Results for “Depolymerization” — Page 10

DOE OSTI2026

Highly Recyclable Thermosets for Lightweight Composites

The objective of this project, Highly Recyclable Thermosets for Lightweight Composites (DOE Award DE-EE0009297), was to develop recyclable carbon fiber–reinforced polymer (CFRP) composites that are more energy efficient to produce than existing technologies while achieving superior mechanical performance and enabling closed-loop material recovery. Specifically, the project targeted vitrimer-based composites with tensile strength at least 20% higher than baseline recyclable polypropylene composites, retention of greater than 95% of tensile strength after multiple recycling and reprocessing cycles, recovery of carbonate monomers through depolymerization, and recovery of greater than 95% of carbon fibers of reusable quality. The project was carried out by The University of Akron in collaboration with Pacific Northwest National Laboratory and Raytheon Technologies Research Center.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Hydrocracking Plastic Mixtures into Xylene

Our research aims to tackle the challenge in recycling end-of-life plastics, the accumulation of which has become a grand challenge to our society, sustainability and economy. Guided by life-cycle assessment (LCA) and tech-economic analysis (TEA), we specifically target the catalytic conversion of low-cost #3-7 plastic mixtures ($\$$5/ton) into p-xylene (>$\$$1000/ton), one of the most valuable hydrocarbon products. This goal is achieved by carrying out integrated research including catalysis, process engineering, and reactor design. The ultimate goal of this project is to enable energy-efficient and economically viable depolymerization of end-of-life plastic mixtures into value-added commodity chemicals.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2024

Infinitely Recyclable Network Polymers, Enabling Sustainable Manufacturing (CRADA Final Report)

This FLO Materials project was aimed at commercializing a new, infinitely recyclable material that can enable closed-loop lifecycles for hard-to-recycle plastics and plastic products. Four hundred million metric tons of virgin plastic is produced each year, yet less than 10% of this material is recycled. In the US alone, 2% of energy consumption is dedicated to the manufacture of virgin plastics, polymer resin, and synthetic rubbers. By keeping plastic materials in circulation longer, we can reduce waste, lower manufacturing costs, cut energy and oil consumption, and drastically reduce greenhouse gas (GHG) emissions. Specifically, FLO’s innovation overcomes the complications associated with salvaging difficult-to-recycle plastics (i.e., contaminated thermoplastic linear polymers, thermoset cross-linked network polymers), which represent at least 20% of total polymer global production, with a recycling rate of near 0%. Chemical recycling of these new polymers through depolymerization allows all additives to be easily removed at room temperature and the recovered monomers to be remanufactured into next generation materials with 100% recovery of mechanical performance and aesthetic quality.

36 MATERIALS SCIENCE↗

DOE OSTI2026

BOTTLE: Hybrid Chemical-Mechanical Separation and Upcycling of Mixed Plastic Waste

The main objective of this project is to develop a hybrid mechanical-chemical recycling technology for multilayered and laminated plastics. We aimed to separate and upcycle up to more than 80% of the two main constituents of such structures, polyolefins and polyesters, for a significantly lower cost and at higher energetic efficiency and much larger throughputs than chemical recycling. At the end of the project, the team was able to: a) Develop an extrusion-based separation technology that resorts to polyester depolymerizaton and extraction and allows for more than 90% of the polyester to be separated in the melt from the main polyolefin stream. b) Depolymerize the separated PET to more than 90%, which facilitates its posterior repolymerization and guarantees its retention in the polymer value-chain. c) Develop a zeolite-induced extrusion-based technology able to conduct continuous catalytic cracking of polyolefins, including highly contaminated PCR streams, at temperatures as low as 350 OC. d) Show, using LCA/TEA analysis that the two technologies are much more advantageous techno-economically and over the material’s life cycle than existing recycling technologies.

36 MATERIALS SCIENCE↗

DOE OSTI2026

Tabulated data for Lignin-Derived Phenolic Compounds and Water Are Effective Cosolvents for Reductive Catalytic Fractionation

Reductive catalytic fractionation (RCF) is an effective lignin-first biorefining method to extract lignin as a stabilized oil from lignocellulosic biomass. To realize RCF at scale, process modeling has shown that minimizing the use of exogenous organic solvents is critical. To this end, here we investigate the ability of lignin-derived monomers to act as either solvents or cosolvents for RCF. We begin by examining the influence of lignin-derived aromatic compounds (4-propylguaiacol, 4-propylphenol, and propylbenzene) on RCF monomer yields and subsequently extend our analysis to mixtures of 4-propylguaiacol and either methanol or water. We demonstrate that 4-propylguaiacol is an effective solvent for lignin extraction and depolymerization during RCF, especially when used in combination with water as a cosolvent. Cosolvent mixtures of 4-propylguaiacol and water enable up to 81% lignin extraction, monomer yields up to 25 wt %, and postreaction phase separation. However, unlike methanol, water as a cosolvent fails to inhibit aromatic ring hydrogenation when conducted over Ru/C as a catalyst, potentially leading to excess hydrogen consumption in a process utilizing this approach. Nonetheless, these results suggest a promising strategy for eliminating external organic solvents from RCF by utilizing mixtures of lignin-derived compounds and water as alternative extraction solvents. This is the tabulated data for the paper

biorefining↗

DOE OSTI2026

Calculation of monomer yields, verification of PG concentration approximation, catalyst comparison for neat aromatic RCF, SEM micrographs for postreaction pulps, yields of aqueous-phase sugar derivatives after PG-H2O RCF, reactor pressure transients, GPC comparing pre- and postreaction organic solvent composition, PG-H2O miscibility testing, GPC probing dimer/oligomer fractionation in PG-H2O mixtures for

Reductive catalytic fractionation (RCF) is an effective lignin-first biorefining method to extract lignin as a stabilized oil from lignocellulosic biomass. To realize RCF at scale, process modeling has shown that minimizing the use of exogenous organic solvents is critical. To this end, here we investigate the ability of lignin-derived monomers to act as either solvents or cosolvents for RCF. We begin by examining the influence of lignin-derived aromatic compounds (4-propylguaiacol, 4-propylphenol, and propylbenzene) on RCF monomer yields and subsequently extend our analysis to mixtures of 4-propylguaiacol and either methanol or water. We demonstrate that 4-propylguaiacol is an effective solvent for lignin extraction and depolymerization during RCF, especially when used in combination with water as a cosolvent. Cosolvent mixtures of 4-propylguaiacol and water enable up to 81% lignin extraction, monomer yields up to 25 wt %, and postreaction phase separation. However, unlike methanol, water as a cosolvent fails to inhibit aromatic ring hydrogenation when conducted over Ru/C as a catalyst, potentially leading to excess hydrogen consumption in a process utilizing this approach. Nonetheless, these results suggest a promising strategy for eliminating external organic solvents from RCF by utilizing mixtures of lignin-derived compounds and water as alternative extraction solvents.

biorefining↗

DOE OSTI2026

Lignin-Derived Phenolic Compounds and Water Are Effective Cosolvents for Reductive Catalytic Fractionation

Reductive catalytic fractionation (RCF) is an effective lignin-first biorefining method to extract lignin as a stabilized oil from lignocellulosic biomass. To realize RCF at scale, process modeling has shown that minimizing the use of exogenous organic solvents is critical. To this end, here we investigate the ability of lignin-derived monomers to act as either solvents or cosolvents for RCF. We begin by examining the influence of lignin-derived aromatic compounds (4-propylguaiacol, 4-propylphenol, and propylbenzene) on RCF monomer yields and subsequently extend our analysis to mixtures of 4-propylguaiacol and either methanol or water. We demonstrate that 4-propylguaiacol is an effective solvent for lignin extraction and depolymerization during RCF, especially when used in combination with water as a cosolvent. Cosolvent mixtures of 4-propylguaiacol and water enable up to 81% lignin extraction, monomer yields up to 25 wt %, and postreaction phase separation. However, unlike methanol, water as a cosolvent fails to inhibit aromatic ring hydrogenation when conducted over Ru/C as a catalyst, potentially leading to excess hydrogen consumption in a process utilizing this approach. Nonetheless, these results suggest a promising strategy for eliminating external organic solvents from RCF by utilizing mixtures of lignin-derived compounds and water as alternative extraction solvents.

biorefining↗

DOE OSTI2025

Hydrothermal Liquefaction of Structurally Diverse Lignins: Insights into Biocrude Yield, Fuel Properties, and Reaction Mechanisms

Lignin holds significant promise as a feedstock for biocrude production via hydrothermal liquefaction (HTL). Although lignin HTL has been widely studied, the specific depolymerization pathways associated with distinct lignin structures remain largely unexplored. This study investigates the HTL of four structurally diverse lignins: alkaline (AL), dealkaline (DAL), organosolv (OL), and lignosulfonate (LS) across 270–310 °C to elucidate structure-specific mechanisms governing biocrude yield and composition. AL and OL achieved the highest yields (16.8 ± 0.3% and 16.8 ± 2.5%), with AL-derived biocrude showing the highest carbon content (70.2 ± 0.0%) and HHV (31.0 ± 0.2 MJ/kg). In contrast, DAL and LS produced lower yields and inferior fuel quality due to higher sulfur content and lower carbon enrichment. The structures of AL and DAL, containing fewer methoxy groups, produced guaiacol-rich biocrudes (46.6% and 69.5%). Methylation in AL formed alkyl guaiacols and veratroles, while DAL favored side-chain oxidation. OL retained complex structures, forming syringols and desaspidinol, which contributed to heavier biocrude compounds. Sulfonate groups in LS were stabilized mostly as sulfides, leading to elevated sulfur content. These findings provide mechanistic insight into how lignin structure governs HTL behavior, enabling targeted control of biocrude yield and quality for renewable fuel production.

biocrude↗

DOE OSTI2024

Novel Charge-Ordered States in 1 T -IrTe 2

1T-IrTe 2 exhibits an intriguing series of charge-ordered states in both bulk and atomically thin layers. The charge orders in IrTe 2 emerge with consecutive first-order structural transitions involving in-plane Ir–Ir dimerization and interlayer Te–Te depolymerization, resulting in stripe patterns with various periods. Upon chemical doping, 1T-IrTe 2 can also be driven into a superconductor. Despite the intense research effort, a comprehensive understanding of the nature of the charge ordering and its relation to the superconductivity is yet to be reached. This review provides an overview of the novel charge orders and the emergence of superconductivity in IrTe 2 . Finally, we further introduce the recent studies on IrTe 2 nanoflake, in which novel charge orders attainable only in two-dimensional limits lay the grounds for an exotic phase diagram.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

NASA NTRS1970

Polymer degradation rate control of hybrid rocket combustion

Polymer degradation to small fragments is treated as a rate controlling step in hybrid rocket combustion. Both numerical and approximate analytical solutions of the complete energy and polymer chain bond conservation equations for the condensed phase are obtained. Comparison with inert atmosphere data is very good. It is found that the intersect of curves of pyrolysis rate versus interface temperature for hybrid combustors, with the thermal degradation theory, falls at a pyrolysis rate very close to that for which a pressure dependence begins to be observable. Since simple thermal degradation cannot give sufficient depolymerization at higher pyrolysis rates, it is suggested that oxidative catalysis of the process occurs at the surface, giving a first order dependence on reactive species concentration at the wall. Estimates of the ratio of this activation energy and interface temperature are in agreement with best fit procedures for hybrid combustion data. Requisite active species concentrations and flux are shown to be compatible with turbulent transport. Pressure dependence of hybrid rocket fuel regression rate is thus shown to be describable in a consistent manner in terms of reactive species catalysis of polymer degradation.

Stickler, D. B.↗

NASA NTRS1974

Effect of cavitation on fluid stability in polymer thickened fluids and lubricants

The effects of cavitating flow on the polymeric additives used in functional fluids are described. A comparison of thermal and mechanical stability tests for these polymer solutions show distinct differences in the machanism of the polymer degradation. The thermal degradation tests appear to cause an unzippering or depolymerization type of reaction in which there is no particular selectivity based on molecular weight. The mechanical degradation of these fluids appears to be based on molecular weight. Measurements of molecular weight distributions during mechanical degradation show that for a given level of intensity only molecules above a certain minimum size are degraded. The effects of ultrasonic radiation on polymer degradation are reported. Tests were conducted to demonstrate the mechanism of mechanical polymer degradiation in an orifice. A more severe test than the orifice test in which two tapered roller bearings loaded against each other produce the mechanical breakdown is discussed.

Duda, J. L.↗

NASA NTRS1977

Semiconductor grade, solar silicon purification project

The potential for a three step SiF2 polymer transport purification process was examined. The process involves reacting low cost mg silicon with SiF4 to yield SiF2 gas which is condensed to form polymeric (SiF2)x. The polymer is then heated above 400 C to yield Si, SiF4 and higher Si sub n F sub 2n+2 homologues. This report presents and discusses continuing progress on (1) observations on (SiF2)x polymer formation and depolymerization on the small coil, (2) mass balance studies, (3) partial pressures of SiF2 and SiF4, (4) AlF3 mass spectral studies, and (5) material analysis studies.

Ingle, W. M.↗

NASA NTRS1976

Formation of nucleoside 5'-polyphosphates under potentially prebiological conditions

The characteristics and efficiencies of biochemical reactions involving nucleoside 5'-diphosphates and -triphosphates (important substrates of RNA and DNA synthesis) under conditions corresponding to the primitive prebiotic earth are investigated. Urea catalysis of the formation of linear inorganic polyphosphates and metal ions promoting the reactions are discussed. Linear polyphosphate was incubated with Mg(++) in the presence of a nucleoside 5'-phosphate, to yield nucleoside 5'-polyphosphates when products are dried, while Mg(++) prompts depolymerization to trimetaphosphate in aqueous solutions. Plausible biogenetic pathways are examined.

Lohrmann, R.↗

NASA NTRS1980

The role of P2O5 in silicate melts

Phase equilibria data in the systems SiO2-P2O5, P2O5-M(x)O(y), and P2O5-M(x)O(y)-SiO2 are employed in conjunction with chromatographic and spectral data to investigate the role of P2O5 in silicate melts. P2O5 depolymerizes pure SiO2 melts by entering the network as a four-fold coordinated cation, but polymerizes melts in which an additional metal cation other than silicon is present. In this complex system P2O5 acts to increase phase separation by further enrichment of the high charge density cations Ti, Fe, Mg, Mn, Ca, in the ferrobasaltic liquid. The dual behavior of P2O5 is explained in a model which requires complexing of phosphate anions and metal cations in the melt. This interaction destroys Si-O-M-O-Si bonds polymerizing the melt. The higher concentration of Si-O-M-O-Si bond complexes in immiscible ferrobasaltic liquids relative to their conjugate immiscible granite liquids explains the partitioning of P2O5 into the ferrobasaltic liquid.

Ryerson, F. J.↗

NASA NTRS1980

Recovery of aluminum from composite propellants

Aluminum was recovered from solid rocket propellant containing a small amount of oxidizer by depolymerizing and dissolving propellant binders (containing functional or hydrolyzable groups in a solution of sodium methoxide) in an alcohol solvent optionally containing an aliphatic or aromatic hydrocarbon co-solvent. The solution was filtered to recover substantially all the aluminum in active form.

Shaw, G. C.↗

NASA NTRS1987

Effect of an oxygen plasma on the physical and chemical properties of several fluids for the Liquid Droplet Radiator

The Liquid Droplet Radiator is one of several radiator systems currently under investigation by NASA Lewis Research Center. It involves the direct exposure of the radiator working fluid to the space environment. An area of concern is the potential harmful effects of the low-Earth-orbit atomic oxygen environment on the radiator working fluid. To address this issue, seven candidate fluids were exposed to an oxygen plasma environment in a laboratory plasma asher. The fluids studied included Dow Corning 705 Diffusion Pump Fluid, polymethylphenylsiloxane and polydimethylsiloxane, both of which are experimental fluids made by Dow Corning, Fomblin Z25, made by Montedison, and three fluids from the Krytox family of fluids, Krytox 143AB, 1502, and 16256, which are made by DuPont. The fluids were characterized by noting changes in visual appearance, physical state, mass, and infrared spectra. Of the fluids tested, the Fomblin and the three Krytoxes were the least affected by the oxygen plasma. The only effect noted was a change in mass, which was most likely due to an oxygen-catalyzed depolymerization of the fluid molecule.

Gulino, Daniel A.↗

NASA NTRS1988

The basis for the spectral behaviour of silicates in the thermal infrared and applications to remote sensing

Variations in the thermal infrared (TIR) spectral response of silicate rocks is related to changes in the structures and divalent cation contents of the minerals which form the rocks. These considerations lead to a chemical parameter, SCFM, which reflects mineral structures, rock types, and their spectra. The parameter is the ratio of silica to the abundance of depolymerizing cations, defined as SCFM = SiO2/SiO2 + CaO + MgO + FeO. Parameter SCFM is therefore proposed for use in TIR remote sensing of igneous rocks. It is also demonstrated that two or three broad bands are sufficient for distinguishing among major rock types and the system noise has little effect on the quality of the results. These factors can be traded off against improved spatial resolution in instrument design.

Walter, L. S.↗

NASA NTRS1989

Spectral characterization of igneous rocks in the 8- to 12-micron region

This paper investigates the crystal-chemistry basis for the variation in spectral behavior of ingneous rocks, with the purpose of developing relationships useful for applications in the lithologic characterization of terrestrial and extraterrestrial surfaces. A new parameter is proposed for characterizing general rock and mineral type. The parameter, SCFM, defined as the ratio SiO2/(SiO2 + CaO + FeO + MgO), reflects the degree of depolymerization of the silica tetrahedra in both fine-grained and coarse-grained igneous rocks, and is a good descriptor of the composition of these rocks. Using spectra obtained in the laboratory on coarse-particulate mineral and solid-rock samples, the SCFM parameter was used to assess the effects of variations in the rock composition on the location, number, and width of spectral bands. A regression analysis of bands varying in width from 0.2 micron to 1.4 microns versus the SCFM value resulted in correlation coefficients ranging from 0.88 to 0.97.

Walter, Louis S.↗