Recycled Polyethylene Terephthalate Research Articles

Effect of Recycled PET Particles as Aggregate on the Mechanical Strength of Concrete Pavement Blocks (CPBs)

Effect of Recycled PET Particles as Aggregate on the Mechanical Strength of Concrete Pavement Blocks (CPBs)

Preparation and characterization of ultrafiltration membranes derived from recycled Polyethylene terephthalate (PET) bottles

The pressing need for sustainable practices and eco-friendly materials in the face of escalating environmental concerns has led to exploring the transformation of discarded polyethylene terephthalate (PET) bottles into functional ultrafiltration membranes. This research prepares and characterizes ultrafiltration membranes derived from PET bottle waste. The study involves collecting PET waste material and fabrication processes to develop asymmetric flat sheet membranes blended with varying proportions of hydrophilic polyethylene glycol (PEG) using phase inversion techniques. Rigorous characterization employing SEM, EDS analysis, and water vapor permeability (WVP) assessments examine these membranes' structural, morphological, and performance attributes. The surface analysis elucidates a notable correlation between increased PEG content and larger pore sizes, consistent with prior studies involving PEG in membrane modifications. Additionally, incorporating PEG in the casting solution elevates water vapor permeability. Ultrafiltration experiments reveal differing rejection rates, with membrane M2 exhibiting enhanced anti-fouling properties despite reduced flux compared to M3 and M4. This research lays the groundwork for repurposing PET waste into selective membrane materials, emphasizing optimization strategies to enhance membrane quality and performance for diverse operational settings.

Thermal, thermomechanical and structural properties of recycled polyethylene terephthalate (rPET)/waste marble dust composites

The main objective of this work is to review the capability of using waste marble dust (MD) particles as reinforcing materials in recycled polymeric composites to achieve environmentally friendly materials. In the present study, polymer composites were fabricated from recycled polyethylene terephthalate (rPET) and MD and then analyzed for their structural and thermal properties. Preparation of rPET-based composites containing 0–20 wt% MD was carried out through extrusion and injection molding. For their characterization Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA) were applied. The DSC analysis revealed a nucleating effect of MD on rPET, which was manifested in a higher crystallization temperature (196.7 °C ⇒ 204.4 °C); however, the marble particles were also found to hamper chain mobility, thereby decreasing the crystallinity ratio (23.7 % ⇒ 19.2 %) of rPET and altering its crystalline structure. According to the TGA measurements, a slight increase occurred in the thermal stability of rPET, its major decomposition temperature increased from 446 °C to 451 °C when 20 wt% MD was incorporated into it. DMA showed an improved stiffness in the entire investigated temperature range for MD-filled composites versus neat rPET. Additionally, several factors were derived from the DMA data, including the effectiveness factor, degree of entanglement, and reinforcing efficiency factor which all suggested a decent interaction between the components indicating a proper reinforcing ability of marble powder. However, above 5 wt% MD content the reinforcing efficiency deteriorated due to the agglomeration of filler particles, which was also supported by scanning electron microscopic images.

Exploring the potential of Meldrum’s acid-bearing chain extenders for mechanical recycling of PET

Abstract Poly(ethylene terephthalate) (PET) is a widely used thermoplastic polymer with exceptional properties, making it a cornerstone in various industries. However, the extensive global demand for PET, particularly in the packaging sector, has led to significant ecological concerns due to inadequate recycling rates. This paper explores the potential of Meldrum’s acid-based chain extenders as a solution to enhance PET recycling. Initially, 2,2,5-trimethyl-5-(4-vinylbenzyl)-1,3-dioxane-4,6-dione (St-MA) was synthesized, and its homopolymers were produced through free radical polymerization and characterized through 1H NMR, FTIR and TGA analyses. Dynamic interactions between recycled PET (rPET) and the synthesized chain extender (HP) in an extrusion environment was further explored, resulting in higher T g and T c for rPET when 0.5 wt% of HP was added as a reactive chain extender. The chemical tunability of this functional ketene-based chain extender holds promise to enhance PET recycling practices. The continuous evolution of regulatory frameworks and environmental concerns may prompt the exploration of novel approaches, such as tailored Meldrum’s acid-bearing chain extenders, which might have the potential to reduce the ecological consequences associated with post-consumer PET waste.

Comparative analysis of environmental, social, and mechanical aspects of high-performance concrete with calcium oxide-activated slag reinforced with basalt, and recycled PET fibers

This paper studied the effects of steel, basalt, and recycled PET fibers on the environmental, social, and mechanical properties of high-performance concrete (HPC) with calcium oxide-activated slag (HPC-CAS). The energy consumption, greenhouse gas emissions, and human health impacts of concrete production were determined using resources, climate change, and human health indexes. The compressive strength, tensile and flexural strengths, modulus of elasticity, electrical resistance, and durability of HPC-CAS with different fiber types and contents were also measured and determined. Furthermore, the microstructure of HPC-CAS was examined by scanning electron microscope (SEM). The results revealed that 3 % recycled PET or basalt fibers increased the HPC-CAS tensile strength by 89 % and 55 %, respectively, and the flexural strength by 28 % % and 1.2 times, respectively, compared to specimens without fibers. The specimens with fibers also showed higher ductility and lower electrical resistance than those without fibers. The SEM analysis showed that basalt fibers had a better bond with the geopolymer matrix than recycled PET fibers. Basalt fibers had the lowest environmental impact and recycled PET fibers had the lowest social impact among the three types of fibers. However, recycled PET fibers also had lower mechanical performance and durability than basalt fibers. It was concluded, therefore, that the choice of fiber type for HPC-CAS depends on the balance between social, environmental, and technical criteria.

Enzymatic depolymerization of plastic materials by a highly efficient two-enzyme system

Advancing the efficiency of polyethylene terephthalate (PET) degradation is pivotal for sustainable and versatile PET recycling. In this study, we initially screened eight esterases, pinpointing Pyrobaculum calidifontis VA1 esterase (PCEST) as markedly effective in decomposing PET intermediate products. Building on this discovery, we engineered fusion proteins combining a robust cutinase (HRC) with PCEST, connected by flexible glycine-serine linkers. We further optimized the linker length, the sequential arrangement and the enzymatic conditions of the conjugated enzymes. Notably, the synergistic activity of the HRC-PCEST fusion protein significantly enhanced the breakdown of PET, thereby promising to streamline recycling processes. Collectively, this methodology not only propels the efficiency of PET degradation but also broadens the horizons for sustainable and versatile PET waste management protocols.

Superior glycidol-free chain extenders for post-consumer PET bottles and PET thermoform blends

The development of non-toxic, glycidol-free chain extenders is essential for enabling the recycling and reuse of both bottle-grade PET (PET-B) and thermoform PET (PET-T) in the packaging industry without the need for separation, thereby addressing the health concerns associated with commercial glycidol-based extenders. Herein, two novel series of novel glycidol-free chain extenders for bottle-grade recycled polyethylene terephthalate (PET-B) and thermoform-grade PET (PET-T) blends are reported. Blends of PET-B with up to 20 wt% of PET-T were incorporated into novel epoxy acrylate chain extenders with terminal (PEAT-BA) and internal (PEAI-BA) epoxy groups. These chain extenders are glycidol-free and improve the mechanical, rheological, and thermal properties of the PET-B/PET-T blends, offering better performance enhancements than are provided by commercial chain extender Joncryl ADR (J). The results showed significant improvements in intrinsic viscosity and mechanical properties by around 10 and 15 %, respectively, without affecting thermal properties. These findings can play a role in enabling the recycling and re-use of PET-B and PET-T blends without requiring separation while offering glycidol-free solutions.

Electrodialysis-Based Recovery of Water and Chemicals in Recycled Polyethylene Terephthalate Industries: Energy, Environmental, and Economic Performance

Electrodialysis-Based Recovery of Water and Chemicals in Recycled Polyethylene Terephthalate Industries: Energy, Environmental, and Economic Performance

Using recycled PET waste bottles clasp of ring strips in hollow concrete blocks in Iraq

Using recycled PET waste bottles clasp of ring strips in hollow concrete blocks in Iraq

Scale‐up fabrication and advanced properties of recycled polyethylene terephthalate aerogels from plastic waste

AbstractTraditional fabrication methods of aerogels are time consuming, toxic, and difficult to implement, making the production of aerogels expensive and severely limits widespread adoption. Nonwoven technology is introduced to prepare fibers that can be used to create polymer‐based aerogel. With its introduction, it allows the continuous flow of fine fibers and eliminates the bottlenecking fiber preparation phase of the fabrication process. Using recycled polyethylene terephthalate (rPET) fibers and polyvinyl alcohol, two types of rPET aerogels are successfully fabricated, namely the lab‐scale and the large‐scale aerogels, to investigate the effectiveness of the nonwoven process line for the fiber preparation processing step. Fibers prepared manually (lab‐scale aerogels) and with the aid of a fiber preparation production line (large‐scale aerogels) are characterized and compared. Both lab‐scale and large‐scale aerogels exhibited the required specifications of low densities (12.6–45.9 and 13.2–43.7 mg/cm3, respectively) and high porosity (99.1%–96.7% and 99.0%–96.8%, respectively). Their thermal conductivity (23.4–34.0 and 23.2–31.9 mW/m⋅K, respectively) and compressive modulus (4.74–21.91 and 4.53–22.29 kPa, respectively) were also relatively similar. The advantage of scaled preparation of fibers for aerogel manufacturing includes higher throughputs (the line can produce up to 60 kg/h), improved consistency for defibrillation, homogenous fiber blending, and accurate replication of laboratory‐made aerogel properties. This demonstrates the viability of using nonwoven technology to scale for continuous production to bring down the production cost.Highlights Scale up production of aerogels using nonwoven technology Improving preparation process of aerogels through homogenous fiber blending Preparation rate of up to 60 kg/h Developed high porosity aerogels up to 99% Good thermal insulation of 23.2–31.9 mW/m⋅K

Upcycling Fabrics: Valorization of Recycled Polyethylene Terephthalate (r-PET) Plastic Waste into Thermoplastic Polyester Elastomers (TPEE) for Fiber Spinning

Upcycling Fabrics: Valorization of Recycled Polyethylene Terephthalate (r-PET) Plastic Waste into Thermoplastic Polyester Elastomers (TPEE) for Fiber Spinning

Safety assessment of the process Reciclar, based on the EREMA Basic 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 Reciclar (EU register number RECYC314), which uses the EREMA Basic technology. The input material is ■■■■■ 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 in a continuous reactor under vacuum before being extruded. Having examined the challenge test provided, the Panel concluded that the continuous decontamination (step 2), for which a 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 0.1 μg/kg food, derived from the exposure scenario for infants, when such recycled PET is used at up to 95% in mixtures with virgin PET, and of 0.15 μg/kg food, derived from the exposure scenario for toddlers, when used at up to 100%. Therefore, the Panel concluded that the recycled PET obtained from this process is not of safety concern when used at up to 95% in mixtures with virgin PET for manufacturing of materials and articles for contact with all types of foodstuffs, including drinking water bottles, and 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 hotfill. 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.

Safety assessment of the process Novatex, based on the EREMA Basic 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 Novatex (EU register number RECYC313), which uses the EREMA Basic technology. The input material is ■■■■■ 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 in a continuous reactor under vacuum before being extruded. Having examined the challenge test provided, the Panel concluded that the continuous decontamination (step 2), for which a 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 0.1 μg/kg food derived from the exposure scenario for infants when such recycled PET is used at up to 95% in mixtures with virgin PET, and of 0.15 μg/kg food, derived from the exposure scenario for toddlers when used at up to 100%. Therefore, the Panel concluded that the recycled PET obtained from this process is not of safety concern when used at up to 95% in mixtures with virgin PET for manufacturing of materials and articles for contact with all types of foodstuffs, including drinking water bottles, and 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 hotfill. 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.

Production of antimicrobial nonwoven fabrics based on recycled polyethylene terephthalate (R-PET) fibers on industrial scale

One of the ultimate goals of this article is to produce antimicrobial polyester nonwoven fabrics on industrial scale. Therefore, the adaptation and development of pilot conditions for imparting polyester textile materials antimicrobial properties is highly needed. This will pave the way for establishment a technological package for the production of antimicrobial polyester nonwoven fabrics on industrial scale. The effect of semi-industrial scale treatment conditions, mainly antimicrobial substrate (AS) concentration, duration, and temperature on the (%) colony forming unit (CFU) reduction after treatment with aqueous solutions of AS was examined. The antimicrobial activity of treated with AS fibers against S. aureus, E. coli, and C. albicans was investigated using the shake flask method. All PET fibers bounded with AS showed outstanding antimicrobial activities against the previously mentioned three microorganisms. In fact the % of CFU reduction for all PET samples were significant, whereas it was null for the parent fibers.

Comparative life cycle assessment of a novel sustainable road pavement system adopting recycled plastic from PET bottles and carbonated aggregate

Road surfacing is crucial in improving community accessibility and mobility. Adopting sustainable measures is extremely important to prevent the significantly high environmental burdens associated with road pavement systems production. This study presents a comparative life cycle assessment of traditional pavement systems and their sustainable alternatives made and tested at the London South Bank University laboratories. The low-impact pavement mixes proposed herein provide a novel, innovative method for producing sustainable road systems. Unlike traditional approaches, these asphalt mixes utilise materials derived from recycled polyethylene terephthalate (plastics) and carbonated aggregates and are produced at temperatures significantly lower (warm mix).The Simapro software (Consultants, 2023) [1] was used to model the analysed asphalt mixes, and all life cycle inputs and outputs were characterised during the life cycle impact assessment phase into potential impacts using the IMPACT World + Midpoint method. Additionally, an uncertainty analysis employing Monte Carlo simulation was conducted to validate the life cycle assessment findings, reinforcing the robustness and credibility of this study's results. Notably, the assessment shows substantial reductions in the environmental impact of road pavement mixes adopting recycled plastic and carbonated aggregates, with various outcomes. Compared to traditional mixes, Climate Change emissions are reduced by approximately 40 %–60 %, Marine Eutrophication exhibits reductions of up to 30 %, and Freshwater Eutrophication decreases by up to 20 %. These findings suggest that integrating this sustainable road pavement approach can significantly reduce the environmental burdens of asphalt production and give asphalt a pivotal role in tackling waste reduction, carbon sequestration, and achieving Net Zero. Also, the proposed system can positively contribute to the current United Kingdom's (UK) circular policy model by reconsidering current waste management frameworks and integrating more efficient settings.

Denim industry wastewater treatment by a heterogeneous solar-Fenton process catalyzed by Fe supported on recycled polyethylene terephthalate (PET) by ultrasonic modification

The textile industry is an important economic sector; however, its wastewater generates a great impact on the environment. A heterogeneous solar Fenton (HSF) process was evaluated for denim wastewater treatment. The catalyst was obtained through ultrasonic modification of recycled polyethylene terephthalate (PET) with Fe nanoparticles (PET/NPs- Fe3O4). The SFH process was optimized using surface response methodology with a face-centered central composite design considering the effects of the hydraulic retention time (10, 25, and 40 min), hydrogen peroxide dosage (500, 1000, and 1500 mg/L), and mass of the packed catalyst (4, 6 and 8 g) on the color, COD, and turbidity removal efficiencies. The operating conditions for maximum COD removal were H2O2 541.7 mg/L, HRT 33.9 min, and PET/NPs- Fe3O4 dose 7.9 g with solar radiation. The removal of 91.2% COD, 86.2% color, 90.4% turbidity, and 81.9% TOC was obtained at 14.2 kJ/L QUva. PET modification yielded 1.6 mg Fe/g PET, and the modification method does not allow Fe leaching. The effluent obtained from the SFH process complies with the maximum permissible limits in Mexican legislation in terms of COD, TOC, turbidity, and color and allows the reuse of PET.

Using polyethylene terephthalate bottle waste as a viable precursor for the synthesis of unsaturated polyester resin in fabrication of jute fibre reinforced composites

The present research effort employs glycolysed polyethylene terephthalate (PET) bottle waste as a precursor for the synthesis of unsaturated polyester resin (rUPR). This resin is then used for manufacturing composites that are reinforced with jute fibres using the sheet moulding compound technique. The limited crosslinking of styrene in the rUPR was elucidated using a combination of differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) analysis. The elevated exothermic reaction energy of 1152 kJ and the clearly identifiable peak observed at 1620 cm−1 in the Fourier Transform Infrared (FTIR) spectrum provided substantial evidence for this phenomenon. Additionally, the X-ray diffraction (XRD) analysis indicated that the recycled unsaturated polyester resin (rUPR) demonstrated a higher level of amorphous nature This observation can be attributed to reduced viscosity and enhanced ductility of rUPR. The utilisation of the rUPR as a matrix material has shown significant effectiveness in enhancing the tensile and flexural properties of composites reinforced with jute fibres. Thereby, the objective of this research is to develop a thermoset resin using recycled polyethylene terephthalate (rUPR) waste material for identification its suitability in manufacturing composites with jute fibres as reinforcement.

Non-invasive optical property-based strategy to distinguish poly(ethylene terephthalate) containers of different recycled content

For Poly(ethylene terephthalate) (PET), one of the most widely used and re-used plastics, no definitive analytical method has been established to distinguish between the virgin form and its recycled counterpart. Numerous efforts have been made to achieve this purpose by mainly measuring thermal or mechanical properties and in this sense, the challenge arises from the fact that several factors can affect the characteristics of PET, recycled or not. In this study, the optical properties and their correlations for 28 PET containers with different mass, thickness and content of recycled material have been studied, normalized and parameterized to ultimately differentiate between both forms. Diffuse reflectance UV–Vis (DRS) spectra were unique for each sample and, while near-infrared (NIR) and Fourier-transform infrared-attenuated total reflectance (FT-IR-ATR) provided constant overall parameters regardless of the recycled %, fluorescence and Raman results indicated some differences between non-recycled and recycled PET. Furthermore, the Raman identification accuracy of the two groups was 96.4% and the fluorescence intensity could be related to the content of recycled PET. Moreover, water permeability tests were carried out on some samples, concluding that this property was correlated with the thickness of the plastic and not the recycled %. The study was completed by performing a multivariate analysis (PCA, box plot, K-means and hierarchical clustering analysis) to better understand the correlations within the variables studied and finally confirm the selection of those that allowed for a correct and sequential discrimination of the groups, resulting in a fast and non-invasive strategy that allows for an almost complete vPET-rPET distinction.

Coating mortars produced with recycled PET aggregates: A technical, environmental, and socioeconomic approach applied to Brazilian social housing

Plastic is one of the most used materials worldwide, and its final destination constitutes an environmental liability. Clean technologies aiming to reuse plastic waste are imperative from a socioeconomic and environmental perspective. In this sense, this work assesses a technical, thermal, and socioeconomic performance analysis of coating mortars produced entirely with recycled polyethylene terephthalate aggregates (PET), applied to a social housing prototype. The coating mortars’ bulk density was reduced by 30 %, and the compressive strength was impaired between 45 % and 65 % due to hydrophobicity, morphology, and specific gravity of PET aggregates. The PET-containing mortar that exhibited the most suitable properties for masonry coating was characterized in terms of thermal properties and adopted for building the energy simulation. In the sensitive analysis conducted for all bioclimatic zones in Brazil, the PET-containing mortar reduced the energy demand for home air conditioning by up to 12 %, which equals up to 92 % of the Brazilian minimum wage over one year. The socioeconomic analysis indicated that it is viable to use PET-containing mortars for masonry coating, with payback times between 2.4 months and 5.6 years, for one of the cities analyzed. The technical and economic feasibility of using PET-containing mortars for social housing internal and external masonry coating was also explored. This research highlights the benefits of reusing plastic waste in civil construction. This approach can contribute to developing other economic sectors, mitigate the housing deficit, and enhance the dignity of vulnerable populations worldwide.

Recycled PETg embedded with graphene, multi-walled carbon nanotubes and carbon black for high-performance conductive additive manufacturing feedstock.

The first report of conductive recycled polyethylene terephthalate glycol (rPETg) for additive manufacturing and electrochemical applications is reported herein. Graphene nanoplatelets (GNP), multi-walled carbon nanotubes (MWCNT) and carbon black (CB) were embedded within a recycled feedstock to produce a filament with lower resistance than commercially available conductive polylactic acid (PLA). In addition to electrical conductivity, the rPETg was able to hold >10 wt% more conductive filler without the use of a plasticiser, showed enhanced temperature stability, had a higher modulus, improved chemical resistance, lowered levels of solution ingress, and could be sterilised in ethanol. Using a mix of carbon materials CB/MWCNT/GNP (25/2.5/2.5 wt%) the electrochemical performance of the rPETg filament was significantly enhanced, providing a heterogenous electrochemical rate constant, k0, equating to 0.88 (±0.01) × 10-3 cm s-1 compared to 0.46 (±0.02) × 10-3 cm s-1 for commercial conductive PLA. This work presents a paradigm shift within the use of additive manufacturing and electrochemistry, allowing the production of electrodes with enhanced electrical, chemical and mechanical properties, whilst improving the sustainability of the production through the use of recycled feedstock.