Recycled Polyethylene Terephthalate Research Articles

Vendor Managed Inventory (VMI) Implementation in Recycled PET Preform for The Beverage Industry

The beverage industry is a company that is focused on producing mineral water in Polyethylene Terephthalate (PET) bottles. PET bottles serve as the primary packaging choice in the beverage industry, making the use of preforms as a material for bottles unavoidable. On the other hand, the public is more aware of using sustainable materials. Adapting market awareness, the company shifted from virgin material to recycled material. Due to the significant initial investment, the company has decided on a single supplier strategy for recycled PET preform suppliers. This policy forces the company to manage the supplier to meet the company’s delivery accomplishment target. Currently, in the management of beverage found in the industry, the supplier only reaches 50% of delivery accomplishments, whereas the company target is 90%. The beverage industry strived for a revolution, so the company’s target was achieved. The vendor managed inventory method is implemented in this study to create a new revolution for PET preform suppliers, a new replenishment system. After the implementation of Vendor Managed Inventory (VMI), there has been an improvement, reaching 95% in delivery accomplishment. The adoption of vendor managed inventory ensures the attainment of the company’s objectives.

Recycling of polyethylene terephthalate to bismuth-embedded bimetallic MOFs as photocatalysts toward removal of cationic dye in water

Our study presents a sustainable approach to fabricating efficient photocatalytic metal–organic frameworks (MOFs) by recycling polyethylene terephthalate (PET) waste from bottles. Through chemical depolymerization, recycled terephthalic acids (BDCs) obtained from PET waste were coordinated with copper (Cu) and nickel (Ni) to prepare a bimetallic Ni/Cu-MOF. After exploring various Ni:Cu ratios (1:3, 2:3, and 3:3), we determined that the 2:3 ratio represents the optimal metal combination (degradation efficiency 50–60% under direct sunlight). Subsequently, we integrated bismuth oxyiodide (BiOI) into the Ni/Cu-BDC MOF, yielding Ni/Cu-MOF@BiOI heterostructures. Thorough structural characterization via scanning electron microscopy and X-ray diffraction confirmed the morphology and composition of the prepared materials. Assessing the photocatalytic performance against methylene blue (MB) degradation in water under solar irradiation, we systematically analyzed operational parameters such as pH, catalyst dosage, MB concentration, and irradiation time. Ni/Cu-MOF@BiOI heterostructures exhibited exceptional efficiency, degrading 99% of MB under sunlight in four hours. Our research presents a sustainable method for the synthesis of photocatalysts using recycled PET waste, along with optimized operational parameters for enhanced catalytic efficiency. This approach combines green synthesis, material hybridization, and thorough analysis, contributing significantly to sustainable materials for pollutant remediation.

The Design of a Sustainable Industrial Wastewater Treatment System and The Generation of Biohydrogen from E. crassipes.

Water scarcity is a significant global issue caused by the prolonged disregard and unsustainable management of this essential resource by both public and private bodies. The dependence on fossil fuels further exacerbates society's bleak environmental conditions. Therefore, it is crucial to explore alternative solutions to preserve our nation's water resources properly and promote the production of biofuels. Research into the utilization of E. crassipes to remove heavy metals and generate biofuels is extensive. The combination of these two lines of inquiry presents an excellent opportunity to achieve sustainable development goals. This study aims to develop a sustainable wastewater treatment system and generate biohydrogen from dry, pulverized E. crassipes biomass. A treatment system was implemented to treat 1 L of industrial waste. The interconnected compartment system was built by utilizing recycled PET bottles to generate biohydrogen by reusing the feedstock for the treatment process. The production of biological hydrogen through dark fermentation, using biomass containing heavy metals as a biohydrogen source, was studied. Cr (VI) and Pb (II) levels had a low impact on hydrogen production. The uncontaminated biomass of E. crassipes displayed a significantly higher hydrogen yield (81.7 mL H2/g glucose). The presence of Cr (IV) in E. crassipes leads to a decrease in biohydrogen yield by 14%, and the presence of Pb (II) in E. crassipes leads to a decrease in biohydrogen yield of 26%. This work proposes a strategy that utilizes green technologies to recover and utilize contaminated water. Additionally, it enables the production of bioenergy with high efficiency, indirectly reducing greenhouse gases. This strategy aligns with international programs for the development of a circular economy.

Progress in 3D printing of recycled PET

Filaments from blends of post-industrial, low-quality recycled poly(ethylene terephthalate) (RPET) and ethylene-butyl-acrylate-glycidyl-methacrylate (EBA-GMA) were extruded with different EBA-GMA contents, then specimens were 3D-printed by fused filament fabrication technology. It has been demonstrated that, when 0–90° layer order is applied, at 15 wt% EBA-GMA content the unnotched impact strength increases by two and a half times and the notched impact strength by nine times compared to samples printed from elastomer-free RPET. DSC and DMA measurements proved that EBA-GMA reactively bonds to PET molecules, which is indicated by the increment of rigid amorphous phase and glass transition temperature and the reduction of crystallinity. The co-polymer molecules formed in-situ during compounding create a Toughening Enhancer Interphase (TEI), which also remains after 3D printing and effectively enhances impact strength. The strain at break and tensile strength of the filaments are substantially higher than that of 3D-printed specimens due to the increasing shrinkage and the resulting increased porosity of the printed specimens with higher EBA-GMA content. However, the Young-modulus values are quite similar. The flexural strength of the 3D-printed specimens reaches 40–60% of the values of injection moulded samples. The proposed method enables the production of parts with arbitrary geometry and balanced mechanical properties from RPET, which may substitute acrylonitrile butadiene styrene.

Recycled polyethylene terephthalate/ FeCo@C/ Silver nanowire/ polyimide sandwich membrane for electrothermal heating and electromagnetic interference shielding

The increasing frequency of global warming and extreme weather events raises concerns regarding energy conservation and efficient personal thermal management. As communication and technology progress, multifunctional wearable thermal management devices are gaining significant attention. In this study, a novel green recycled polyethylene terephthalate (rPET)-based sandwich composite with FeCo@C nanoparticles, silver nanowires (AgNWs), and polyimide tape (rPET/FeCo@C/AgNWs/PI) assembled by an efficient “filtering and taping” method was developed for multi-functions, including excellent Joule heat performance that rapidly increase to 165.7 ℃ at 0.9 V voltage in 12 s, electromagnetic interference shielding property with 49.35 dB at 120 μm thickness in the X-band (8.2–12.4 GHz), antibacterial and self-cleaning properties. Experimental results confirm the potential to the rPET/FeCo@C/AgNWs/PI composite for the thermal management and electromagnetic interference shielding.

AspenPlus-based techno-economic analysis of solar-assisted sorption-enhanced gasification for hydrogen and chemicals recovery from polyethylene terephthalate waste

Although the recycling of polyethylene terephthalate (PET) bottles is well-operating in several countries, less than 10% of PET plastic waste was recycled in a closed loop globally, and the rest was discarded as leakage. A process to recover hydrogen and valuable chemicals through solar-assisted PET sorption-enhanced gasification was analyzed. PET steam gasification with CaO and solar-assisted calcium looping processes were already experimentally studied in our previous work to obtain optimized processing conditions. In this paper, the integrated process with product purification, steam power plant, and LiBr-H2O absorption chiller was simulated with Aspen Plus based on previous experimental results to investigate the techno-economic performance. Material flows, energy balance, exergy destruction, and economics were analyzed. Day and night mode operations at different seasons were evaluated based on energy balance and the weather conditions of Naples, Italy. The energy and exergy efficiencies of day and night modes varied between 62%–72%. The annual production yields of hydrogen and benzene were 684 t and 6286 t, respectively. Due to the high production of benzene, its higher price (>1092 €/t) would make the project feasible with a larger than 12% internal rate of return value and competitive break-even hydrogen price (less than 4 €/kg). The results show that this integrated process could be technically and economically feasible. It has the potential to be implemented for hydrogen and benzene recovery from PET plastic waste with sustainable solar heat source and zero fossil CO2 emissions.

Environmental impact assessment via life cycle analysis on ultrafiltration membrane fabricated from polyethylene terephthalate waste to treat microalgal cultivation wastewater for reusability

The current study had conducted the life cycle analysis (LCA) to assess the environmental impact of microalgal wastewater treatment via an integrated membrane bioreactor. The functional unit selected for this analysis was 1 kg of treated microalgal wastewater with contaminants eliminated by ultrafiltration membrane fabricated from recycled polyethylene terephthalate waste. Meanwhile, the applied system boundary in this study was distinguished based on two scenarios, namely, cradle-to-gate encompassed wastewater treatment only and cradle-to-cradle which included the reutilization of treated wastewater to cultivate microalgae again. The environmental impacts and hotspots associated with the different stages of the wastewater treatment process had clearly elucidated that membrane treatment had ensued the highest impact, followed by microalgal harvesting, and finally cultivation. Among the environmental impact categories, water-related impact was found to be prominent in the following series: freshwater ecotoxicity, freshwater eutrophication and marine ecotoxicity. Notably, the key performance indicator of all environmental impact, i.e., the global warming potential was found to be very much lower at 2.94 × 10−4 kg CO2 eq as opposed to other literatures reported on the LCA of wastewater treatments using membranes. Overall, this study had proffered insights into the environmental impact of microalgal wastewater treatment and its stimulus for sustainable wastewater management. The findings of this study can be instrumental in making informed decision for optimizing microalgal wastewater treatment and reutilization assisted by membrane technology with an ultimate goal of enhancing sustainability.

Reversible Sensing Technologies Using Upcycled TPEE: Crafting pH and Light Responsive Materials towards Sustainable Monitoring.

Multiresponsive materials with reversible and durable characteristics are indispensable because of their promising applications in environmental change detections. To fabricate multiresponsive materials in mass production, however, complex reactions and impractical situations are often involved. Herein, a dual responsive (light and pH) spiropyran-based smart sensor fabricated by a simple layer-by-layer (LbL) assembly process from upcycled thermoplastic polyester elastomer (TPEE) materials derived from recycled polyethylene terephthalate (r-PET) is proposed. Positively charged chitosan solutions and negatively charged merocyanine-COOH (MC-COOH) solutions are employed in the LbL assembly technique, forming the chitosan-spiropyran deposited TPEE (TPEE-CH-SP) film. Upon UV irradiation, the spiropyran-COOH (SP-COOH)molecules on the TPEE-CH-SP film undergo the ring-opening isomerization, along with an apparent color change from colorless to purple, to transform into the MC-COOH molecules. By further exposing the TPEE-CH-MC film to hydrogen chloride (HCl) and nitric acid (HNO3) vapors, the MC-COOH molecules can be transformed into protonated merocyanine-COOH (MCH-COOH) with the simultaneous color change from purple to yellow.

PET mechanical recycling. A new principle for chain extender introduction

The introduction of chain extenders into the melt of recycled PET (rPET) is traditionally performed at the activation temperature of the extension reaction. The disadvantage of this approach is the low dispersion of chain extender particles, which does not contribute to the full extension reaction. As a result, some rPET chains do not react with the chain extenders, and unreacted chain extenders lead to a decrease in the crystallinity or crystallization rate of rPET, an increase in its degradation rate, and also present deleterious low molecular weight migrating compounds. Herein, a new principle of chain extenders introduction based on a two-stage scheme is considered for the first time, which includes a preliminary stage of mixing chain extenders in an rPET melt at a temperature below the activation temperature of the extension reaction and a stage of PET chain extension at the activation temperature of the extension reaction. It has been shown that rPET modified in this way has higher melt viscosity, strength and ductility compared to rPET modified in the traditional way. The reaction time is reduced by 10–20% depending on the type and concentration of chain extenders used. The differences in the structures formed are demonstrated by NMR, FTIR, DSC, WAXS and rheological test methods. The economic and environmental implications associated with the introduction of a new principle are discussed.

Mechanical recycling of PET containing mixtures of phosphorus flame retardants

Flame-retarded polymers, such as polyester textiles and sheets, are attracting attention with regard to their sustainability. Mechanical recycling is currently the most frequently used technique for improving the circularity of plastics. However, one complication of mechanical recycling is associated with the (still) inevitable mixtures of polymers and additives, which can influence material stability and significantly deteriorate the mechanical properties of recycled products. In this study, we aim to specifically investigate the interactions between mixtures of phosphorus flame retardants (FRs) in polyethylene terephthalate (PET) and evaluate their potential role in the mechanical recycling of melt-spun fibers. Two highly relevant commercial FRs, namely a DOPO-derivative (DOPO-PEPA or DP) and Aflammit PCO 900 (AF), are added to PET compounds as additives using a melt compounder. The melt stability of PET/FR compounds over extended processing time is assessed by chemical, thermal, and rheological measurements. DP shows a molecular lubrication effect, lowering the melt viscosity of PET, while AF promotes chemical changes (i.e., chain branching/crosslinking). Interestingly, a PET compound containing hybrid mixtures of DP/AF 20/80 (wt.%/wt.%) shows the most stable behavior at high temperatures under both nitrogen and air atmospheres, thus showing a synergistic effect. Most importantly, in a recycling scenario, the stabilization effect persists at diluted concentrations below the typical FR contents in PET. Multiple extrusion cycles are used to assess the repeated processing behavior of the compounds, and the mechanical properties and fire behavior of melt-spun fibers are compared before and after recycling. The results reveal that DP can maintain the mechanical performance of recycled PET/FR fibers, even if it is mixed (contaminated) with AF.

Safety assessment of the process CeltiPak, based on the Kreyenborg IR Clean+ technology, used to recycle post-consumer PET into food contact materials.

The EFSA Panel on Food Contact Materials, Enzymes and Processing Aids (CEP) assessed the safety of the recycling process CeltiPak (EU register number RECYC318), which uses the Kreyenborg IR Clean+ technology. The input material is hot caustic washed and dried poly(ethylene terephthalate) (PET) flakes originating from collected post-consumer PET containers, for example, bottles, with no more than 5% PET from non-food consumer applications. The flakes are heated in a continuous IR dryer (step 2) before being processed in a finisher reactor (step 3). Having examined the challenge test provided, the Panel concluded that step 2 and step 3 are critical in determining the decontamination efficiency of the process. The operating parameters to control the performance of these critical steps are temperature, air/PET ratio and residence time. It was demonstrated that this recycling process is able to ensure that the level of migration of potential unknown contaminants into food is below the conservatively modelled migration of 0.10 and 0.15 μg/kg food, derived from the exposure scenario for infants and toddlers, respectively, when such recycled PET is used at up to 100%. Therefore, the Panel concluded that the recycled PET obtained from this process is not considered to be of safety concern, when used at up to 100% for the manufacture of materials and articles for contact with all types of foodstuffs, including drinking water, for long-term storage at room temperature or below, with or without hotfill. Articles made of this recycled PET are not intended to be used in microwave and conventional ovens and such uses are not covered by this evaluation.

Safety assessment of the process Lietpak, based on the EREMA MPR technology, used to recycle post-consumer PET into food contact materials.

The EFSA Panel on Food Contact Materials, Enzymes and Processing Aids (CEP) assessed the safety of the recycling process Lietpak (EU register number RECYC319), which uses the EREMA MPR technology. The input material is hot caustic washed and dried poly(ethylene terephthalate) (PET) flakes originating from collected post-consumer PET containers, including no more than 5% PET from non-food consumer applications. The flakes are heated ■■■■■ under vacuum (step 2). Having examined the challenge test provided, the Panel concluded that this step 2, for which the challenge test was provided, is critical in determining the decontamination efficiency of the process. The operating parameters to control the performance of this step are temperature, pressure and residence time. It was demonstrated that this recycling process is able to ensure a level of migration of potential unknown contaminants into food below the conservatively modelled migration of 0.15 μg/kg food, derived from the exposure scenario for toddlers, when such recycled PET is used at up to 100%. Therefore, the Panel concluded that the recycled PET obtained from this process is not considered to be of safety concern when used at up to 100% for the manufacture of materials and articles for contact with all types of foodstuffs, except drinking water, for long-term storage at room temperature or below, with or without hot fill. Articles made of this recycled PET are not intended to be used in microwave or conventional ovens and such uses are not covered by this evaluation.

Influences of printing parameters on mechanical properties of recycled PET and PETG using fused granular fabrication technique

This research presents an investigation of the feasibility of recycled polyethylene terephthalate (rPET) and glycol-modified polyethylene terephthalate (rPETG) thermoplastics using the fused granular fabrication (FGF) 3D printing technique. It focuses on the effects of FGF printing parameters on the mechanical properties of rPET and rPETG printed parts using a Gigabot X 3D printer. The design of experiments (DOE) was first performed considering the main FGF 3D printing parameters such as layer thickness, infill density and number of contours. The experimental studies were then carried out to study the effects of printing parameters on the tensile properties based on the DOE. The effect of interlayer bonding of printed parts on the tensile properties was also evaluated using finite element-based multiscale modelling. Scanning electron microscopy (SEM) and Fourier transformation infrared (FTIR) spectroscopy were used to observe the fracture morphology and chemical structure of post-FGF printing products. The tensile test results indicate that the highest tensile strength of 26.4 MPa was obtained for rPET when using a 1.1-mm layer thickness, a 70% infill density, and 3 contours, whereas, for rPETG, the maximum tensile strength of 44.8 MPa was attained with a 1.2-mm layer thickness, a 100% infill density, and 2 contours. FTIR analysis confirms no significant changes of characteristic peaks for PET in the printed products, suggesting that rPET and rPETG are viable materials for FGF printing. Thermal stability studies also reveal that the glass transition temperature and onset degradation temperatures are not significantly affected by the printing parameters. The study demonstrates the potential of rPET and rPETG as sustainable alternatives to virgin materials and provides insights into the optimal processing conditions for achieving high-quality 3D printed parts via the FGF technique.

Nano-Scale and Macro-Scale Characterizations of the Effects of Recycled Plastics on Asphalt Binder Properties

This paper summarizes the results of one of the first comprehensive laboratory studies that was conducted to evaluate the effects of adding different contents of recycled polyethylene terephthalate (rPETE) as a modifier to an asphalt binder on the rheological and mechanical properties of the modified binder as well as on the agglomeration behavior between the rPETE and asphalt binder at a multiscale level. The high-temperature and low-temperature performances of the modified binder were investigated at the macro-scale and compared with those of the unmodified binder using dynamic shear rheometer (DSR) and bending-beam rheometer (BBR) rheological tests, as well as asphalt binder cracking device (ABCD) testing. The nano-scale evaluation of the binder properties, including the surface roughness, bonding energy, and reduced modulus, was accomplished using atomic force microscopy (AFM). The results indicated that the addition of rPETE enhanced the high- and intermediate-temperature rheological properties of the modified PG 64-22 binder. The low-temperature rheological properties and resistance to cracking decreased slightly with increasing rPETE content in the asphalt binder. However, this reduction was not remarkable when adding 4%, 8%, and 10% rPETE contents. The asphalt binder modified with 4% rPETE had a low-temperature grade of −22, similar to that of the unmodified binder, indicating that 4% rPETE can be added to the binder to improve its high- and intermediate-temperature properties without reducing its resistance to low-temperature damage. The AFM tapping-mode results indicated that the inclusion of rPETE in the asphalt binder improved the stiffness properties of the modified binder as compared with those of the control asphalt binder. In addition, the rPETE-modified binders showed rougher surfaces than the control binder. The addition of rPETE to the binder increased the values of the reduced modulus and bonding energy compared with those of the control binder.

Non‐isothermal crystallization kinetic of recycled PET and its blends with PBT modified with epoxy‐based multifunctional chain extender

AbstractA fundamental understanding of crystallization behavior is essential for the processing of both virgin and recycled polymers. This research delves into the crystallization characteristics and non‐isothermal crystallization kinetics of recycled polyethylene terephthalate (rPET) and its blends with poly butylene terephthalate (PBT), which have been modified using epoxy‐based multifunctional chain extenders (CE). The preparation of rPET/PBT blends involved a twin‐screw extruder, with varying weight ratios and different CE concentrations. Differential scanning calorimetry was employed to perform crystallization analysis on the samples. The results underscore the profound impact of blend composition on the thermal characteristics of the system, with CE exerting only a marginal influence. The glass transition temperatures (Tg) of the two polymers were measured at 49 and 79°C. During blending, the Tg values demonstrated variations relative to the proportions but did not adhere to the Fox equation. Furthermore, PBT was found to enhance the crystallization tendencies of rPET, resulting in an increase in relative crystallinity from 11% to 36%. Notably, the crystallization rate of PBT at 0.40 min−1 exceeded that of rPET at 0.36 min−1. PBT minimally affected the crystallization rate constant of rPET‐dominant blends, while rPET significantly reduced the crystallization rate in PBT‐dominant blends.

Structural behaviour of reinforced concrete beams containing recycled polyethylene terephthalate and sugarcane bagasse ash

Concrete is a widely used construction product. This product is presently concerned with the depleting nature of natural sand. Concrete is also being considered with supplementary materials to enhance its footprints. Hence, this study's goal is to examine the performance of reinforced concrete (RC) beams consisting of sustainable materials. The study seeks to qualify the use of concrete made using Sugarcane Bagasse Ash (SCBA) and Recycled Polyethylene Terephthalate (RPET) as structural elements. Proportionately, 10 % RPET is used to partially substitute sand, and 5 % SCBA is used to partially substitute cement. The innovation of this study is in the dual substitution approach and structural behaviour examination. The research probes how RPET and SCBA affect the RC beams’ flexural and shear capacities. The tests are completed ensuing 28 days of water curing. Three RC beams are made for each of the conventional concrete and SCBA-RPET concrete. A set of beams is made for the shear capacity test, while another set is made to examine flexural capacity. The beam dimensions are 160 × 200 × 1200mm3. The findings inform that the beams made with 5 % SCBA and 10 % RPET have a flexural capacity of 11 % less than the conventional beams'. However, the SCBA-RPET beams revealed a shear capacity that is 17.38 % more than the conventional beams'. The crack patterns during and after the shear and flexural strength tests are similar and comparable for the SCBA-RPET beams and the conventional beams. Thus, a sustainable concrete mix suitable for use as a structural beam is derived.

Optimization of 3D printer settings for recycled PET filament using analysis of variance (ANOVA)

Fused Deposition Modeling (FDM) 3D printing creates components by layering extruded material. Printer parameters such as layer height and infill density can greatly impact the mechanical properties and quality of the printed parts. One critical factor to be considered in analysis is the anisotropy nature of printed components, considering all cross-sectional area (CSA) profiles for less than 100% infill density. This paper investigates the effect of the anisotropy nature of 3D printed CSA has on stress calculations and hence mechanical properties of the specimen through Design of Experiment (DOE). Analysis of variance (ANOVA) is utilised to evaluate the results. Printed specimens were tensile tested as per ASTM D638-14. Raw data was analysed using various CSA profiles, taking changes in infill density and layer height into account. Fixed parameter such as shell count, top and bottom layers, nozzle diameter, Hexagonal pattern were defined. Specimens Ultimate Tensile Strength (UTS) values increased on average by 30% using average profile CSA data compared to using external specimen dimensions. Further analysis assessing printer parameters affect on recycled Polyethylene Terephthalate (rPET) specimen's Young's Modulus (YM) and UTS was studied. One significant finding from this study suggests that the thickness of each layer has the most significant impact on the material properties of 3D printed rPET, as observed through the analysis of tensile test data obtained from 3D printed samples. A 3D printed rPET specimen with 30% infill density and 0.25 mm layer height has a higher YM (1175 MPa) and UTS (39 MPa) compared to a specimen with 75% infill density and 0.1 mm layer height (1159 MPa, 31 MPa). However careful interpretation of the results is required because for the same 30% infill parameter at 0.2 mm layer height the YM (936 MPa) and UTM (28 MPa) are significantly lower than at 0.25 mm layer height. If a higher value of YM and UTS is required an infill setting of 50% and layer height of 0.25 mm gave the highest values, YM (1330 MPa) and UTS (43 MPa).

Sustainable Structural Lightweight Concrete with Recycled Polyethylene Terephthalate Waste Aggregate

Plastic is a widely consumed material with a high decomposition time, occupying significant space in landfills and dumps. Thus, strategies to reuse plastic waste are imperative for environmental benefit. Plastic waste is a promising eco-friendly building material for cement-based composites due to its reduced specific gravity and thermal conductivity. However, this waste reduces the composites’ mechanical strength. This work aims to produce and evaluate lightweight concretes made with only lightweight aggregates and mostly recycled plastic aggregates. Initially, an optimized dosage approach for lightweight concrete is presented. The mixture proportion of the lightweight concrete was based on the performance of mortars with the complete replacement of natural aggregate by recycled polyethylene terephthalate (PET) aggregates. The PET aggregates showed irregular shapes, impairing workability and providing lightweight concretes with around 18% water absorption and 21% void index. However, the concretes presented significantly low-unit weight, approximately 1200 kg/m3. This work presented a structural lightweight concrete (ACI 213-R) using only lightweight aggregates and mostly plastic waste aggregate, with a compressive strength of up to 17.6 MPa, a unit weight of 1282 kg/m3, and an efficiency factor of 12.3 MPa·cm3/g. The study shows that with an optimum dosage, reusing plastic waste in concrete is a viable alternative contributing to environmental sustainability.

Occurrence and prioritization of non-volatile substances in recycled PET flakes produced in China

Recycled PET (rPET) is gaining popularity for use in the production of new food contact materials (FCMs) under the context of circular economy. However, the limited information on contaminants in rPET from China and concerns about their potential risk are major obstacles to their use in FCM in China. Fifty-five non-volatile compounds were tentatively identified in 126 batches of hot-washed rPET flakes aimed for food packaging applications in China. Although the 55 substances are not necessarily migratable and may not end up in the contacting media, their presence indicates a need for proper management and control across the value chain. For this reason, the 55 substances prioritized on the basis of level of concerns and in-silico genotoxicity profiler. Among them, dimethoxyethyl phthalate, dibutyl phthalate, bis(2-ethylhexyl) phthalate were classified as level V substances, and Michler's ketone and 4-nitrophenol were both categorized as level V substances and had the genotoxic structure alert, while 2,4,5-trimethylaniline was specified with genotoxic structure alert. The above substances have high priority and may pose a potential risk to human health, therefore special attention should be paid to their migration from rPET. Aside from providing valuable information on non-volatile contaminants present in hot-washed rPET flakes coming from China, this article proposed a prioritization workflow that can be of great help to identify priority substances deserving special attention across the value chain.

High-toughness and antistatic PET/EMAG/CNTs nanocomposites from recycled sources by reactive compatibilization

The recycled polyethylene terephthalate (r-PET) based nanocomposites were prepared by incorporating pre-dispersed PEG-CNT hybrids and ethylene-methyl acrylate-glycidyl methacrylate elastomers (EMAG) through a two-step melt processing method. The epoxy groups of EMAG reacted with the carboxyl or hydroxyl groups of r-PET, thereby enhancing compatibility between r-PET and EMAG, exhibiting excellent toughening effects. Moreover, the presence of PEG coated CNT effectively prevented the agglomeration of CNT, then the volume repulsion effect of EMAG facilitated the formation of an efficient conductive network with a small amount of CNT (0.32 wt%). Consequently, r-PET/EMAG/PEG-CNT composites exhibited both excellent mechanical and conductive properties: the elongation at break was increased from 52% to 306%, the electrical conductivity increased from 10−13 S/cm to 10−8 S/cm and the percolation threshold was reduced by 56.9%. This work will provide a facile approach for designing high-toughness, antistatic r-PET/EMAG/PEG-CNT composites that have potential applications in automotive and electronic industries.