylene (HDPE) polymer matrix to create new bio-based composites in this study. The results were promising. Composite boards were synthesized by with HDPE with randomly distributed nano alumina and groundnut shell particles with volume percentages of 95:0:5, 95:2.5:2.5 and 95:5:0. ASTM standards were used to evaluate the compressive, shore hardness and water intake characteristics of the composites. The highest compressive load, compressive strength, increase in area, maximum displacement, displacement at break and compressive strain were analyzed for the specimen having HDPE, nano alumina and groundnut shell particles proportion 95:2.5:2.5. Using HDPE, nano alumina, and groundnut shell particles, Possibly a composite might be produced that could replace wood in many settings.

Simultaneous sorption behaviors of UV filters on the virgin and aged micro-high-density polyethylene under environmental conditions

The simultaneous sorption behaviors of four analytes from the UV filters group, benzophenone (BPh), 4-methylbenzylidene camphor (4MBC), benzophenone 3 (BPh3), and benzophenone 2 (BPh2) on virgin and aged high-density polyethylene (HDPE) with a particle size of 125 μm in milliQ and river water were examined in this study. The aging processes of HDPE particles were carried out with the use of simulated sunlight. Conducted research revealed that the sorption of UV filters on HDPE particles follows pseudo-second-order kinetics. A Temkin isothermal model best described the adsorption process for 4BMC, BPh, BPh3, BPh2 on aged HDPE in river water, and 4MBC, BPh, BPh3 on virgin HDPE in milliQ water. The adsorption of BPh2 onto virgin MPs in milliQ water was consistent with the Langmuir isothermal model. Environmental conditions and physicochemical properties of analytes influenced the sorption mechanism between UV filters and MPs particles. It was observed that the main mechanisms responsible for the sorption of BPh, 4MBC, BPh3, and BPh2 on the surface of HDPE are hydrophobic interactions, that may change through the involvement of electrostatic interactions.

Thermo‐oxidative degradation during sintering of polyethylene particles

AbstractPolymer sintering is not only a well‐established procedure for producing functional polymeric parts, but it is also the basis for the relatively new additive manufacturing technique, selective laser sintering. Although studying the impact of thermo‐oxidative degradation during sintering has significant practical importance, few studies have focused on this aspect of the sintering process. In the present work, we have investigated the active thermo‐oxidative degradation mechanisms during sintering of high‐density polyethylene (HDPE) particles, the conditions that promote them, and their respective impact on the morphological evolution of the polyethylene particles. To perform a comprehensive study, we have complemented the rheological, thermal, chemical, and morphological analysis of the sintered HDPE particles with the study of their ensemble pore structure. We observed two distinct degradation regimes. At the beginning, the relatively low concentration of oxygen in the particles led to the dominance of branching and resulted in a pore structure evolution limited to surface relaxation. In the second regime and with the diffusion of more oxygen, chain scission became the dominant route. In this regime, the emergence of highly mobile short chains markedly accelerated the pore evolution.

Synergistic toughening of iso‐polypropylene with high‐density polyethylene and polycyclooctene synthesized by ROMP

A series of different molecular weight Polycyclooctene(PCOE) rubber were synthesized via ROMP with G2 catalyst and Iso‐polypropylene (iPP), PCOE and high density polyethylene (HDPE) blends were prepared by micro twin‐screw extruder. The effects of PCOE molecular weight and content were investigated by studying the thermal, rheological and mechanical properties of the blends. We observed that the low molecular weight PCOE promoted the dispersion of HDPE, and as the molecular weight and content of PCOE rising, PCOE encapsulated HDPE particles entirely to form a connected core‐shell network structure in PP matrix and a certain degree of micro‐crosslinked structure which connected the PCOE ‘shell’. Micrographs of the fracture surfaces support the finding that PCOE promoted a finer dispersion and improved the morphological stability of the ternary blends as a compatibillizer. The increasing molecular weight of PCOE enhanced the molecular chains entanglement of the blends resulting in an increase on blends viscosity. The interfacial adhesion of PP/PCOE/HDPE ternary blends improved significantly as PCOE molecular weight increased from 12 kg/mol to 270 kg/mol. The impact strength of the PP/PCOE/HDPE blends increased by 3 times as compared with PP/HDPE blends owing to the addition of 15 wt% HDPE and 15 wt% PCOE(Mn = 270 kg/mol).

Wear properties of rapid tooling prepared by reinforcement of SiC/Al2O3 in HDPE domestic waste

This study highlights the fabrication of rapid tooling (RT) with improved wear properties from the domestic polymeric waste of high density polyethylene (HDPE) by reinforcement of SiC/Al2O3. The RT were prepared with HDPE and different particle sizes of SiC/Al2O3 (having single particle sizes (SPS); dual particle sizes (DPS) and tri-particle sizes (TPS) in form of reinforcement). The process started with establishing melt flow index (MFI) of the polymer composites (PC). After establishing MFI, the selected PC was used for filament wire preparation on twin screw extruder (TSE). The wires so prepared were put to mechanical testing, after which these wires were fed to 3D printer (fused deposition modelling (FDM) open source) for preparation of functional prototypes. The cylindrical pins printed on FDM were further subjected on pin on disc setup to investigate the wear properties. As per results of the present study it has been ascertained that the better wear properties of the feed stock filaments is achieved by reinforcement of ceramic particles and can be used as RT. The SEM analysis of the pins was performed to understand the wear mechanism. Finally, thermographs were plotted to ensure the thermal stability of RT and ensure the credibility of manufacturing process adopted.

Pore structure evolution during sintering of HDPE particles

Sintering is a processing technique in which loose particles consolidate at elevated temperatures to form porous monoliths. Sintering is also a critical stage in recent additive manufacturing method like selective laser sintering. In this study, using an affordable alternative to X-ray tomography technique, we analyze the pore structure evolution in sintered parts made of nascent high-density polyethylene (HDPE) particles in terms of pore surface genus and pore surface curvature. Also, we investigate the underlying microstructural development and macroscopic properties of sintered parts. It is observed that pore structure and macroscopic permeability are strongly influenced by the development of inter-particle contacts, while mechanical properties are also extensively influenced by microstructural evolution. For instance, the pore evolution is initially limited to surface relaxation and the merging of inter-particle bonds during which macroscopic permeability and relative density remain almost unchanged. However, the rapid mixing of the disentangled polymeric chains of nascent particles through these interfacial regions engenders a distinctive rise in compressive modulus. A study of the pore structure evolution using the approach adopted in this research might also provide the opportunity to understand how various sintering parameters can influence the evolution of inter-particle bonds, which coupled with the microstructural development, control the development of macroscopic properties in sintered porous polymeric parts.

Study on the light medium separation of waste plastics with hydrocyclones

The separation of waste plastics is an important part of solid waste recycling. Based on the density difference between high density polyethylene (HDPE) and polypropylene (PP), this paper used the experimental research and CFD numerical simulation to study the separation performance by using the light medium separation technology with hydrocyclones. Results showed that with the increase of feed flow rate, the pressure drop increased as a power function, the Newton efficiency peaked at the feed flow rate of 3.6 m3/h and peaked at the volume ratio of PP to HDPE particles of 2.0 respectively.