High-density Polyethylene Membrane Research Articles

Manufacture of biaxially oriented high-density polyethylene membranes with tunable properties via “structuring” processing strategy

Polyethylene (PE) is the most widely used thermoplastic resin in the world now. Among the endless number of PE products, films constitute over 50% of the consumer market and are applied in optical, packing and filtration areas according to distinct condensed structures. In this work, we prepared high-density polyethylene (HDPE)/liquid paraffin (LP) precursor films with various condensed structures by adjusting the LP content. Subsequently, we delved into the mechanism behind structural evolution during the uniaxial stretching process. Our findings reveal that an increase in LP content can increase the mobility of molecular chains, fostering the transformation of lamellae into an oriented microfiber structure during uniaxial stretching process. This improvement contributes to the enhanced stretchability of the films. Finally, we fabricated biaxially oriented membranes with distinct properties. These properties span from non-porous packaging films with exceptional optical characteristics to porous films suitable for specialized separation applications, achieved through the manipulation of the LP content. In summary, we manufacture different kinds of PE films through the strategy of “structure→ processing→ property”, which provides efficient access to design a given polymer material with desired structure and tunable properties via “structuring” processing.

Modelling of contaminant transport in heterogeneous vertical barrier

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

Application of electrical resistivity tomography (ERT) for vertical high-density polyethylene (HDPE) membrane detection

At landfill sites, uncontrolled leachate is a serious cause of groundwater and soil contamination at landfills and can occur extensively when there are looploopholesin the vertical HDPE (High-density polyethylene) membrane. For this reason, detecting HDPE membranes is necessary. The conventional electrode running poles approach is limited, it reflects the distribution of resistivity in 2D subsurface profiles, which is difficult to deploy electrodes above vertical HDPE membrane. According to the structural characteristics and field conditions of vertical HDPE membranes, the two-row current and potential (CP) electrode array is proposed to be applied to the testing of vertical HDPE membranes. The forward geoelectric model of the vulnerability was built using pyGimli, and data on 1519 apparent resistivity were acquired. The previous knowledge without the vulnerability was taken into consideration as the constraint condition, and the regional control was added to conduct the inversion, all using the least square approach. The model was used to analyze data on the detection of vertical HDPE membranes in a landfill In Yancheng, and potential flaws were discovered. Results show that the CP electrical measuring device can be efficient, quick, and accurate in the positioning of vertical HDPE membrane hole detection, and it is a cost-effective method. To verify the results, in the vertical HDPE membrane, through the Wenner device, the inversion of the 2D profile, and low resistivity anomalies are detected. This is thought to be through the leachate of leakage of HDPE membrane resistance rate is about 1.8 ohm. The findings demonstrate that the vertical HDPE membrane susceptibility may be located and detected using a CP electrical measuring instrument, which is a practical and efficient approach.

Research on a method for localizing high-density polyethylene membrane leakage based on the wave velocity inversion model

Research on a method for localizing high-density polyethylene membrane leakage based on the wave velocity inversion model

Hydrophilization of Hydrophobic Mesoporous High-Density Polyethylene Membranes via Ozonation.

This work addresses hydrophilization of hydrophobic mesoporous membranes based on high-density polyethylene (HDPE) via ozonation. Mesoporous HDPE membranes were prepared by intercrystallite environmental crazing. Porosity was 50%, and pore dimensions were below 10 nm. Contact angle of mesoporous membranes increases from 96° (pristine HDPE) to 120° due to the formation of nano/microscale surface relief and enhanced surface roughness. The membranes are impermeable to water (water entry threshold is 250 bar). The prepared membranes were exposed to ozonation and showed a high ozone uptake. After ozonation, the membranes were studied by different physicochemical methods, including DSC, AFM, FTIR spectroscopy, etc. Due to ozonation, wettability of the membranes was improved: their contact angle decreased from 120° down to 60°, and they became permeable to water. AFM micrographs revealed a marked smoothening of the surface relief, and the FTIR spectra indicated the development of new functionalities due to ozonolysis. Both factors contribute to hydrophilization and water permeability of the ozonated HDPE membranes. Hence, ozonation was proved to be a facile and efficient instrument for surface modification of hydrophobic mesoporous HDPE membranes and can also provide their efficient sterilization for biomedical purposes and water treatment.

TFC solvent-resistant nanofiltration membrane prepared via a gyroid-like PE support coated with polydopamine/Tannic acid-Fe(III)

Solvent resistant nanofiltration (SRNF) is now a powerful tool for addressing environmental issues. Hence, we report the fabrication of a thin film composite (TFC) membrane comprised of a novel HDPE support, a polydopamine (PDA)/Tannic acid-Fe(III) interlayer and a polyamide (PA) skin layer. In this respect, high density polyethylene (HDPE)-polystyrene (PS)-styrene-ethylene-butylene-styrene (SEBS) blends were formed with different compositions by mixing via a Brabender machine and making films by using a hot press instrument. Next, a solvent extraction technique was employed for extracting the dispersed phase and making the HDPE membranes. The support membrane with optimum properties was coated with a PDA interlayer. A tannic acid-Fe(III) interlayer was also formed on the as-prepared PDA layer so that the hydrophilicity of the support surface was enhanced to form a defect-free PA layer. The modified support was utilized for the fabrication of the PA top layer by using m-phenylene diamine (MPD) and trimesoyl chloride (TMC) monomers. The prepared TFC membrane provided a significant dye rejection ability (99.9% Direct Yellow, 99.7% Methyl Green, 99.2% Rhodamine B, and 96.1% Methyl Orange), extraordinary solvent resistance ability in harsh solvents, and good methanol (MeOH) Flux (2.25 L/m2.h.bar) in SRNF applications. The skin-substrate adhesion strength of the top layer was also evaluated by a back-ward flush operation. It was demonstrated that the interlayer and the skin layer had an excellent adhesion with the support membrane.

Thin film composite solvent resistant nanofiltration membrane via interfacial polymerization on an engineered polyethylene membrane support coated with polydopamine

In this work, a thin film composite (TFC) membrane possessing outstanding properties for solvent resistant nanofiltration (SRNF) membrane application was fabricated. For this purpose, high density polyethylene (HDPE)-polystyrene (PS)-styrene-ethylene-butylene-styrene (SEBS) blends were fabricated in the first step with different compositions by using an internal mixer machine and hot press technique, respectively. Then, the fabrication of a novel HDPE support was conducted by etching the PS phase out of the as-prepared HDPE-PS-SEBS blends through solvent extraction method (Etched HDPE). In the next step, the prepared Etched HDPE membrane support was dipped in a dopamine solution, by which auto-oxidization and self-polymerization of dopamine monomers onto the Etched HDPE membrane supports surface was done, leading to the formation of an ultrathin polydopamine (PDA) layer with a strong chemical binding force. By the formation of the polydopamine layer, hydrophilic functional groups were introduced onto the HDPE membranes surface, causing the attraction of m-phenylenediamine (MPD) monomers onto the membrane surface and the formation of a uniform ultrathin PA top layer. Finally, the TFC layer was formed on the as-prepared membrane supports with different m-phenylenediamine and trimesoyl chloride (TMC) concentrations. The performance and properties of the prepared TFC-PE@PDA membrane was investigated for rejection of different dyes including Reactive Red, Direct Yellow, Methyl Blue, Rhodamine B, Crystal Violet and Methyl Orange in SRNF applications, based on which outstanding separation performance (dye rejections of 99.8, 99.5, 99.2, 98.5, 96.8 and 94.4 for RR, DY, MB, RDB, CV and MO, respectively, under the pressure of 9 bar), methanol flux as high as 1.8 L/m2 h bar along with excellent methanol flux as high as 3.7 L/m2 h bar after Dimethylformamide activation, were obtained. Furthermore, it is noteworthy that an outstanding solvent resistance (dye rejections of more than 99.2, 98.8, 98.5, 97.9, 96 and 93.8% for RR, DY, MB, RDB, CV and MO, respectively, being dipped in Dimethylformamide at 70 °C for 90 days) was also shown by the prepared TFC-PE@PDA membrane.

Suitability of different tests for characterization of the dimpled concrete‐to‐concrete interface

AbstractThe main aim of this study was to assess the suitability of different existing test setups for the mechanical characterization of a dimpled interface obtained by casting concrete against dimpled high‐density polyethylene (HDPE) membrane. Even though this type of interface roughening is widely used, especially for monolithic connections between precast elements, to the best of the authors' knowledge there is no research providing any data regarding its roughness parameters, tension, and shear strength, nor its failure modes. To this end, a two‐fold objective was established for this research: (a) to identify and analyze, from a technical standpoint, the available test configurations for characterizing the mechanical performance of interfaces, and (b) to perform an extensive experimental program devoted to characterizing the mechanical performance of a dimpled HDPE membrane—cast concrete interface. The suitability of each test for reproducing the expected stress state and the actual resistance mechanism was analyzed. Moreover, a comparison between tension and shear tests, including its main advantages and disadvantaged are also presented.

A comparison of CH4, N2O and CO2 emissions from three different cover types in a municipal solid waste landfill

ABSTRACTHigh-density polyethylene (HDPE) membranes are commonly used as a cover component in sanitary landfills, although only limited evaluations of its effect on greenhouse gas (GHG) emissions have been completed. In this study, field GHG emission were investigated at the Dongbu landfill, using three different cover systems: HDPE covering; no covering, on the working face; and a novel material-Oreezyme Waste Cover (OWC) material as a trial material. Results showed that the HDPE membrane achieved a high CH4 retention, 99.8% (CH4 mean flux of 12 mg C m-2 h-1) compared with the air-permeable OWC surface (CH4 mean flux of 5933 mg C m-2 h-1) of the same landfill age. Fresh waste at the working face emitted a large fraction of N2O, with average fluxes of 10 mg N m-2 h-2, while N2O emissions were small at both the HDPE and the OWC sections. At the OWC section, CH4 emissions were elevated under high air temperatures but decreased as landfill age increased. N2O emissions from the working face had a significant negative correlation with air temperature, with peak values in winter. A massive presence of CO2 was observed at both the working face and the OWC sections. Most importantly, the annual GHG emissions were 4.9 Gg yr-1 in CO2 equivalents for the landfill site, of which the OWC-covered section contributed the most CH4 (41.9%), while the working face contributed the most N2O (97.2%). HDPE membrane is therefore, a recommended cover material for GHG control.Implications: Monitoring of GHG emissions at three different cover types in a municipal solid waste landfill during a 1-year period showed that the working face was a hotspot of N2O, which should draw attention. High CH4 fluxes occurred on the permeable surface covering a 1- to 2-year-old landfill. In contrast, the high-density polyethylene (HDPE) membrane achieved high CH4 retention, and therefore is a recommended cover material for GHG control.

MEMBRANE FROM PLASTIC WASTE FOR THE TREATMENT OF CONTAMINATED RIVER WATER

Excessive plastic waste and river water pollution are both never ending environmental problems faced by every country around the world. In this paper, polymeric membrane was synthesized from plastic waste of high density polyethylene (HDPE) type to treat contaminated river water. The plastic waste was grinded into powder of different particle sizes before synthesizing the membrane by sintering method. The membranes were synthesized both with and without the addition of solvents. The heating temperature during membrane synthesis was also being study for membrane performance in terms of percentage of permeate rejection and permeate flux. HDPE membrane produced from average particle size of 270.7±178.6 μm achieved the highest permeate rejection and has highest heating temperature (180ºC). Field Emission Scanning Electron Microscopic (FESEM) analysis showed that the sintered membranes exhibit a porous asymmetric structure. Meanwhile, Fourier Transform Infrared Spectroscopy (FTIR) analysis denote the HDPE membranes in grouped as alkanes and aromatics compounds.

Fabrication and study of fouling characteristics of HDPE/PEG grafted silica nanoparticles composite membrane for filtration of Humic acid

In this study, pure and poly(ethylene glycol) grafted silica nanoparticles (PEG-g-silica NPs) were synthesized using sol–gel method and used to fabricate microporous mixed matrix high density polyethylene (HDPE) membranes via TIPS method. A set of characterization tests including FE-SEM, BSE, EDS, AFM, contact angle, membrane pore size and pure water flux (PWF) were carried out. Furthermore, the governing fouling mechanisms were determined using classic models as well as combined fouling models. In addition, the effect of pre-coagulation with polyaluminium chloride (PAC) on the humic acid (HA) filtration was also investigated. FE-SEM images of synthesized nanoparticles showed that the particles size decreased from 70nm to 35nm by increasing the PEG concentration. It was seen that the water flux of PEG-g-silica NPs/HDPE membrane was about 7.45 times higher than that of pure HDPE membrane. Also, the contact angle test confirmed reducing of membrane contact angle to 96 in the presence of PEG-g-silica NPs. Bubble point measurements showed that the largest pore diameter of the membranes had no discernable change after embedding nanoparticles. The results obtained from the fouling study indicated an excellent performance in mitigating fouling for nanocomposite membranes. Also, it was found that pre-treatment with PAC can significantly mitigate fouling and improve humic acid removal.

Influence factor analysis of the electricity-dipole method for landfill leakage detection on HDPE membrane

Experiments were performed to investigate the role of electricity-dipole method in landfill leakage detection on high-density polyethylene (HDPE) membrane in terms of the leakage size, ply mode of leachate drainage layer (LDL), and water or leachate invasion. The result indicates that in a dry environment the leakage size equal to or greater than 1.0 cm can be detected precisely. For ply mode of LDL, the mono-sized layer is beneficial to the HDPE leakage detection relative to multi-sized gravel (i.e., coarse-sized gravel in the bottom and fine-sized gravel on the top of the LDL). For the invasion of water, the leakage size equal to or greater than 0.5 cm could be detected precisely. In addition, the influence of electrode above the HDPE membrane on the potential distribution around the leakage is significant. The detectable range close to the electrode above HDPE membrane is smaller than that away from the electrode above the HDPE membrane. The leachate-invaded LDL is beneficial to leakage detection relative to water-invaded or dry LDL. But in field application, sprinkling the LDL surface with water is enough to obtain detection data for precise leakage location.

Experimental research on the high-density polyethylene anti-permeable membrane of waste-water pools

Since a high-density polyethylene membrane has good mechanical properties and stable chemical properties, it is widely used in all kinds of anti-permeable layers. But for a sewage pool of a drilling engineering in the western desert oil field, it is not only facing a high temperature and drying environment, but also quite a complex drilling fluid composition. Yet an experimental study system on application has not set up in China. According to the working environment of the high-density polyethylene membrane, a series of aging tests are carried out in the paper. Measured the change value of the high-density polyethylene membrane, mechanical properties are expressed directly the aging properties of high-density polyethylene membranes.

Effect of TiO2 nanoparticles on structure and properties of high density polyethylene membranes prepared by thermally induced phase separation method

Polyethylene/TiO2 membranes were fabricated via thermally induced phase separation (TIPS) method. A set of characterization tests including FE‐SEM, EDX, XRD, DSC, TGA, DMA, mechanical test and relative pure water flux for characterization of membranes were carried out to investigate the effect of TiO2 nanoparticles on membrane properties. The results of EDX, XRD and TGA analyses confirmed the presence of TiO2 nanoparticles in the polymer matrix. The results of DSC analysis revealed that the melting point as well as the crystallinity of the membranes increased slightly with increasing TiO2 content. However, the glass transition temperature of the membranes was not affected by the presence of particles. Addition of nanoparticles also increased storage modulus, loss modulus and tensile strength at break of the membranes due to the stiffness improvement effect of inorganic TiO2. Finally, it was observed that incorporation of the nanoparticles improved pure water flux of the membranes. Copyright © 2015 John Wiley & Sons, Ltd.

Preparation, characterization and fouling analysis of ZnO/polyethylene hybrid membranes for collagen separation

In this study, high density polyethylene (HDPE) membranes embedded with ZnO nanoparticles were fabricated via thermally induced phase separation (TIPS) method. A series of tests including FESEM, XRD, TGA, AFM, contact angle measurement, pure water flux, porosity and mean pore radius were performed for characterization of membranes. FESEM images showed that the membranes had leafy structure indicating solid–liquid phase separation mechanism. The results of XRD and TGA analysis confirmed the presence of ZnO nanoparticles in the polymer matrix. AFM images showed that the surface roughness of ZnO embedded membranes were higher than that of neat HDPE membrane. Pure water flux as well as surface hydrophilicity of membranes improved as the ZnO content increased. In addition, the fouling behavior of membranes was investigated by filtration of collagen protein solution. The governing fouling mechanisms of membranes were also investigated using classic models as well as combined fouling models. The results showed that for all membranes the best fit of the data occurred with the cake filtration-complete blockage model (CFCBM). Moreover, the deviation between experimental data and CFCBM prediction decreased by increasing the content of ZnO.

Analysis of fouling mechanisms in TiO2 embedded high density polyethylene membranes for collagen separation

In this study, the fouling behavior of TiO2–polyethylene hybrid membranes was analyzed. Initially, high density polyethylene (HDPE) membranes embedded with TiO2 nanoparticles were fabricated via thermally induced phase separation (TIPS) method. FESEM images showed that the membranes had leafy structure indicating solid–liquid phase separation mechanism. The results of XRD analysis confirmed the presence of TiO2 nanoparticles in the polymer matrix. AFM images showed that the surface roughness of TiO2 embedded membranes were higher than that of neat HDPE membrane. Pure water flux of membranes improved as the TiO2 content increased. The fouling behavior of membranes was investigated by filtration of collagen protein solution. The governing fouling mechanisms of membranes were also investigated using classic models as well as combined fouling models. The results showed that the best model fitted into the experimental data for 0.50, 0.75 and 1.0wt.% TiO2 embedded HDPE membranes was the cake filtration model. For neat and 0.25wt.% TiO2 embedded membranes, however, cake filtration-complete blockage model was in good agreement with the experimental data. Moreover, addition of TiO2 nanoparticles increased reversible portion of fouling.

Grafting of molecularly imprinted polymer to porous polyethylene filtration membranes by plasma polymerization

An application of plasma-induced grafting of polyethylene membranes with a thin layer of molecularly imprinted polymer (MIP) was presented. High-density polyethylene (HDPE) membranes, "Vyon," were used as a substrate for plasma grafting modification. The herbicide atrazine, one of the most popular targets of the molecular imprinting, was chosen as a template. The parameters of the plasma treatment were optimized in order to achieve a good balance between polymerization and ablation processes. Modified HDPE membranes were characterized, and the presence of the grafted polymeric layer was confirmed based on the observed weight gain, pore size measurements, and infrared spectrometry. Since there was no significant change in the porosity of the modified membranes, it was assumed that only a thin layer of the polymer was introduced on the surface. The experiments on the re-binding of the template atrazine to the membranes modified with MIP and blank polymers were performed. HDPE membranes which were grafted with polymer using continuous plasma polymerization demonstrated the best result which was expressed in an imprinted factor equal to 3, suggesting that molecular imprinting was successfully achieved.

Hydrophilic modification of HDPE microfiltration membrane by corona-induced graft polymerization

Hydrophilic modification of high-density polyethylene membrane was performed with the introduction of peroxide onto the membrane surface by corona discharge treatment, followed by graft polymerization with acrylic acid. The surface graft polymerization was confirmed by attenuated total reflection-infrared and X-ray photo spectroscopy. Surface hydrophilicity was investigated by measuring the contact angles and moisture adsorption of the modified membrane. The results indicated that the modified membrane showed a significant increase in hydrophilicity. And water flux of the film increased from 102 L/m2 h of the virgin film to 200 L/m2 h of the grafted film, while the bovine serum albumin solution flux of the membrane increased from 43 L/m2 h of the virgin film to 98 L/m2 h of the modified membrane.

Degradação polimérica de membrana impermeabilizante de polietileno de alta densidade usada em tanques de armazenamento de vinhaça

High-density polyethylene (HDPE) water-proof membranes are used as coatings in vinasse (leachate from sugar cane) storage tanks. The leachate is pumped into the tanks at temperatures of 80-90 °C. Due to these high temperatures and acidity of the waste, these membranes can be degraded, cracked and then loose the function for which they have been designed. This may cause contamination of the soil and groundwater. This study evaluated the effect of vinasse in HDPE membranes after 4 months of exposure in a controlled environment. An aggressive, alkaline pH liquid (sodium hydroxide) was also used. The objective was to evaluate the membrane resistance in contact with acidic and alkaline residues. Physical and mechanical tests, measurement of the carbon black content and thermo gravimetric analysis (TGA) were used to determine degradation of polymer membranes after chemical immersion. While sodium hydroxide resulted caused only minor changes in the physical properties, vinasse induced a thickness change of 7.8%. With immersion in vinasse, an average decrease in strength and deformability (yield) of 34% and 23.5% were measured, respectively. The stiffness increased by 7.8% (average) and the tear strength decreased by 2.7% (average).

Effect of rainfall on the diurnal variations of CH4, CO2, and N2O fluxes from a municipal solid waste landfill

This paper presents the results of a field investigation into the effect of rainfall on the diurnal variations of CH4, CO2, and N2O fluxes at three different sites in a landfill. The three sites were all net sources of CH4, CO2, and N2O emissions ranging from 4.7–796mg CH4–Cm−2h−1, 131–811mg CO2–Cm−2h−1, and 90.6–2209μg N2O–Nm−2h−1. CH4 and N2O were generated by anaerobic digestion of waste and by nitrification and denitrification in the cover soil, respectively. Installation of an HDPE (High Density Polyethylene) membrane cover at landfill Site 1 was very effective in controlling CH4 emissions, and the CH4 fluxes at that site were 40–50 times lower than those at Site 2 and Site 3. For 36h following a rainfall event, both CH4 and N2O emissions were significantly correlated with moisture content of the cover soil at the two landfill sites without HDPE membrane cover (p<0.05). When CH4 and N2O fluxes were expressed as CO2-equivalent (CO2-e) emissions, CH4 emissions dominated in the three gases after rainfall (96.1% CO2-e emissions) and could be expressed by the following equation: YCH4=988.7+41.1X(soil moisture content)−32.2X(soil temperature) (R2=0.73, p<0.05).