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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Design principles for intrinsically circular polymers with tunable properties

This perspective discusses a set of design principles for next-generation kinetically trapped, intrinsically circular polymers (iCPs) that are inherently, selectively, and expediently depolymerizable to their monomer state once their kinetic barriers of deconstruction are overcome, thereby enabling not only the ideal shortest chemical circularity but also tunable performance properties. After describing four elements of the design principles - thermodynamics and kinetics, strategies to overcome trade-offs and unify conflicting properties, predictive modeling, and supply-chain life-cycle assessment and techno-economic analysis, which are illustrated with state-of-the-art examples - it concludes with presenting key challenges and opportunities for sustainable development of iCPs.

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

Rapid Polyolefin Plastic Hydrogenolysis Mediated by Single-Site Heterogeneous Electrophilic/Cationic Organo-group IV Catalysts

A homologous series of cationic electrophilic group IV metal hydrides (M = Ti, Zr, Hf) created by chemisorption of the corresponding MNp 4 precursors on highly Brønsted acidic sulfated alumina (AlS) to yield loosely coordinated surface AlS/MNp 2 (Np = neopentyl) species are systematically characterized by ICP, EXAFS/XANES, DRIFTS, and solid-state high-resolution multidimensional NMR spectroscopy (SSNMR), as well as by energy span DFT computation. With effective stirring, these complexes readily undergo reaction with H 2 to yield AlS/M(alkyl)H species, which are highly active for the hydrogenolysis of diverse commercial polyethylenes, α-olefin-ethylene copolymers, isotactic polypropylene, and postconsumer polyolefins including high-density polyethylenes, yielding medium and small linear and branched hydrocarbons at turnover frequencies as high as 36,300 h –1 at 200 °C/17 atm H 2 for M = Zr. For given polyolefin and reaction conditions, turnover frequencies scale approximately as M = Zr > Hf > Ti, whereas catalyst thermal stability scales approximately as M = Hf ≈ Zr > Ti, and these trends are qualitatively understandable from the DFT analysis. These catalytic results reveal that the AlS/Hf(R)H-mediated hydrogenolysis favors wax-like and liquid products, whereas the AlS/Zr(R)H-mediated hydrogenolysis can be tuned between gases and liquids. Finally, DFT analysis identifies β-alkyl elimination as the turnover-limiting C–C scission process, which is particularly facile in these cationic d 0 complexes but not so in the neutrally charged analogues.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

The lowdown on breakdown: Open questions in plant proteolysis

Abstract Proteolysis, including post-translational proteolytic processing as well as protein degradation and amino acid recycling, is an essential component of the growth and development of living organisms. In this article, experts in plant proteolysis pose and discuss compelling open questions in their areas of research. Topics covered include the role of proteolysis in the cell cycle, DNA damage response, mitochondrial function, the generation of N-terminal signals (degrons) that mark many proteins for degradation (N-terminal acetylation, the Arg/N-degron pathway, and the chloroplast N-degron pathway), developmental and metabolic signaling (photomorphogenesis, abscisic acid and strigolactone signaling, sugar metabolism, and postharvest regulation), plant responses to environmental signals (endoplasmic-reticulum-associated degradation, chloroplast-associated degradation, drought tolerance, and the growth-defense trade-off), and the functional diversification of peptidases. We hope these thought-provoking discussions help to stimulate further research.

Eckardt, Nancy A. (ORCID:0000000316581412)↗
NASA NTRS1980

Design, fabrication and testing of a dual catalyst ammonia removal system for a urine VCD unit

A three-man capacity catalytic system for the recovery of water from urine was designed, constructed, and tested, it was designed to operate with feed streams containing high concentrations of urine vapor and only 5 to 7% of oxygen for the oxidation of ammonia and volatile organic vapor.It can operate either in a flow-through or a recycle mode and is capable of accepting the urine vapor produced by a vapor compression distillation evaporator. Testing consisted of short preliminary and optimization test, an endurance test of 74 hours continuous operation, and recycle tests using both air and oxygen. The system was designed for a urine processing rate of 0.86 liters/hr; however, it was tested at rates up to 1.2 liter/hr. Untreated urine evaporated by an electrically heated evaporator was used. The quality of the recovered water meets the U.S. Drinking Water Standards, with the exception of a low pH. Accumulation of solids in the urine sludge is reduced to approximately 65% of the anticipated value.

Budinikas, P.↗
NASA NTRS1992

Annual report

The overall goal of the Tuskegee University Center for Food Production, Processing and Waste Management in Controlled Ecological Life Support Systems (CELSS) is to provide tested information and technologies applicable to bioregenerative food production systems for life support on long-term manned space mission. Specifically, the center is developing information, computer simulated models, methodologies and technology for sweetpotato and peanut biomass production and processing, inclusive of waste management and recycling of these crops selected by NASA for CELSS. The Center is organized into interdisciplinary teams of life scientists and engineers that work together on specific objectives and long-term goals. Integral to the goal of the Center is the development of both basic and applied research information and the training of young scientists and engineers, especially underrepresented minorities that will increase the professional pool in these disciplines and contribute to the advancement of space sciences and exploration.

Source record↗
DOE OSTI2022

Lithium metal recovery and synthesis

A process and system for creating a lithium ion anolyte from lithium alloys. Metal and lithium alloys are processed to remove the metal with lithium from the alloy remaining. A lithium ion anolyte formed may be used in a process to form lithium metal. Alternatively, a process and system for recovering lithium from sources such as lithium alloys and lithium metal oxides and other feedstock such as recycled batteries into a thin lithium metal film via electrodeposition in an organic electrolyte contacting both anode (holder for lithium source) and cathode (substrate for lithium deposition) in a single-compartment electrolysis cell.

Ignacio de Leon, Patricia Anne↗
DOE OSTI2022

Catalytic Chemical Recycling of Post-Consumer Polyethylene

Among commercial plastics, polyolefins are the most widely produced worldwide but have limited recyclability. Here, we report a chemical recycling route for the conversion of post-consumer high-density polyethylene (HDPE) into telechelic macromonomers suitable for circular reprocessing. Unsaturation was introduced into HDPE by catalytic dehydrogenation using an Ir-POCOP catalyst without an alkene acceptor. Cross-metathesis with 2-hydroxyethyl acrylate followed by hydrogenation transformed the partially unsaturated HDPE into telechelic macromonomers. The direct repolymerization of the macromonomers gave a brittle material due to the low overall weight-average molecular weight. Aminolysis of telechelic macromonomers with a small amount of diethanolamine increased the overall functionality. The resulting macromonomers were repolymerized through transesterification to generate a polymer with comparable mechanical properties to the starting post-consumer HDPE waste. Finally, depolymerization of the repolymerized material catalyzed by an organic base regenerated the telechelic macromonomers, thereby allowing waste polyethylene materials to enter a chemical recycling pathway.

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

Chemically Recyclable Polyester Thermosets from Activated Adipic Acid and Renewable Polyols

This study outlines a method for producing chemically recyclable crosslinked polyesters using renewable polyols-glycerol and sorbitol-combined with adipic acid (AA), which is transformed/activated into a polyanhydride mixture prior to use. A three-step procedure has been designed: 1) an acid-catalyzed reaction of AA with nontoxic isopropenyl acetate or acetic anhydride to form a crosslinking mixture (CLM) made of adipic-acetic mixed polyanhydrides; 2) a solvent- and additive-free process where glycerol or sorbitol, or a combination thereof, is reacted with the CLM to achieve a prepolymer, and 3) a casting/molding of the liquid viscous prepolymer to yield a thermoset as the end product. Different thermosets (eight examples) are prepared by changing the reagents ratio. These solids are thoroughly characterized by tensile tests, DMA, high-resolution magic angle spinning and solid-state NMR, thermal gravimetric analysis, DSC, and fourier transformed infra red (FT-IR) spectroscopy. The formation of cross-linked polyesters is confirmed in all cases, but mechanical properties varied significantly from one specimen to another. Interestingly, a tensile strength up to 18 MPa-approximately an order of magnitude higher than similar polymers-is achieved when sorbitol and the CLM are used in a 1:1 wt% ratio. The chemical recycle of the resulting polymers is achieved via methanolysis with quantitative recovery of the monomeric units.

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

A Polymer Degradation and Remanufacturing Experiment in the High School Classroom

Most students enter college without any exposure to polymer science, which leads to the poor understanding and slow implementation of plastic recycling programs in the United States. Here, to address the knowledge gap in chemical recycling, we introduce a 2-part laboratory experiment that was conducted in multiple high schools and public outreach events to demonstrate the depolymerization of PET via aminolysis and the remanufacturing of cleaved PET fragments into a new aramid polymer. Student experiences were evaluated with two postlab assignments.

Hands-on Learning↗
NASA NTRS2001

Benthic Marine Cyanobacterial Mat Ecosystems: Biogeochemistry and Biomarkers

Cyanobacterial mats are complete ecosystems that can include processes of primary production, diagenesis and lithification. Light sustains oxygenic photosynthesis, which in turn provides energy, organic matter and oxygen to the community. Due to both absorption and scattering phenomena, incident light is transformed with depth in the mat, both in intensity and spectral composition. Mobile photo synthesizers optimize their position with respect to this light gradient. When photosynthesis ceases at night, the upper layers of the mat become reduced and sulfidic. Counteracting gradients of oxygen and sulfide combine to provide daily-contrasting environments separated on a scale of a few mm. The functional complexity of mats, coupled with the highly proximal and ordered spatial arrangement of biota, offers the potential for a staggering number of interactions. At a minimum, the products of each functional group of microorganisms affect the other groups both positively and negatively. For example, cyanobacteria generate organic matter (potential substrates) but also oxygen (a toxin for many anaerobes). Anaerobic activity recycles nutrients to the photosynthesizers but also generates potentially toxic sulfide. The combination of benefits and hazards of light, oxygen and sulfide promotes the allocation of the various essential mat processes between light and dark periods, and to various depths in the mat. Observations of mats have produced numerous surprises. For example, obligately anaerobic processes can occur in the presence of abundant oxygen, highly reduced gases are produced in the presence of abundant sulfate, meiofauna thrive at high sulfide concentrations, and the mats' constituent populations respond to environmental changes in complex ways. While photosynthetic bacteria dominate the biomass and productivity of the mat, nonphotosynthetic, anaerobic processes constitute the ultimate biological filter on the ecosystem's emergent biosignatures, including those sedimentary textures, organic compounds, and minerals that enter the fossil record. The ability of cyanobacterial mats to channel abundant solar energy into the creation and maintenance of complex structures and processes has created a multitude of consequences, both for sedimentation and for the early evolution of our biosphere.

DesMarais, David J.↗
NASA NTRS1993

Incineration for resource recovery in a closed ecological life support system

A functional schematic, including mass and energy balance, of a solid waste processing system for a controlled ecological life support system (CELSS) was developed using Aspen Plus, a commercial computer simulation program. The primary processor in this system is an incinerator for oxidizing organic wastes. The major products derived from the incinerator are carbon dioxide and water, which can be recycled to a crop growth chamber (CGC) for food production. The majority of soluble inorganics are extracted or leached from the inedible biomass before they reach the incinerator, so that they can be returned directly to the CGC and reused as nutrients. The heat derived from combustion of organic compounds in the incinerator was used for phase-change water purification. The waste streams treated by the incinerator system conceptualized in this work are inedible biomass from a CGC, human urine (including urinal flush water) and feces, humidity condensate, shower water, and trash. It is estimated that the theoretical minimum surface area required for the radiator to reject the unusable heat output from this system would be 0.72 sq m/person at 298 K.

Upadhye, R. S.↗
DOE OSTI2023

Bona fide upcycling strategy of anhydride cured epoxy and reutilization of decomposed dual monomers into multipurpose applications

Waste epoxy materials become an enormous problem to society and the environment. The advantages of epoxy resins derive from their rigid and chemically stable networks, but these qualities also make them difficult to dispose of or recycle. In this work, we demonstrated an efficient degradation of anhydride cured epoxy resin by aminolysis in aminoethanol without using any catalysts. The epoxy resin was fully decomposed at 160 °C in 4 h, resulting in two distinct high purity monomers (HHPA-OH and BPA-OH). To fully realize this upcycling approach, The BPA-OH was used to synthesize a polyurethane coating with an excellent glass transition temperature (88.9 °C), scratch hardness (8H), gouge hardness (6H), adhesive strength (5B), and strong solvent resistance. The HHPA-OH with two hydroxyl groups was reacted with methacrylic anhydride to form a dimethacrylate monomer which was then used as a viable crosslinker for photo-curable 3D printing thermosetting polymer with tensile strength as high as 64 MPa and impact strength of 4.86 kJ/m 2 . This work demonstrates a feasible pathway to convert anhydride cured epoxy waste to new monomeric recyclates for superior polymer products.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Techno-economic and life cycle assessment of aluminum electrorefining from mixed scraps using ionic liquid

Aluminum production from bauxite ore uses significantly high amount of energy and capital expenditure. Recycle and reuse of aluminum can be economical and minimize the environmental impacts. Smelter based recycle and reuse of aluminum is used in recent days, however, it also uses high amount of energy with high cost of production and yields high life cycle impacts. The University of Alabama has developed aluminum electrorefining technology from mixed scraps using ionic liquids as an alternative to traditional smelter based recycle and reuse. This study has explored the techno-economical, and life cycle viability of that technology. An excel-based techno-economic and life cycle assessment model was developed at Idaho National Laboratory for techno-economic and life cycle assessment. SimaPro was used to get the necessary database for the life cycle assessment. This study determined that a 20,000 kg/day ionic liquid-based electrorefining system can be profitable with a net yearly profit of $2.00 million. Further, in terms of net global warming potential, it emits 0.92 kg CO 2 equivalent per kg of aluminum recycled, whereas the traditional smelter-based recycle technology emits 1.57 kg CO 2 equivalent per kg of aluminum recycled, and the aluminum production from bauxite ore emits 17.8 kg CO 2 equivalent per kg of aluminum produced. In other life cycle assessment categories, electrorefining of aluminum emits >88 % less than aluminum production from bauxite ore and it is also better than traditional aluminum recycling in six out of ten categories studied. This makes ionic liquid-based electrorefining technology a very promising technology in terms of process economics and environmental sustainability.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Chemically Recyclable and Tunable Polyolefin-Like Multiblock Copolymer Adhesives

Adhesives are important in creating multilayer products, such as in packaging and construction. Most current hot-melt adhesives such as poly(ethylene-co-vinyl acetate) (EVA) and polyurethanes lack chemical recyclability and do not easily de-bond, complicating recycling. Here, we achieved tunable adhesive properties of chemically recyclable polyolefin-like multiblock copolymers through regulating the incorporation of crystalline hard blocks, amorphous soft blocks, and ester content highlighted by adhesive strengths up to 6.80 MPa. We further demonstrated applications of these adhesives in multi-layer films and showed that the adhesives can be readily de-bonded, recovered, and chemically recycled. Overall, this study into structure-property relationships, including effects of crystallinity, soft-block incorporation, and ester content of the multiblock copolymers on adhesive properties, has resulted in a modular hot-melt adhesive platform that exhibits chemical recyclability for virgin-quality adhesive re-generation, reprocessability for repeated reuse of the recovered adhesive, and tunability for designing adhesives with a wide range of low to high (up to ~80% stronger than EVA) adhesion strengths.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Computational Approach for Rapidly Predicting Temperature–Dependent Polymer Solubilities Using Molecular–Scale Models

One promising approach to recycle multicomponent plastic waste (e. g., multilayer plastic films) is selective dissolution. Selective dissolution is a solvent-mediated process in which differences in polymer solubility in a carefully chosen solvent system are exploited to recover a target polymer. Here, a computational approach was developed that rapidly predicts temperature-dependent polymer solubilities to guide the design of solvent systems for solvent-mediated polymer recycling. Polymer conformations were obtained from molecular dynamics simulations by modeling the polymer as a short oligomer and then used as input to the conductor-like screening model for real solvents (COSMO-RS) for solubility predictions. Using polyethylene (PE) and ethylene vinyl alcohol (EVOH) as representative polymers, the effect of simulation parameters was systematically studied, and predicted solubilities were found to be in good agreement with experimental measurements. Furthermore, the applicability of the approach was demonstrated by identifying selective solvents for PE and EVOH dissolution from a library of 524 solvents.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Not Cutting Corners: Bioderived Triggers Driving Oxidative Main Chain Scission of Poly(ethylene terephthalate)

About 20–34 billion poly(ethylene terephthalate) (PET) bottles from the beverage industry leak into aquatic ecosystems annually, necessitating the development of urgent strategies to treat waterborne plastic pollution. Inspired by the scalability of water disinfection infrastructure and protocols, we present a dual depolymerization approach relying on oxidation, followed by hydrolysis. Incorporating bioderived monounsaturated C18 diacid (C18:1-DA) counits at low dosages (2–5%) in the PET backbone overcomes the diffusional limitations of depolymerizing PET in the solid state by suppressing the glass transition temperature of the copolymer by 20 °C. Cryomilled C18:1-PET powder suspended in an oxidant-loaded alkaline slurry underwent bulk depolymerization to oligomers at 80–100 °C via oxidative scissions at the internally located unsaturations. In contrast, conventional PET undergoes only minor end-chain scission under mild alkaline conditions. These oligomers are suitable for low-energy repolymerization or facile solvolysis to monomers. A permanganate-periodate oxidant couple demonstrated successful oxidation through the bulk of the polymer, which subsequently was hydrolyzed to monomers. Furthermore, this model system serves as a proxy for ozonolysis, followed by mild hydrolysis to reduce the energetics of alkaline hydrolysis. This integrated oxidation–hydrolysis strategy paves the way for the industrial adoption of cleaner, advanced oxidation processes, such as ozonolysis for plastic pretreatment, further enabling commercialized chemical recycling of unsaturation-containing polyesters.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗