Waste Polyethylene Research Articles

Study and Application of Compatibility of Waste Polyethylene-Modified Asphalt

The storage stability of polyethylene (PE)-modified asphalt was investigated. The experimental results of this paper show that the storage stability of PE-modified asphalt is poor, and it is difficult to solve the compatibility problem between PE and base asphalt by adding stabilizer. In this paper, the study and application of the rubber plastic composite method to improve the compatibility of PE and base asphalt was investigated. The experimental result shows that styrene-butadiene-styrene block copolymer (SBS) could be melted with waste PE with a twin-screw extruder to prepare PE-SBS modifier. The PE-SBS modified asphalt prepared is stable in storage. The compatibility of PE and base asphalt is improved effectively by rubber plastic composite method. Infrared spectra show that PE-SBS is mainly formed by physical action.

Preparation and performance of autoclaved aerated concrete reinforced by dopamine-modified polyethylene terephthalate waste fibers

• Waste granite powder and polyethylene terephthalate (PET) fiber were used to prepare autoclaved aerated concrete (AAC). • A simple and efficient process was used to improve the interface bonding of the composites. • The flexural and compressive strengths of the AAC with the modified waste PET fiber increased by 37.2% and 12.7%, respectively. The low tensile and flexural strengths make autoclaved aerated concrete (AAC) susceptible to cracking and damage during transportation and service. This study investigated the use of waste polyethylene terephthalate (PET) fiber as AAC reinforcement, which is a byproduct from the textile industry. Meanwhile, waste granite powder from stone plate processing byproducts was used as a siliceous material in the preparation of fiber-reinforced AAC composites. The waste PET fibers were modified by dopamine hydrochloride to improve the interfacial adhesion between the fibers and the AAC matrix. Results showed that the AAC blocks with 0.1 wt% PET fiber (1 mm in length and 18 μm in diameter) increased the compressive and flexural strengths by 6.0 % and 28.4 %, respectively. By adding 2 g/L dopamine-modified waste PET fiber, the compressive and flexural strengths of the blocks were further increased by 12.7 % and 37.2 %, respectively. The PET fibers were characterized using water contact angle test, SEM, FTIR, XPS, and TG analyses. It was confirmed that the amino and hydroxyl groups were grafted onto the modified fiber surface, leading to improved hydrophilicity and reactivity of the fibers and thus enhanced interfacial bonding between the fibers and the AAC matrix.

Recycling of Waste Polyethylene Terephthalate (PET) into Insulating Wall Panels for Building Industry

The administration and management of waste is one of the major issues confronting the advanced society and is not fairly constrained to plastics. The squandering or waste generated annually is by and large a claim in Pakistan. Reusing plastic is required to support the environment. The wall panels that are utilized in interiors are made up of Polyvinyl chloride (PVC) which is harmful and there are few chances to diminish the poisons from it. Moreover, they are not perfect insulators and are very expensive. The work aims to utilize plastic squander into wall panels made of reusing Polyethylene Terephthalate (PET) which are aesthetically pleasing, economical, easy to maintain and of high quality. The method incorporates case studies and surveys to find out the finest manufacturing and fabricating process. The experiment phased in product specification along with drawings, rendering, prototyping and finally recycling plastic into the final product. The conductivity of the material is raised by using blisters with a silver coating which raised from 5% to 10% and a vacuum is also created between the panels. The compressive strength is tested which is 80.5 MPa. If the product is made on a large scale, it will help in reducing plastic waste.

Performance evaluation and optimization of vacuum pressure swing adsorption cycle for CF4 recovery using activated carbon

The emission of CF4 exacerbates the climate change and hinders the development of related industries, and the adsorption method for CF4 recovery is a response method with multiple benefits. However, there is a lack of research works on performance evaluation, optimization of recycling cycle and decision of the working condition. In this paper, the activated carbon converted from waste polyethylene terephthalate (PET) is used as the adsorbent, and the adsorption data of CF4 are fitted by various models of adsorption isotherm. A numerical model of vacuum pressure swing adsorption (VPSA) cycle and the corresponding evaluation indexes of cycle performance are proposed. The relationship between working parameters of the VPSA cycle and the cycle performance under constant and variable efficiency of working units is studied. The Pareto optimal solution set of the cycle within a specified range of working parameters is obtained by the optimization algorithm developed with the indexes of cycle performance as the objective. The optimal cycle scheme under the determined weight of cycle performance is found by different decision methods. The results show that the Toth model fits the adsorption data best, and the value of coefficient of determination (R2) is greater than 0.99. The competitive relationship between exergy efficiency and purity (or recovery rate) under variable efficiency of working units is more complicated. The work consumption of the vacuum pump is an important determinant of cycle energy consumption. The purity, recovery and exergy efficiency of VPSA cycle under balanced optimal solution with constant efficiency of working units are 0.616, 0.726 and 0.064, and the adsorption pressure and regeneration pressure are 157819.96 Pa and 6057.96 Pa, respectively. However, the cycle performance of variable efficiency of working units is worse in the optimal scheme under certain weight of cycle performance.

Kevlar-like Aramid Polymers from Mixed PET Waste.

This work describes the synthetic approaches, spectroscopic and thermal characterization of aramid polymers prepared from waste polyethylene terephthalate (PET) via sustainable and scalable processes. Direct depolymerization of PET with aliphatic diamines under melt conditions resulted in decomposition without substantial formation of any aramid polymer. The Higashi–Ogata methodology or direct polycondensation of terephthalic acid (TPA) derived from PET waste and p-phenylenediamine, resulted in oligomerization and formation of aramids with a low degree of polymerization. The highest molecular weight polymers were obtained via the acid chloride of TPA, the traditional method. A proprietary solvent enabled the dissolution of most polymers and subsequent size exclusion chromatography analysis in the same solvent. We emphasize that although the soluble polymer compounds are prepared via the traditional route, they are novel. The apparent molecular weights of the soluble polymers ranged between 10–35 kDa (Mn) and 28–81 kDa (Mw). All analogues were prepared with commercially available diamines and diamine combinations. The obtained solid powders were dissolved in D2SO4 and analyzed spectroscopically to qualitatively evaluate the degrees of polymerization, while the solids were characterized via thermogravimetric analysis and differential scanning calorimetry. Many reaction conditions were employed to improve the solution polycondensation reaction, and it was found that addition of pyridine (2 eq) to the NMP reaction medium was crucial in preventing the precipitation of the polymer. Contrary to conventional wisdom, CaCl2 did not play a crucial role in the molecular weight increase of the polymer when oxydianiline was used. Our data indicated that the temperature and absence of CaCl2 provided a boost in molecular weight. Both room temperature and 0 °C reactions generated similar polymers as suggested by nuclear magnetic resonance; however, the cold conditions enhanced gel formation, an important attribute in the future processing of these materials to obtain fibers. All analogues had a high degradation temperature at 5 and 10% weight loss (5% and T10%), above 400 °C, along with high percent char values. A glass transition (Tg) was not detected in any of the analogues prepared.

Oxidative degradation of UV-irradiated polyethylene by laccase-mediator system

Polyethylene (PE) is one of the most widely used plastics. However, the chemical inertness, inefficient recycling, and random landfilling of PE waste have caused serious pollution to the natural environment. In this study, a series of laccase-mediator systems (LMS) were constructed by combination of two laccases from Botrytis aclada (BaLac) and Bacillus subtilis (BsLac) with three synthetic mediators (ABTS, HBT, and TEMPO) to oxidize LDPE films (UVPE) pretreated with high-temperature UV irradiation. Scanning electron microscopy showed aging phenomena such as etching, fragmentation, and cracking on the surface of the UVPE films after LMS incubation. The FTIR results showed that LMS-UVPE added new oxygen-containing functional groups such as -OH, -CO, and CC. High-temperature gel chromatography confirmed that the average reduction in weight-average molecular weight (Mw) was approximately 40% for the BaLac experimental group. GC-MS analysis showed the presence of oxygen-containing products, such as aldehydes, ketones, and alcohols, in the reaction mixture. To verify the oxidation process UVPE degradation by LMS, we inferred three possible pathways by combined analysis of the oxidation products of LMS on UVPE and model substrates oleic acid and squalene.

Biomass and low-density polyethylene waste composites gasification: Orthogonal array design of Taguchi technique for analysis and optimization

This modeling study explores and optimizes the performance of the gasification of a rice husk and low-density polyethylene waste composite utilizing an orthogonal array design of a Taguchi technique. This modeling study uses a signal to noise ratio analysis to optimize the gasification of rice husk and low-density polyethylene waste composite and utilizes an analysis of variance approach to identify the most important factors contributing to the process. It is shown that the composition ratio of rice husk and polyethylene waste contributes significantly to the gasification performance. Increasing composition ratio of rice husk and polyethylene waste improves hydrogen concentration, decreases carbon dioxide concentration and enhances carbon monoxide concentration. Energy efficiency is enhanced and normalized carbon dioxide emission is improved by increasing composition ratio of rice husk and polyethylene waste. The gasification of rice husk and low-density polyethylene waste composite is efficient (total energy efficiency of 77.6%) and clean (normalized carbon dioxide emission of 2.1 g/mol, based on the composite entering the system) at its multi-objective optimum conditions. The research results support the development of a system for gasification of biomass and plastic waste composites utilizing orthogonal array design of a Taguchi approach.

Study on the Characteristics of Non-catalytic Pyrolysis of Polypropylene(PP), Polyethylene(PE) Waste Plastics

Study on the Characteristics of Non-catalytic Pyrolysis of Polypropylene(PP), Polyethylene(PE) Waste Plastics

Pyrolysis of High-Density Polyethylene Waste Plastic to Liquid Fuels—Modelling and Economic Analysis

Recycling of waste plastics has become vital due to the threat to the environment the huge piles of those wastes represent, with research revealing High-Density Polyethylene (HDPEs) as the most dominant waste plastics. Because of their dominance and significant environmental impact, this paper reports the economic potential of recycling HDPE waste plastic into liquid fuels via pyrolysis. A risk and benefit assessment are presented to highlight whether the process has reasonable potential prior to the analysis of its corresponding finances. Aspen HYSYS simulation models were used as the basis for the analysis. From this, preliminary cost estimations for the net present value (NPV) of the process, its economic viability, were determined. It is shown that 100 kg/h of waste is not financially sustainable. Retailing the fuel product at a competitive price of £60/barrel would ultimately bankrupt the business. This is a consequence of the extremely high production cost of £198.40/barrel inducing the complete absence of profitability. Furthermore, the operating expenditure is found to be the root cause of the consequential financial decline, totalling £1.46 million per annum. The two most detrimental expenditures for the production cost of the pyrolysis oils were the wages of the skilled operating labour and higher utility fees incurred by the extreme temperature conditions. In addition, an unrealistically optimistic sale price of £300/barrel was also applied to ascertain a positive economic incentive. Even with the increased retail price, the process’ profits are negligible and further highlight the detrimental effect of the undesirably high operational expenditures, once more signifying that the process should not commence in its current state. However, executing such a project in developing countries such as Sierra Leone, Senegal, or Kenya where utilities and manpower, among other operational components, are cheaper, is believed to complement the immense opportunity underlying pyrolysis oil production regarding production quantity and quality.

Rheological properties of asphalt binder modified with waste polyethylene: An interlaboratory research from the RILEM TC WMR

Significant volumes of waste materials such as plastics is generated every year worldwide with a potentially harmful impact on the environment. At the same time, the demand for asphalt modifiers has seen an increase over the year with consequent higher costs for these types of additives. Therefore, combining large amounts of available waste plastics with asphalt binder as an extender or modifier would potentially improve the paving material properties while limiting the disposed waste. While several rheological studies have been performed in the past, they were restricted to single research efforts hindering a consistent comparison among the valuable results of these investigations. For this reason, the Task Group 1 of the RILEM Technical Committee 279-WMR established a research activity with 11 international institutions to conduct interlaboratory research to evaluate the possibility of using waste polyethylene (PE) as an additive in asphalt binder. The study addressed the combined impact of PE materials and experimental conditions on the rheological properties of asphalt binder. For this purpose, conventional tests (penetration value, softening point temperature, and Fraass breaking point temperature) and the linear viscoelastic characterization using the Dynamic Shear Rheometer (DSR) were adopted. An unaged pen grade 70/100 neat binder was selected as the reference binder; PE-pellets and PE-shreds, produced from the recycled waste polyethylene materials, were used as the polymer additives. A single content (5%) of PE-pellets and PE-shreds was used to blend the PE material with the reference binder (95%) and prepare the two PE modified binders. Results indicate that the use of plastic modifiers leads to an overall higher complex shear modulus and softening point temperature while decreasing the penetration value. Higher dispersion in the results, especially in phase angles, was observed for blended binders at high temperatures. The PE modified binders exhibited poor reproducibility among laboratories and a low level of repeatability. Such a scatter in the data could result from an uneven dispersion of plastic material at high temperatures. In contrast, plastic shapes and batches appeared to have a limited impact. Three different rheological behaviors, neat binder, modified binder, and complex modified binder, were visually identified among the interlaboratory results and based on a simple statistical analysis of variance. Further analysis of the data suggested that the Glover Rowe (G-R) parameter can be used as a sensitive tool to classify the rheological behaviors of PE modified binders. Further experimental evaluation on specific testing conditions, such as measurement gaps of DSR at high temperatures, is recommended to advance the understanding of their influence on the rheological behavior of PE modified binders.

Green synthesis of metal-organic framework MIL-101(Cr) – An assessment by quantitative green chemistry metrics

MIL-101(Cr) is a metal–organic framework with high surface area and porosity synthesized for environmental applications, even though conventional synthesis uses toxic chemicals such as N, N-dimethylformamide (DMF) or hydrofluoric acid (HF). Therefore, we present a green evaluation of a novel synthesis that avoids adding any toxic modulator and uses waste polyethylene terephthalate (PET) as a source of the organic linker terephthalic acid (H2BDC). As a result of this strategy, MIL-101(Cr)-PET had a similar crystalline structure to conventional synthesized MIL-101(Cr)-BDC. Nitrogen gas adsorption measurements were applied to analyze textural properties; MIL-101(Cr)-PET presents a lower BET surface area (1852 m2/g) than MIL-101(Cr)-BDC (3431 m2/g). However, MIL-101(Cr)-PET exhibited similar toluene adsorption performance (42 mmol/g) than MIL-101(Cr)-BDC (40 mmol/g). A green assessment of MIL-101(Cr)-BDC synthesis using DOZN™ green chemistry evaluator revealed that the major impacts are in the Green Chemistry Principles of Prevention, Less Hazardous Chemical Synthesis, Safer Solvents and Auxiliaries, and Inherently Safer Chemistry for Accident Prevention due to the use of DMF in the activation process. Based on the environmental score, a reduction of 50 % in impacts on the 12 Green Chemistry Principles was achieved when PET was used as a source of H2BDC in addition to the elimination of nitric acid as a modulator and the use of non-toxic solvents. The outcomes of this study show that the greener synthesis of MIL-101(Cr) has the potential to become a competitive material for toluene adsorption at diluted concentrations for indoor air quality applications.

Characteristics and polyethylene biodegradation function of a novel cold-adapted bacterial laccase from Antarctic sea ice psychrophile Psychrobacter sp. NJ228

Biotreatment of polyethylene (PE) waste is an emerging topic in environmental remediation; in particular, the degrading enzymes requires further exploration. This study described a novel cold-adapted laccase (PsLAC) from an Antarctic psychrophile and characterized its PE-degradation ability. Homology modeling revealed that PsLAC possessed a typical bacterial laccase catalytic structure and unique cold adaptation structural characteristics such as few hydrogen bonds. Recombinant PsLAC (rPsLAC) retained 54.3% residual activity at 0 ℃ and presented increased Km values at low temperatures and a relatively high kcat value (42.65 s−1). Collectively, these factors help resist cold stress. rPsLAC possessed substantial salt tolerance at 1.5 M NaCl, with 119.80% activity, and Cu2+ enhanced its activity to 127.10%. PE-degradation experiments indicated that 13.2% weight was lost, and the water contact angle was decreased to 74.6°. Polar functional groups such as carbonyl and carboxyl groups on PE surface were detected in Fourier transform infrared spectroscopy; X-ray diffraction exhibited that crystallinity reduced by 25%. Enormous damage to PE surface and interior was observed via scanning electron microscopy. Overall, PsLAC, with its unique cold-adapted catalytic structure and biochemical characteristics, could supplement the diversity of sources and properties of bacterial laccases and ensure PE-degradation with a novel cold-adapted enzyme resource.

Laminated PET-based membranes with sweat transportation and dual thermal insulation properties

Wearable polyester fiber materials with excellent sweat transportation and enhanced thermal management properties have received increasing attention in functional materials and energy saving fields because of not only for wearing comfort but also for developing advanced energy-saving materials. Herein, this work presents an effective and sustainable strategy for fabrication of laminated CNTs-MnO2 nanowires/PET fibers@Ag (CMPFA) membranes using waste polyethylene terephthalate (PET) fabric, manganese dioxide (MnO2) nanowires, carbon nanotubes (CNTs) and silver nanoparticles as building blocks through electrospinning, vacuum filtration and subsequent magnetron sputtering processes, as well as its application in personal thermal management. The results indicated that simulated sweat on the PET fibers@Ag side can penetrate quickly into the CNTs-MnO2 nanowires side within 2.4 s, implying the excellent sweat transport properties of laminated CMPFA membranes. More importantly, the synergistic thermal management properties can be obtained via infrared radiation and absorb sunlight. Compared with bare PET fibers membranes, the laminated CMPFA membranes exhibited excellent thermal insulation properties. The surface temperature of laminated CMPFA membranes is 11.9 °C higher than that of bare PET fibers membranes after 50 s of simulate sunlight exposure. In addition, the laminated CMPFA membranes show antibacterial properties, breathability, and water vapor permeability, which is beneficial to improving the comfort of wearer. This study shows that the fabrication of flexible wearable laminated membranes for personal thermal management application can be extended for the fabricated of other waste plastic based-materials with controlled structures and desired functions for various applications.

Photoelectrochemical Catalysis of Waste Polyethylene Terephthalate Plastic to Coproduce Formic Acid and Hydrogen

Photoelectrochemical Catalysis of Waste Polyethylene Terephthalate Plastic to Coproduce Formic Acid and Hydrogen

Catalytic Pyrolysis of Waste Polyethylene Using Combined CaO and Ga/ZSM-5 Catalysts for High Value-Added Aromatics Production

Catalytic Pyrolysis of Waste Polyethylene Using Combined CaO and Ga/ZSM-5 Catalysts for High Value-Added Aromatics Production

A recyclable and regenerated aerogel membrane derived from waste plastic for emulsion separation

Waste polyethylene (PE) poses potential risks to the environment and humans, because of its durability, non-biodegradability, and meager recyclability rate. As a resource recycling strategy, functional waste PE-derived materials could significantly promote environmental sustainability and public health by reducing waste PE. In this work, a hydrophobic aerogel membrane from waste PE plastic was fabricated by combining the swelling, solvent extraction, and followed by freeze-drying processes. The characterization results indicated that the obtained aerogel membrane exhibits unique ultra-light properties with rough and porous surfaces, which can enhance the oil/water separation selectivity and membrane flux. The hydrophobic PE aerogel membrane could realize traditional water-in-oil emulsion separation with separation efficiencies as high as 98.75 % and permeating flux up to 1726 L m-2 h-1. After 50 cycles, the separation flux remained over 1700 L m-2h-1, indicating its good recycling ability and durability. Moreover, it maintains excellent emulsion separation capability in harsh environments, including acid, alkali, and concentered salt. Also, the used PE aerogel membrane could be further converted into the new one to achieve a beneficial mode of waste closed-loop recycling.

Dry Addition of Recycled Waste Polyethylene in Asphalt Mixtures: A Laboratory Study.

The circular use of resources (i.e., reuse and recycling of materials) aiming for zero waste is also gaining increasing attention in pavement engineering. In this regard, the possible use of waste plastics in asphalt materials is of strategic importance since a considerable amount of plastic waste from construction and demolition waste and municipal solid waste is generated every year. Given this background, this experimental study aimed to investigate the feasibility of recycling waste polyethylene (PE) into asphalt mixtures. For this purpose, the dry addition of plastic shreds was evaluated to overcome the drawbacks observed in a previous interlaboratory research on PE-modified bituminous binder (i.e., instability/inhomogeneity of blend as well as the need for PE grinding). A comparative laboratory study was carried out on dense graded asphalt mixtures containing different amounts of waste plastics (i.e., 0%, 0.25%, and 1.5% by weight of the mixture). The selected asphalt mixes were investigated in terms of workability, linear visco-elastic characteristics, stiffness, strength, resistance to permanent deformation, and moisture sensitivity. Overall, the experimental findings show that the mixes prepared with the dry addition of plastic wastes were able to guarantee almost the same workability and moisture resistance as the reference material while leading to enhanced performance in terms of stiffness and permanent deformation resistance, with better responses for the higher investigated PE dosage.

Physical and Mechanical Properties Analysis of Wood-waste Composite Panels

The timber industry takes an important place in our modern life, and there has been an increased interest in it for a long time, especially in industrially developed countries. The concerns of the environmental organization regarding the plant wealth preservation have caused scientific trends to search for sources or industries that can achieve acceptable alternatives to natural wood. The materials in this article are related to industrial timber manufacturing of greenhouse wood waste, low density polyethylene and non-standard joinery waste. Moreover, panel samples made from the above materials were briefly subjected to tests as well as tested by fresh and salt water absorption.The density calculation results for all samples have shown the possibility of obtaining a wide range of wooden planks from the lightest to the heaviest ones, depending on the type of filler used. Additionally, the conducted research has shown the possibility of producing artificial wood panels made from the studied materials with good quality and fully satisfactory physical and mechanical properties.

Biocomposite production from waste low-density polyethylene sachets and Prosopis africana pods biomass residue

Plastic litter has become a major concern in solid waste management in recent times due to the adverse effect on the environment. In most developing countries, low-density polyethylene (LDPE) waste bags and sachets constitute a significant portion of plastic wastes that are generated daily, leading to an unnecessary environmental burden that needs to be addressed. In this study, we report the use of Prosopis africana pod particles as fillers in LDPE matrix (obtained from waste plastic sachets) for biocomposite production. Biocomposites were produced from 150µm average filler size for 10, 20, 30 wt% filler contents, using hand lay-up method. The compression, flexural, impact, and tensile strengths; water absorption and the biodegradability characteristics of the prepared biocomposites were determined using ASTM standards. In comparison with the control sample, the prepared biocomposites samples exhibited 103% improved impact strength of 34.3 J and better resistance to deformation (flexural modulus of 348.9 N/mm2; Young’s modulus of 237.9 N/mm2) at 30 wt % filler content. Biocomposite sample with the 10 wt% gave the highest tensile strength of 8.3 N/mm2. Scanning Electron Microscopy (SEM) analysis of the fractured sample shows good adhesion in the matrix. Findings from this work indicate that valorization of LDPE waste sachet and prosopis pods agricultural residues can be a value-addition, affordable waste management method for producing biocomposites towards indoor applications.

Upcycling of waste polyethylene and cement kiln dust to produce polymeric composite sheets using gamma irradiation

Cement kiln dust (CKD) is a residue produced during the manufacture of cement that contains hazardous solid waste of high toxicity that affects the environment and public health. In this study, the possibility of using CKD as a filler in the plastic and rubber industry was studied. The effect of CKD concentration and gamma irradiation dose on the mechanical and physico-chemical properties of the composite containing waste polyethylene/devulcanized rubber/EPDM rubber (named blank) was investigated. Different concentrations of CKD, namely 10, 15, 20, and 30 phr (part per hundred part of composite), were used. The results indicated that this composite (blended with CKD) properties were improved. The most significant improvement was achieved by using CKD concentration of 20 phr at the dose of 100 kGy of gamma irradiation. These findings were demonstrated by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis.Graphical abstract