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Results for “Polyethylene terephthalate (PET)”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

TCF Base Technology-Specific Final Report: Engineering Enzymes for Crystalline PET Substrate

The primary objective of this project was to develop a new polyethylene terephthalate (PET) hydrolase enzyme to depolymerize relevant PET substrates for Birch Biosciences, using high-throughput protein expression, purification, and assaying systems and machine learning-guided enzyme design. As a secondary project objective, we also aimed to develop a more energy-efficient ethylene glycol (EG) recovery strategy relative to distillation.

09 BIOMASS FUELS↗
DOE OSTI2020

Waste PET Chemical Processing to Terephthalic Amides and Their Effect on Asphalt Performance

The large amount of waste generated from polyethylene terephthalate (PET) packaging materials that have reached the end of life is creating a waste management issue that cannot be handled by mechanical recycling alone. Thus, it is imperative that alternate routes to recover and reuse these materials be pursued. A chemical recycling approach of mixed PET was demonstrated here that provides a mechanism by which PET waste can be efficiently recovered and repurposed to value-added products. The approach utilizes aminolysis of PET with a variety of amine nucleophiles, generating a small library of phthalimides with unique structures. In order to probe the high value of these products, the phthalimides were added to road-grade asphalt binder at 5 wt% and the resulting composite was evaluated. Specifically, rutting and fatigue characteristics as well as thermomechanical and creep performance were characterized and found to be improved by the inclusion of these additives by as much as 18%. In this work, additives made from deconstructed PET wastes were shown to improve the performance properties of asphalt at a variety of environmental conditions. These improvements would reduce the cost of road maintenance and provide a high-value market for waste PET. It is important to note that the asphalt binder utilized in this work was a commercial product already optimized for road conditions, not the raw bitumen; perhaps higher performance metrics could be obtained with virgin bitumen.

Recycling, Asphalt↗
DOE OSTI2023

Controlling PET oligomers vs monomers via microwave-induced heating and swelling

The production of polyethylene terephthalate (PET) bottles and fibers, and their subsequent mismanagement, have created an urgent need to develop strategies to handle the resulting waste. Here, in this work, glycolysis of PET using manganese oxide catalysts under microwave-assisted heating is demonstrated to form oligomers and the monomer bis(2-hydroxyethyl) terephthalate (BHET) at moderate conditions. Higher surface area catalysts achieve faster overall rates of depolymerization to the monomer. Oligomers form homogeneously and depolymerize to monomers over manganese oxide. The polymer-to-solvent ratio and reaction temperature affect the overall oligomer yield. The swelling of PET, caused by the diffusion of ethylene glycol into the polymer matrix, causes the dissolution of the PET to form oligomers. Oligomers are characterized and show similar physical properties to the starting PET despite having 1/20th of the molecular weight.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

BACKFLIP: Identification of Materials and Changes Upon Aging of Emerging Fluoropolymer-Free and Industry-Benchmark PV Backsheets

Extending lifetimes of photovoltaic (PV) modules and decreasing manufacturing and decommissioning costs are motivating research of novel PV module backsheet materials. Backsheet integrity is critical to the safety and performance of a PV module, however, the polymeric materials are often vulnerable to environmental degradation. The long-term durability of emerging polyolefin (PO) materials is being examined to inform regarding the possible replacement of laminated backsheets containing polyethylene terephthalate (PET) cores and fluoropolymer protective inner/outer layers. This study compares traditional PET-based backsheets with novel, co-extruded, and recyclable PO-based backsheets after being subjected to hygrometric and UV photolytic accelerated weathering. A large set of characterization methods will compare physical, chemical, structural, mechanical, and insulating properties of these backsheets and the resulting mini-module (MiMo) PV performances. The study of chemical composition, glass- and phase-transition temperatures, degree of crystallinity, and crystalline structure are described here.

mini-module↗
DOE OSTI2025

Conversion of Waste PET Plastic to Aramid Fiber

A three-step synthesis was used to convert waste polyethylene terephthalate (PET) into the high value polymer, poly-para-phenylene terephthalamide (PPTA), used in the production of high strength aramid fiber, such as Kevlar. Improvements to the polymerization reaction by addition of calcium chloride to the solvent, N-methyl-2-pyrrolidone (NMP), and rigorous anhydrous conditions enabled the production of a PET-derived PPTA with a 4.15 dL/g inherent viscosity in sulfuric acid that is amenable to fiber spinning. PPTA fibers were spun using a wet spinning apparatus under varied process parameters to assess their impact on fiber surface morphology, diameter, and the mechanical properties of the fibers. Select fibers were subjected to a post-spinning heat treatment at 150 °C , which improved the tensile strength and modulus by 100% and 30%, respectively, relative to the as-spun fibers. Techno-economic and life cycle analyses were conducted to evaluate the economic feasibility and the life-cycle greenhouse gases (GHG) emissions of the approach. In conclusion, the results suggest the potential for up to a 30% cost reduction, and comparable GHG emissions against conventional petroleum-based processes.

Lifecycle Analysis↗
DOE OSTI2024

Effects of transparent conducting electrodes and hole transport layers on the performance of MAPbI 3 solar cells fabricated on PET substrates

Abstract This study investigates how the performance of perovskite solar cells (PSCs) made on polyethylene terephthalate (PET) substrates depends on transparent conducting electrodes (TCEs) and hole transport layers (HTLs). We fabricated PSCs using commercially available PET/TCEs and compared their performance with PSCs manufactured on Glass/indium tin oxide (ITO) substrates. Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) with varying levels of acidity and NiO nanoparticles were used as HTLs. The current density-voltage characteristics of PSCs made on PET/TCEs were found to be significantly lower when highly acidic PEDOT:PSS was used as the HTL. However, this was not observed for PSCs made on Glass/ITO. To investigate the interaction between HTL and TCE, atomic force microscopy was carried out after dipping the TCEs in PEDOT:PSS solutions of different acidity. X-ray photoelectron spectroscopy measurements further revealed differences in the chemical composition between ITO film on PET vs. on glass. Our results indicate that the performance of PSCs depends both on the TCE substrates and HTLs, which can be explained by their chemical interaction.

14 SOLAR ENERGY↗
DOE OSTI2023

A Monte-Carlo Method for Evaluating the Economic Performance of Plastics Recycling Systems Using Historical Pricing

The management of plastic waste is a considerable emerging global concern. Conventional plastics recycling rates range from 5–10% in the US, which results in considerable material being sent to landfill. New sorting technologies using artificial intelligence have the potential to dramatically increase the ability of waste management companies to sort out valuable fractions of plastic waste and create high-purity streams for secondary markets. However, several fractions of the plastics recycling stream, i.e., low-density polyethylene, polypropylene, and polystyrene, do not have well-developed markets. These materials may be sent to pyrolysis facilities for thermal recycling, but the economics of the pyrolysis industry are currently uncertain. This work aims to identify the breakeven price of the plastic fractions that would be sent to pyrolysis in order to determine the economic viability of the sorting facility. The work will use Monte Carlo analysis to evaluate several scenarios and understand how compositional variation, price variability, and facility attributes affect the breakeven price. Here, the presorting conditions in Materials Recovery Facilities strongly affects the profitability of the sorting facility. High residual high density polyethylene (HDPE) and polyethylene terephthalate (PET) content in presorted bales are important revenue drivers for the facility, even in presorted 3-7 bales. Key variables that lead to profitability include a high sale price of polyethylene terephthalate, a high sale price of high-density polyethylene, and if polypropylene can be sold to recycling markets (as opposed to pyrolysis facilities).

Plastics↗
DOE OSTI2024

“Green” Fabrication of High-performance Transparent Conducting Electrodes by Blade Coating and Photonic Curing on PET for Perovskite Solar Cells

This study presents an innovative material processing approach to fabricate transparent conducting electrodes (TCEs) on polyethylene terephthalate (PET) substrates using blade coating and photonic curing. The hybrid TCEs consist of a multiscale Ag network, combining silver metal bus lines and nanowires, overcoated by an indium zinc oxide layer, and then photonically cured. Blade coating ensures film uniformity and thickness control over large areas. Photonic curing, a non-thermal processing method with significantly lower carbon emissions, enhances the conductivity and transparency of the coated layers. Our hybrid TCEs achieve an average transmittance of (81 ± 0.4)% referenced to air ((90 ± 0.4)% referenced to the PET substrate) in the visible range, an average sheet resistance of (11 ± 0.5) Ω sq−1, and an average surface roughness of (4.3 ± 0.4) nm. We benchmark these values against commercial PET/TCE substrates. Mechanical durability tests demonstrate <3% change in resistance after 2000 bending cycles at a 1 in radius. The scalable potential of the hybrid TCE fabrication method is demonstrated by high uniformity and excellent properties in 7 in × 8 in large-area samples and by performing the photonic curing process at 11 m min−1. Furthermore, halide perovskite solar cells fabricated on these hybrid TCEs achieve average and champion power conversion efficiencies of (10.5 ± 1.0) % and 12.2%, respectively, and significantly outperform devices made on commercial PET/TCEs. This work showcases our approach as a viable pathway for high-speed “green” manufacturing of high-performance TCEs on PET substrates for flexible optoelectronic devices.

Bonner, Justin C↗
DOE OSTI2023

Microwave-assisted depolymerization of PET over heterogeneous catalysts

The accumulation of plastic waste in the environment is rising and poses a significant environmental and health threat. Polyethylene terephthalate (PET), used mainly in single-use plastic bottles, accounts for a substantial fraction of this waste. The currently employed recycling strategies are inadequate to deal with the global plastic waste problem. PET glycolysis is a promising depolymerization method but has mainly been conducted using homogeneous catalysts; developing active and sustainable catalysts, and more energy-efficient processes remain challenges. Here, in this work, we implement microwave heating in PET glycolysis and identify ZnO as an excellent heterogeneous catalyst. We demonstrate the influence of ZnO's particle size and facet and hydrogen bonding on its activity. Finally, we demonstrate excellent performance for real-world post-consumer PET waste deconstruction with rapid depolymerization into bis(2-hydroxyethyl) terephthalate (BHET), achieving > 95% yields in less than 10 min. Cradle-to-gate life cycle assessment also indicates that BHET produced by ZnO-catalyzed glycolysis has lower global warming potential than the petrochemical-based production and homogeneously-catalyzed glycolysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Depolymerization of PET by common alkanolamines yields tunable monomers to expand the design space of 3D-printable, intrinsically self-healing polyamide-ionenes

Polyethylene terephthalate (PET), a ubiquitous thermoplastic used in textiles and packaging, is one of the primary contributors to plastic pollution. While PET is also one of the most recycled plastics, it has value as a rich source of chemical building blocks. When PET is depolymerized by amino alcohols (“alkanolamines”) such as monoethanolamine (MEA), terephthalamide-diol molecules are produced. In the presence of thionyl chloride (SOCl2), these diols are amenable to transformation to the corresponding dichloride monomers, which can then be polymerized via condensation methods (i.e., Menshutkin reaction) with bisimidazole compounds followed by ion-exchange to yield polyamide (PA)-ionenes with tailored structures. The PA-ionenes produced from these methods are intrinsically self-healing and possess thermal and mechanical properties which make them amenable to 3D printing. This study reports on synthetic methods and structure–property relationships in PA-ionenes that arise from the choice of molecular building blocks.

Bepari, Mousumi R. [Univ. of Alabama, Tuscaloosa, ↗
DOE OSTI2022

Catalytic co-pyrolysis of LDPE and PET with HZSM-5, H-beta, and HY: experiments and kinetic modelling

In this study, the catalytic pyrolysis of low-density polyethylene (LDPE), polyethylene terephthalate (PET) and their mixture (1 : 1 wt/wt) with three zeolite catalysts (HZSM-5, H-beta, HY) was investigated using a thermogravimetric analyzer (TGA) and a Pyroprobe® micro-reactor coupled to a gas chromatograph mass spectrometer (Py-GC/MS). The TGA results demonstrated that during pyrolysis at 10 °C min –1 , on average, zeolite catalysts decreased the maximum decomposition temperature by 149 °C for LDPE while only decreasing by 8 °C for PET. The derivative thermogravimetric (DTG) curve evidenced interactions when the two polymers were catalytically co-pyrolyzed for all the three catalysts. A lumped nth order reaction scheme was able to accurately model both non-catalytic and catalytic pyrolysis and co-pyrolysis by using the least squares fitting approach for determining the kinetic parameters. The kinetic model was able to model well the interaction effects observed during catalytic co-pyrolysis of LDPE and PET with HZSM-5, H-beta, and HY (Fit% Wt% > 96%, Fit% DTG > 94%). Py-GC/MS experiments for the catalytic fast pyrolysis of LDPE revealed that HZSM-5 resulted in the highest selectivity to aromatic hydrocarbons (31.6%) and HY resulted in the highest selectivity to gasoline range C 5 –C 10 paraffins and olefins (40.9%). Catalytic fast pyrolysis of PET showed high selectivity to benzene for all the catalysts (>43%) and that HZSM-5 resulted in the highest selectivity to polyaromatic hydrocarbons (24.7%). Finally, the catalytic fast co-pyrolysis of LDPE and PET revealed interaction effects for all the three catalysts evidenced by a positive synergy% for alkylated benzenes (3–142%) and polyaromatics (105–187%) with a concomitant negative synergy% for benzene (24–36%) and C 5 –C 10 paraffins and olefins (27–53%).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

A hybrid chemical-biological approach can upcycle mixed plastic waste with reduced cost and carbon footprint

Derived from renewable feedstocks, such as biomass, polylactic acid (PLA) is considered a more environmentally friendly plastic than conventional petroleum-based polyethylene terephthalate (PET). However, PLA must still be recycled, and its growing popularity and mixture with PET plastics at the disposal stage poses a cross-contamination threat in existing recycling facilities and results in low-value and low-quality recycled products. Hybrid upcycling has been proposed as a promising sustainable solution for mixed plastic waste, but its techno-economic and life cycle environmental performance remain understudied. We propose a hybrid upcycling approach using a biocompatible ionic liquid (IL) to first chemically depolymerize plastics and then convert the depolymerized stream via biological upgrading with no extra separation. Here we show that over 95% of mixed PET/PLA was depolymerized into the respective monomers, which then served as the sole carbon source for the growth of Pseudomonas putida, enabling the conversion of the depolymerized plastics into biodegradable polyhydroxyalkanoates (PHAs). In comparison to conventional commercial PHAs, the estimated optimal production cost and carbon footprint are reduced by 62% and 29%, respectively.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

United States plastics: Large flows, short lifetimes, and negligible recycling

Given increasing concerns for the marine environment and human health, as well as trade restrictions from Asian countries, plastics have become a great challenge for the United States. This study addresses the seven commonly used plastics: low-density polyethylene/linear low-density polyethylene, high-density polyethylene, polyethylene terephthalate (PET), polypropylene, polystyrene, polyvinyl chloride, and other plastics. Material flows of the seven polymers were tracked from production into fabrication, manufacturing, flow into use, waste management, and recycling in the United States in 2015. Low- and high-density polyethylene and polypropylene were found to be the largest in both production and product manufacture. More than 88% of the plastics went into three end-use sectors: Packaging, Consumer and Institutional Products, and Building and Construction. In-use lifetimes across the plastics are generally short. Virgin plastics were mainly exported, while intermediate plastic products were largely imported. The actual end-of-life recycling rate of the plastics as a group was no more than 6.2%, with PET and the polyethylene family the most recycled. Here, the high yearly plastic throughput and low recycling rate pose a serious challenge to the sustainability goals of the United States and is in stark contrast to the vision of a circular economy of plastics.

02 PETROLEUM↗
DOE OSTI2023

Insights into co-pyrolysis of polyethylene terephthalate and polyamide 6 mixture through experiments, kinetic modeling and machine learning

The non-isothermal pyrolysis of polyethylene terephthalate (PET), polyamide 6 (PA6), and their mixtures was studied in a thermogravimetric analyzer at different heating rates. Temperature of maximum decomposition (T max ) decreased by 25–45 °C and 35–55 °C for the PET:PA6 mixtures (3:1, 1:1, 1:3) compared to PET and PA6, respectively. The kinetic analysis was initially carried out using isoconversional method. However, the dependency of activation energy on conversion was observed for the co-pyrolysis of PET and PA6 that suggested the occurrence of multi-step reactions in the mixtures. Distributed activation energy model (DAEM) was used in this study to describe the multistep reactions occurring during pyrolysis of PET:PA6 mixtures. Here, in this work, a four-parallel reaction DAEM was developed to describe the pyrolysis kinetics of PET:PA6 mixtures. The apparent mean activation energies (E o ) for PET, PA6, and mixtures varied in the range of 244–255, 140–215, and 138–255 kJ mol –1 , respectively. The mass loss profiles of PET and PA6 mixtures were also modeled using artificial neural network (ANN). Out of 155 ANN models, the best prediction was made by ANN511 with R 2 greater than 0.997 for both test and unseen data. The interaction effects observed through TGA experiments and subsequent kinetic analysis were further assessed in terms of product composition using analytical pyrolysis coupled with gas chromatograph/mass spectrometer (Py-GC/MS). Co-pyrolysis of PET and PA6 resulted in the formation of new aromatic compounds with nitrogen-containing functional groups, which were not detected when PET or PA6 were pyrolyzed individually.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Systems Analysis and Optimization of Circular PET Packaging Supply Chains in the United States: Environmental and Socioeconomic Impacts

Many actions are underway at global, national, and local levels to address the plastic waste problem and transition toward a circular economy of plastics. Studies evaluating environmental and socioeconomic impacts of such a transition are lacking. Here, the purpose of this study is to conduct a national systems analysis of polyethylene terephthalate (PET) packaging supply chains in the United States. Material flow data was combined with environmental and socioeconomic indicators to evaluate and compare the sustainability of the linear PET packaging supply chain, current (2019) supply chain, and possible future circular supply chain options in the United States. Environmentally optimal circular US PET packaging material flows showed 31% and 38% savings of GHG emissions and energy demand, respectively, with a circularity of 77% when compared with a linear supply chain. Additionally, the environmentally optimal system showed higher employment (29%) and wages (31%) than a linear system, but with a 5% decrease in revenue generation. A socioeconomically optimal circular PET supply chain showed increased employment (by 52%), wages (by 67%), and revenues (by 1%), with a circularity of 59% when compared with the linear system. However, it showed 14% higher GHG emissions than a linear system, indicating a trade-off between environmentally and socioeconomically optimal circular PET packaging systems. Overall, linear-to-circular material flow transition may not necessarily lead to increased revenues and decreased environmental impacts of the entire system, but it does benefit society due to increased employment and wages. Future systems analysis work should focus on improving data quality for environmental and socioeconomic dimensions.

PET↗
DOE OSTI2022

Plastic glut down a microbial gut

Enzymes sequestered from microbes have demonstrated the ability to readily digest amorphous regions of polyethylene terephthalate (PET) in ambient conditions. Although nascent, enzymatic depolymerization can soon vie for commercialization and provide monomeric feedstock at rates comparable to petrochemical feedstock for repolymerization, achieving the coveted goal of cradle-to-cradle recycling. © 2022 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Intrinsic Kinetics of Polyethylene Terephthalate Pyrolysis via Micropyrolysis and Multivariate Chromatographic Analysis

This study provides an in-depth investigation of the primary decomposition of polyethylene terephthalate (PET) via pyrolysis, employing an experimental-analytic workflow that integrates design of experiments (DoE), micropyrolysis coupled with comprehensive two-dimensional gas chromatography (GC×GC), and multivariate data analysis to verify intrinsic kinetic conditions and elucidate evolving product distributions for mapping key reaction pathways. Peaks that could not be identified using commercial spectral libraries were assigned using Mass Frontier simulations, enabling the identification of divinyl terephthalate, ethyl vinyl terephthalate, and 2-(benzoyloxy)ethyl vinyl terephthalate. A polar×polar (non-orthogonal) column set tailored for the detection of carboxylic acids enhanced the quantification of benzoic acid, 4-vinylbenzoic acid, 4-ethylbenzoic acid, and methylbenzoic acid by up to 6-fold relative to an orthogonal column combination (non-polar×mid-polar). Moreover, pyrolysis variables were systematically evaluated using a Box- Behnken design (BBD), encompassing pyrolysis temperature (500−600 °C), sample weight (50−150 μg), and carrier gas flow rate (100−300 mL min −1 ). Among these, pyrolysis temperature was the only statistically significant factor influencing product yields, ranging from 58.78 to 84.26 wt %. In contrast, neither the sample weight nor the carrier gas flow rate had a significant effect on product yields within the evaluated experimental space. At 600 °C, the major pyrolysis products were benzoic acid (up to 20.20 ± 1.46 wt %) and CO 2 (up to 21.28 ± 1.46 wt %), which can be produced through decarboxylation reactions. These findings underscore the critical importance of selecting appropriate analytical columns for the accurate quantification of heteroatomcontaining products such as carboxylic acids, which may otherwise be underestimated or undetected due to their reactivity with the stationary phase of non-polar and mid-polar columns, as well as other GC components. They also highlight the importance of selecting pyrolysis conditions for investigating the primary decomposition of PET under an isothermal kinetically limited regime.

aromatic compounds↗
DOE OSTI2021

Cohesive and adhesive degradation in PET-based photovoltaic backsheets subjected to ultraviolet accelerated weathering

Delamination between layers in photovoltaic (PV) backsheets is often reported in the literature, causing voids that can collect moisture, diminish module backside heat dissipation, and reduce the backsheet’s effectiveness as a physical barrier. While backsheets with weathering-resistant fluoropolymer outer layers have traditionally been used in modules, more recent backsheets using non-fluoropolymer outer layers, such as polyethylene terephthalate (PET), have been developed. These backsheets have shown signs of premature degradation, and their adhesion degradation, in particular, has not been widely studied. In the present work, the single cantilever beam (SCB) adhesion test was used to quantify the adhesion energy in two commercially available PET-based backsheets. To study the effect of minor changes in formulation, the backsheets were obtained from same manufacturer and product line but during different years. To study the effect of environmental variables on adhesion degradation, the backsheets were subjected to artificial weathering at controlled temperature, humidity, and ultraviolet (UV) radiation in an indoor weathering chamber, and the adhesion energy was quantified at several intervals of exposure time. Layering structure, composition, and adhesion failure mode were compared between the backsheets, using Raman and infrared spectroscopy and thermogravimetric analysis. The results show a large difference in initial (unexposed) adhesion energy between the backsheets, despite very similar structures and compositions. Following exposure, adhesion energy dropped significantly, primarily due to thermo-hydrolytic degradation of the polyurethane (PU)-based adhesive layers. Significant UV-induced adhesion degradation of the PET outer layer surface was also observed. The study represents an important step in understanding adhesion degradation in PET-based backsheets, suggesting ways in which adhesion integrity – and, correspondingly, module service life – can be improved.

14 SOLAR ENERGY↗