Recycled PET Bottles Research Articles

Utilization of Alternative Fibres Manufactured from Recycled PET Bottles in Concrete Technology for the Improvement of Fire Resistance.

This article addresses the potential use of secondary polymer fibres in the field of structural concrete as a replacement for primary polymer fibres (mainly polypropylene/PP/), which are used in concrete to enhance its resistance when exposed to high temperatures (especially in the case of fire). Research has shown that, in addition to PP fibres, polyethylene terephthalate/PET/fibres, produced by recycling packaging materials (mainly PET bottles), can also be used as an alternative. These fibres are industrially produced in similar dimensions as PP fibres and exhibit similar behaviour when added to fresh and hardened concrete. In terms of their effect on increasing resistance to extreme heat loads, it has been found that despite a higher melting point (Tm), concrete with these fibres demonstrates comparable fire resistance. Therefore, it can be concluded that secondary PET fibres represent an interesting alternative to primary PP fibres from the perspective of a circular economy, and their use in construction represents a potentially valuable application for PET obtained through the collection and recycling of PET packaging materials.

Development of Multi-Walled Carbon Nanotube-Integrated Recycled Polyethylene Terephthalate Electrospun Antibacterial Face Mask

In this study, electrospun nanofiber membranes were successfully fabricated by modifying recycled polyethylene terephthalate (r-PET) with multi-walled carbon nanotubes (MWCNTs) for face mask applications. The recycling of PET bottles ensures effective waste management, while the electrospinning process facilitates the creation of delicate nano-range fibers. The inclusion of MWCNTs aimed to assess the antibacterial activity of the resulting nanomembranes. The fabricated samples underwent comprehensive characterization, including scanning electron microscopy (SEM), ultimate tensile testing, particulate filtration efficiency (PFE) testing, Fourier transform infrared spectroscopy (FTIR), and antibacterial sensitivity assays, revealing significant findings. MWCNTs incorporation led to minor bead formation in the membranes, with fiber diameters ranging from 446 to 862 nm. However, MWCNTs resulted in reduced stiffness and tensile properties due to the disruption of polymer chain alignment. The nanofiber membranes demonstrated effective filtration of 0.3 µm particulates, achieving filtration rates between 96 to 97%Functional group analysis confirmed the presence of both r-PET and MWCNTs in the composites. Although the r-PET/MWCNTs 12 kV membrane lacked an antibacterial zone of inhibition, it exhibited reductions of 28.64% for S. aureus and 31.9% for E. coli. These results collectively underscore the potential of r-PET/MWCNTs samples as an alternative nanofibrous membrane material for face masks. J. of Sci. and Tech. Res. 5(1): 63-74, 2023

Fish-Mimicking Hydrophilic and Hygroscopic Transparent Films with Long-Lasting Anti-Oil Adhesion and Its Application to PET Bottles

With the recent ban on the production and use of long-chain perfluorinated compounds, the development of alternative approaches to prepare liquid-repellent surfaces that avoids the use of such compounds has become an urgent issue. We have succeeded in the development of fish-mimicking hydrophilic transparent hydrogel-based films with long-lasting anti-oil adhesion properties. Such films could be prepared by simply mixing poly(vinylpyrrolidone) (PVP), nanoclay particles (NCPs), and a waterborne aminosilane (AOS) using an integral blend (IB) method. When submerged in water, these films displayed underwater superoleophobicity (advancing and receding contact angles (CAs) of diiodomethane were ~171°/~163°) with low CA hysteresis (less than 8°), because the hydrophilic nature of the films promoted the formation of a thin layer of adsorbed water on the topmost film surfaces, similar to fish scales. Furthermore, when our films were coated onto the inside of poly(ethylene terephthalate) (PET) bottles and pre-wetted using 80 °C hot water vapors, these film surfaces could effectively repel various oils and were able to maintain their oil-repellent properties for more than 5 weeks. These water-driven, non-perfluorinated transparent hydrogel-based films are expected to increase recycling of PET bottles for oils that are generally incinerated or landfilled.

Streamlining biological recycling of poly(ethylene terephthalate) via pre-treatment methods

In this study, we validated various methods of pre-treatment of poly(ethylene terephthalate) (PET) by the engineered yeast Yarrowia lipolytica. This research compares both the effect of the type of plastic used, the processing method and enzymes with different mechanisms of action (PETase and cutinase). The investigation demonstrated that the degradation efficiency varies depending on the type of plastic used, the processing methods and the applied enzyme. Moreover, it indicated that during prolonged yeast culture under the applied conditions, enzyme activity is not impaired. Among all the methods tested, the artificial aging process had the greatest impact on the degradation level by PETase, where the amount of TPA released from commercial PET film was the highest, and yielded over 2 gL-1. The maximum yield of TPA (0.59 gL-1), for the Y. lipolytica strain overexpressing cutinase, was observed during the process with recycled PET bottles shredded into 1 mm fragments. The maximum recorded weight loss of plastic film is over 70% for commercial PET film subjected to artificial ageing process.

Facilitating most population engagement with the circular economy: Challenges for academics and (as) social media influencers

The lack of consumer engagement with the Circular Economy (CE) hinders the use of recycled materials in products manufactured by the B2B companies (e.g., recycled pet bottles in industrial adhesives). Such an institutional void gives space to the rise of a type of network activity: knowledge brokerage, which is a process of knowledge exchange facilitation.This multiple case study contributes with a practical description of brokerage activities in this context. It investigated how companies could interact with academics through knowledge exchange translated into campaigns to engage most consumers with CE. The network approach, under the knowledge brokerage perspective, was the main theoretical foundation of this work.Findings indicate doubts that prevent companies from developing better green marketing campaigns. Academics could help to fill these gaps. Regarding campaign management, academics could identify the different groups of consumers, the delivery channels, campaign duration, and disclosure days/times that most engage each consumer group.Campaigns require educational materials. Academics could identify the amount of information and the presentation format in printed materials. However, engaging most of the population requires a better use of social media. Academics must investigate the posts that could change each group of people's behaviors (including consumers with a lower educational level and less purchasing power).Companies plan to financially support academics who elucidate these doubts or those who succeed in using social media to induce consumers to review their postures. Such support could increase the research funds for the projects managed by the researchers we have named “academic influencers.”

Characteristics of fibres based on secondary raw materials and their use in concrete technology

Different types of fibres in cementitious composites, particularly in concrete, are currently used for a number of reasons. Fibres are being added to improve mechanical properties (especially steel and glass fibres), to increase the durability – to reduce occurrence of microcracks during the concrete aging (mainly synthetic and cellulose fibres), or to increase the fire resistance (polypropylene fibres). Within the study, characterization of different types of alternative fibres (fibres generated during waste recycling that would otherwise end in incinerators or landfills) with possible use in cementitious composites. These were fibres from recycled PET bottles, paper, and mineral wool, whose properties were compared to the traditionally used cellulose and polypropylene fibres. In the experimental part, the thickness, length, shape, and surface of individual fibres were monitored by an optical microscope. Furthermore, the amount of heat of combustion was determined by the calorimetric method, and the differential thermal analysis (DTA) was carried out for determination of the impact of high temperature on monitored fibres. The microstructure of fibres was monitored using a scanning electron microscope. The focus of the experimental study was on fibres usable in concrete and capable of enduring high temperature stress.

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.

A Comparative Study Investigating the Feasibility and Potential of Utilising Polymer, Demolition & Glass Waste as a Partial Replacement for Fine and Coarse Aggregate in Concrete

The construction industry is a key CO2 contributor. Contemporary research focuses on formulating cement replacement composites; however, less attention is deliberated to formulating fine/coarse aggregate replacement composites. The waste from different fields contributes enormously to adverse environmental effects, thus necessitating reuse/recycling. The demolition/reconstruction of old buildings/infrastructure is adding further to the waste contribution by the construction industry. The total quantum of fine/coarse aggregate in the construction industry is estimated to be around 20 billion tons, contributing around a billion tons of CO2 . Therefore, even partial replacement of virgin sand/coarse aggregates with various waste materials like glass, rubber, plastic, tyres, recycled concrete and others will economise the cost of manufacturing the concrete with reduced CO2 footprints as eco-friendly materials. This study conducted a comparative analysis for investigation of the characteristic compressive and split tensile strength of concrete composites with partial replacement of virgin sand/coarse aggregate by 10-30% of Crushed Glass (CG), Crumb Rubber (CR), Recycled PET Bottles (RPB), Recycled Concrete Aggregate (RCA) and 5-10% of Shredded Tyres (ST). Generally, all the composites demonstrated par/ better strength with the control mix, achieving the target strength of C55/67 concrete. The composites with CG, RPB and RCA exhibited an improvement in compressive strength, attaining more than 70 MPa (high-performance concrete strength) and up to 10% improvement in split tensile, attaining 4.3 MPa. CR and 5-10% ST exhibited a slight decrease in compressive strengths. All the composites formulated in this study explicate their diverse uses for multipurpose infrastructural applications in the construction industry as improved, economical, eco-friendly waste absorbent composites.

Processing System for Plastic Bottle to Obtain Polyethylene Terephthalate Filament in 3D Printers

Plastic has become one of the most used materials in the world for many uses, especially PET plastic (polyethylene terephthalate) which is used to make plastic containers and bottles. In addition, in recent years there has been an increase in pollution due to its waste, which affects the terrestrial, marine, and climatic ecosystems. Since 2018, in Peru, thousands of tons of PET containers have been produced, of which only 21.9% was recycled. This generates great contamination of waste by plastic bottles that are produced annually. Therefore, it is important to carry out recycling processes to avoid contamination by PET bottles, which take more than 500 years to degrade. Therefore, new recycling processes are sought in areas of interest such as 3D printing technologies. For this reason, the objective of this paper is to implement a system that performs the recycling of PET bottles for use in 3D printing and thus contributes to reducing pollution. As a result, an electronic card was obtained for the automation of the foundry machine, cutting processes, casting, extrusion, and collection of filaments. In addition, a programming algorithm was developed to monitor and display the temperature based on a closed-loop system and thus obtain a higher performance and quality of PET filament.

Efficient glycolysis of used PET bottles into a high-quality valuable monomer using a shape-engineered MnOx nanocatalyst

The nanorod morphology of the MnOx material with the application of optimal calcination temperature exhibited good catalytic efficiency in the chemical recycling of PET bottles into a valuable monomer.

Sustainable plastic bottle recycling: employing zinc-deposited SBA-15 as a catalyst for glycolysis of polyethylene terephthalate

<abstract> <p>Novel catalysts for recycling PET bottles into monomers have been developed by depositing zinc onto the surface of SBA-15, mitigating ZnO catalyst agglomeration in glycolysis separation processes to enhance reaction yields. Various zinc compounds (Zn(OAc)<sub>2</sub>, ZnCl<sub>2</sub>, and ZnSO<sub>4</sub>) were employed as substrates for catalyst design on the porous, high-surface-area material SBA-15 <italic>via</italic> impregnation. The presence of distinct Zn species on SBA-15 was confirmed through XRD and EDS analyses. The acidity of the catalyst, a crucial factor in the PET glycolysis process, was assessed using different Zn-containing precursors. NH<sub>3</sub>-TPD measurement has revealed the highest acidity in ZnCl<sub>2</sub>, followed by Zn(OAc)<sub>2</sub> and ZnSO<sub>4</sub>, respectively. Glycolysis reactions with a PET:EG ratio of 1:5 and a 1% catalyst at 200℃ for 2 hours revealed the catalytic efficacy of zinc-deposited compounds in the sequence ZnCl<sub>2</sub> > Zn(OAc)<sub>2</sub> > ZnSO<sub>4</sub>. Surprisingly, the ZnCl<sub>2</sub> catalyst produced the highest yield of <italic>bis</italic>-2-hydroxyethyl terephthalate (BHET) at 75% and displayed exceptional recycling capability over three cycles, contributing significantly to resource recovery objectives aligned with the Sustainable Development Goals (SDGs).</p> </abstract>

Recycling PET Bottles for 3D-Printing Filament: Effect of Chain Extender

This study investigates the effect of a chain extender on the properties of recycled polyethylene terephthalate (rPET) for 3D printing filament. The research focuses on the melt flow index (MFI), mechanical properties, thermal behavior, and crystallinity of rPET blends with varying chain extender concentrations. MFI analysis reveals that the viscosity of rPET is influenced by the grade and sources of the PET bottles. The addition of the chain extender decreases MFI, indicating increased viscosity. Mechanical testing shows a slight decrease in impact strength with increasing chain extender concentration, suggesting the presence of limitations or constraints within the material. Thermal analysis demonstrates that the chain extender elevates the glass transition temperature (Tg) and melting temperature (Tm) of rPET, indicating enhanced rigidity and thermal resistance. However, the crystallinity (Xc) decreases as the chain extender disrupts the regular packing of polymer chains within the crystalline regions. These findings provide valuable insights into the influence of the chain extender on the properties of rPET for 3D printing filament. The research contributes to the development of sustainable manufacturing practices and promotes the utilization of recycled materials in additive manufacturing applications, furthering the goals of the circular economy and environmental sustainability.

Aqueous buffer solution-induced crystallization competes with enzymatic depolymerization of pre-treated post-consumer poly (ethylene terephthalate) waste

The complex relationship between kinetics and substrate morphology during enzymatic depolymerization of melt processed poly(ethylene terephthalate) (PET) is explored and the effects of competing transformations are analyzed. Extruded PET substrates from post-consumer recycled PET (RPET) bottles flakes subjected to enzymatic depolymerization are examined to reveal increases in crystallinity from ∼10% post-extrusion to > 30% after 3 days of depolymerization as well as increases in glass transition temperature (Tg) from ∼66 °C to > 80 °C. Further investigation into this behavior shows that post-extrusion RPET substrates do not exhibit changes in crystallinity when subjected to dry annealing at 65 °C in an oven over 7 days, but they do experience annealing in depolymerization buffer solution with no enzymes at 65 °C within 3 days. This difference may be attributed to plasticization of PET in the presence of water, also known as solvent induced crystallization. The impact of this plasticized annealing behavior is demonstrated by subjecting RPET substrates to increasing enzyme-to-substrate loads. As enzyme load increases, overall conversion of substrates increases despite crystallinity also increasing to similar levels regardless of the initial enzyme loading. The competition between depolymerization and crystallization suggests that the rate at which PET substrates are depolymerized at the operational temperature is integral to achieving high conversion to monomeric product. This, in turn, also suggests that savings from lowered enzyme loadings may be more detrimental than helpful in pursuing the most cost-effective recycling systems.

Anion Exchange Membranes Based on Chemical Modification of Recycled PET Bottles.

This study presents an innovative and effective solution for recycling PET bottles as raw for producing anion exchange membranes (AEMs) for electrochemical applications. This approach reduces the demand for pristine materials, a key principle of the circular economy and sustainability. PET was subjected to chemical modification by introducing cationic functional groups followed by methylation and OH- exchange process. The amination synthesis was optimized based on reaction time. The results indicate that ion exchange capacity, water uptake, and swelling ratio properties mainly depend on the degree of cationic functionalization. The optimized AEM exhibits ionic conductivity of 5.3 × 10-2 S·cm-1 and alkaline stability of 432 h in 1 M KOH at 80 °C. The membrane properties before and after the alkaline treatment were investigated using Fourier-transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy analysis. Computational chemistry analysis was employed to gain further insights into the membrane degradation mechanisms and pathways under alkaline conditions. This research and its findings are a step toward using recycled materials in the field of AEM technology.

Development of Recycled Air-filled PET Bottle Blocks for Cavity Wall Construction

This study examines the prospect of using PET bottles in mortar block for cavity wall construction in respect of compressive strength and cost. 500-mL air-filled waste plastic bottles encased by mortar plaster worked as the voids in the masonry units. Three different type of blocks B1, B2, B3 were prepared with the cement sand proportion 1:3, 1:3.5 and 1:4 respectively. Result shows that the strength decreased with the reduction of the proportion of cement. The maximum compressive strength found in B1which was 5.21 MPa after 7 days and 9.29 after 28 days of curing. B2 and B3 also shows 74% and 71% increase in strength as they reach the curing age of 28 days. The comparison of cost for wall construction with both bottle block and hollow concrete block shows, for external wall, the material cost can be reduced by 27% in the case of bottle block. So it can be used as a sustainable alternative of hollow concrete blocks in terms of strength and cost for cavity wall construction and have a great effect on plastic waste management. Key Words: Waste PET Bottles, Hollow Block, Compressive strength, Cost analysis.

REVERSE LOGISTICS: A CASE STUDY IN RELATION TO POST-CONSUMER RECYCLED PET BOTTLES (RPET) OF MINERAL WATER

Plastic packaging in general, due to its significant generation, has been configured as an environmental problem, especially when associated with inadequate disposal. In this context, the objective of the present work was to analyze the strategies and the reverse logistics process employed for the production of post-consumer recycled PET (rPET) bottles of mineral water from a factory located in the city of Poland, Maine, the United States (US) and point out reverse logistics actions between Brazil and the US. Data for mapping the reverse logistics process were obtained from secondary data, available electronically. The production cycle begins with the consumer through the correct disposal of the bottle, preferably in the vending machines, allowing the recycling company to recycle the residue and enable the manufacture of pellets. The company under consideration uses pellets to manufacture new rPET bottles, promoting a circular economy. Regarding reverse logistics strategies, the use of water bottle label was identified as a means of communication to inform the proper way of disposal, and the reimbursement given to consumers when disposing of their packaging in reverse vending machines.

Think before you throw! An analysis of behavioral interventions targeting PET bottle recycling in the United States

The United States generates 42 Mt of plastic waste each year and is one of the biggest contributors to ocean plastic waste. Consequently, plastic has become synonymous with the linear economy, and many scholars are studying and proposing circular economy solutions to mitigate plastic pollution. Recycling has received much attention from both social sciences and engineering as a circular economy strategy, but no study has yet quantified how behavioral interventions could asymmetrically affect different populations. This study combines agent-based modeling, material flow analysis, system dynamics, and life cycle assessment to assess the effect of four behavioral interventions on the collection rates of polyethylene terephthalate bottle waste, displaced virgin plastic manufacturing, and avoided greenhouse gas (GHG) emissions. Results show that, while behavioral interventions would require about 300–900 GJ of additional energy at end-of-life due to improved collection rates, they would avoid about 500–700 thousand metric tons of GHG emissions. Results also illustrate the importance of habits in disposal behaviors and show that different forms of interventions can be better adapted to particular social contexts than others. While the circular economy and its application to plastic waste should certainly not be restricted to recycling, this study demonstrates that improved collection rates and recycling technologies can contribute to reducing the amount of plastic waste polluting our oceans.

Open-loop recycling of post-consumer PET to closed-loop chemically recyclable high-performance polyimines

Intriguing high-performance polyimines (PI) were designed from diamines recovered by open-loop recycling of postconsumer PET bottles by microwave-assisted aminolysis. These new PIs had excellent thermal properties (Tm = 226–286 °C, Tg = 88–148 °C, heat resistance up to 327 °C) and super-high toughness and strength with Young's modulus of 4.02–4.93 GPa and tensile strength of 237–467 MPa, both significantly higher compared with common engineering plastics. The synthesized PIs also demonstrated recyclability “on demand” to original building blocks via mild and ultrafast acetic acid catalysed hydrolysis (70 °C for 10 min). Furthermore, the recovered monomer mixture was directly repolymerizable providing attractive closed-loop polymer-to-polymer recyclability under extremely mild conditions. These high performance thermoplastics, with easily tunable properties by selection of diamine used for aminolysis, in combination with closed-loop chemical recyclability have great promise as next-generation circular materials, designed from recycled plastics waste, for a wide property and application range.

3D Construction Printing Standing for Sustainability and Circularity: Material-Level Opportunities

Three-dimensional Cementitious materials Printing (3DCP) is a cutting-edge technology for the construction industry. Three-dimensional printed buildings have shown that a well-developed automated technology can foster valuable benefits, such as a freeform architectural design without formworks and reduced human intervention. However, scalability, commercialization and sustainability of the 3DPC technology remain critical issues. The current work presents the ecological fragility, challenges and opportunities inherent in decreasing the 3DCP environmental footprint at a material level (cementitious materials and aggregates). The very demanding performance of printable mixtures, namely in a fresh state, requires high dosages of cement and supplementary cementitious materials (SCM). Besides the heavy carbon footprint of cement production, the standard SCM availability might be an issue, especially in the longer term. One exciting option to decrease the embodied CO2 of 3DCP is, for example, to incorporate alternative and locally available SCM as partial cement replacements. Those alternative SCM can be wastes or by-products from industries or agriculture, with no added value. Moreover, the partial replacement of natural aggregate can also bring advantages for natural resource preservation. This work has highlighted the enormous potential of 3DCP to contribute to reducing the dependence on Portland cement and to manage the current colossal wastes and by-products with no added value, shifting to a Circular Economy. Though LCA analysis, mixture design revealed a critical parameter in the environmental impact of 3DCP elements or buildings. Even though cement significantly affects the LCA of 3DCP, it is crucial to achieving adequate fresh properties and rheology. From the literature survey, mixtures formulated with alternative SCM (wastes or by-products) are still restricted to rice husk ash, Municipal Solid Waste ashes and recycled powder from construction and demolition wastes. Natural aggregate replacement research has been focused on recycled fine sand, mine tailing, copper tailing, iron tailing, ornamental stone waste, recycled glass, crumb rubber, rubber powder and granules, recycled PET bottles and steel slag. However, flowability loss and mechanical strength decrease are still critical. Research efforts are needed to find low-carbon cement replacements and mix-design optimization, leading to a more sustainable and circular 3DCP while ensuring the final product performance.

Characterizing the changes to the material properties of a bottle‐grade poly(ethylene terephthalate) subject to repeated melt extrusion

AbstractAccording to 2018 data from the National Association of PET Container Resources, it is estimated that the recycling rate of the poly(ethylene terephthalate) (PET) bottle in the US is 29%. Trailing this figure is the amount of recycled PET bottles that are utilized for future applications, which is estimated at 20%. Over the previous decade, both values have remained relatively unchanged due to the dynamics of various factors. Ironically, one contributing factor is the mechanical recycling process itself, particularly if the material has been previously exposed. Repeated exposure to mechanical recycling can degrade the properties of the PET, limiting future utilization and in severe cases, destining the material for the landfill. Given the importance of the material properties to the proper functioning of the PET in a bottle application, it is imperative to understand how the properties of the material change when subject to repeated mechanical recycling. The aim for this research was to investigate how the properties of a virgin, bottle grade PET change when subject to a repeated step of the mechanical recycling process, melt extrusion. After each successive extrusion, changes in the thermal, rheological and mechanical properties were measured and compared to the virgin values.