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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Renewable unsaturated polyesters from muconic acid

cis,cis -Muconic acid is an unsaturated dicarboxylic acid that can be produced in high yields via biological conversion of sugars and lignin-derived aromatic compounds. Muconic acid is often targeted as an intermediate to direct replacement monomers such as adipic or terephthalic acid. However, the alkene groups in muconic acid provide incentive for its direct use in polymers, for example, in the synthesis of unsaturated polyester resins. Here, biologically derived muconic acid is incorporated into polyesters via condensation polymerization using the homologous series of poly(ethylene succinate), poly(propylene succinate), poly(butylene succinate), and poly(hexylene succinate). Additionally, dimethyl cis,cis -muconate is synthesized and subsequently incorporated into poly(butylene succinate). NMR measurements demonstrate that alkene bonds are present in the polymer backbones. In all cases, the glass transition temperatures are increased whereas the melting and degradation temperatures are decreased. In the case of poly(butylene succinate), utilization of neat muconic acid yields substoichiometric incorporation consistent with a tapered copolymer structure, whereas the muconate diester exhibits stoichiometric incorporation and a random copolymer structure based on thermal and mechanical properties. Prototypical fiberglass panels were produced by infusing a mixture of low molecular weight poly(butylene succinate-co-muconate) and styrene into a woven glass mat and thermally initiating polymerization resulting in thermoset composites with shear moduli in excess of 30 GPa, a value typical of commercial composites. The increased glass transition temperatures with increasing mucconic incorporation leads to improved composites properties. We find that the molecular tunability of poly(butylene succinate-co-muconate) as a tapered or random copolymer enables the tunability of composite properties. Altogether, this study demonstrates the utility of muconic acid as a monomer suitable for direct use in commercial composites.

09 BIOMASS FUELS↗
DOE OSTI2014

SU-E-T-115: Dose Perturbation Study of Self-Expandable Metal and Polyester Esophageal Stents in Proton Therapy Beams

Purpose: This work investigates dose perturbations due to Self-expandable metal and polyester esophageal stents undergoing proton radiotherapy for esophageal cancer. Methods: Five commercially available esophageal stents made of nitinol (Evolution, Wallflex and Ultraflex), stainless steel (Z-Stent) and polyester (Polyflex) were tested. Radiochromic film (GafChromic EBT3 film, Ashland, Covington, KY) wrapped around a stent and a 12cc syringe was irradiated with 2CGE (Cobalt Gray Equivalent) of proton beam in a custom fabricated acrylic phantom. An air-hollow syringe simulates the esophagus. Results: The Z-stent created the largest dose perturbations ranges from -14.5% to 6.1% due to the steel composition. The WallFlex, Evolution and Ultraflex stents produced the dose perturbation ranges of (−9.2%∼8.6%), (−6.8%∼5.7%) and (−6.2%∼6.2%), respectively. The PolyFlex stent contains the radiopaque tungsten markers located top, middle and bottom portions. When the focal cold spots induced by the markers were excluded in the analysis, the dose perturbation range was changed from (−11.6%∼6.4%) to (−0.6%∼5.0%). Conclusion: The magnitude of dose perturbation is related to material of a metallic stent. The non-metallic stent such as PolyFlex shows relatively lower dose perturbation than metallic stents except a radiopaque marker region. Overall Evolution and Ultraflex stent appear to be less dose perturbations. The largest dose perturbations (cold spots) were located at both edges of stents in distal area for the single proton beam irradiation study. The analysis of more than two proton beam which is more typical clinical beam arrangement would be necessary to minimize the doe perturbation effect in proton ratiotherapy.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2024

Closed‐Loop Recycling of Mixed Plastics of Polyester and CO 2 ‐Based Polycarbonate to a Single Monomer

Abstract Physical blending is an effective strategy for tailoring polymeric materials to specific application requirements. However, physically blended mixed plastics waste adds additional barriers in mechanical or chemical recycling. This difficulty arises from the intricate requirement for meticulous sorting and separation of the various polymers in the inherent incompatibility of mixed polymers during recycling. To overcome this impediment, this work furthers the emerging single‐monomer – multiple‐materials approach through the design of a bifunctional monomer that can not only orthogonally polymerize into two different types of polymers – specifically lactone‐based polyester and CO 2 ‐based polycarbonate – but the resultant polymers and their mixture can also be depolymerized back to the single, original monomer when facilitated by catalysis. Specifically, the lactone/epoxide hybrid bifunctional monomer (BiL O ) undergoes ring‐opening polymerization through the lactone manifold to produce polyester, PE(BiL O ), and is also applied to ring‐opening copolymerization with CO 2 , via the epoxide manifold, to yield polycarbonate, PC(BiL O ). Remarkably, a one‐pot recycling process of a BiL O ‐derived PE/PC blend back to the constituent monomer BiL O in >99 % selectivity was achieved with a superbase catalyst at 150 °C, thereby effectively obviating the requirement for sorting and separation typically required for recycling of mixed polymers.

Shi, Changxia↗
DOE OSTI2024

Closed‐Loop Recycling of Mixed Plastics of Polyester and CO 2 ‐Based Polycarbonate to a Single Monomer

Abstract Physical blending is an effective strategy for tailoring polymeric materials to specific application requirements. However, physically blended mixed plastics waste adds additional barriers in mechanical or chemical recycling. This difficulty arises from the intricate requirement for meticulous sorting and separation of the various polymers in the inherent incompatibility of mixed polymers during recycling. To overcome this impediment, this work furthers the emerging single‐monomer – multiple‐materials approach through the design of a bifunctional monomer that can not only orthogonally polymerize into two different types of polymers – specifically lactone‐based polyester and CO 2 ‐based polycarbonate – but the resultant polymers and their mixture can also be depolymerized back to the single, original monomer when facilitated by catalysis. Specifically, the lactone/epoxide hybrid bifunctional monomer (BiL O ) undergoes ring‐opening polymerization through the lactone manifold to produce polyester, PE(BiL O ), and is also applied to ring‐opening copolymerization with CO 2 , via the epoxide manifold, to yield polycarbonate, PC(BiL O ). Remarkably, a one‐pot recycling process of a BiL O ‐derived PE/PC blend back to the constituent monomer BiL O in >99 % selectivity was achieved with a superbase catalyst at 150 °C, thereby effectively obviating the requirement for sorting and separation typically required for recycling of mixed polymers.

Chemistry↗
DOE OSTI2022

Development of high‐performance partially biobased thermoset polyester using renewable building blocks from isosorbide, 1,3‐propanediol, and fumaric acid

Abstract Research on biobased thermoset resins has been overlooked when compared with the rapid progress on biobased thermoplastics. The objective of this work was to develop unsaturated polyester prepolymers based on building blocks derived from renewable raw materials, namely, biobased isosorbide, 1,3‐propanediol, and fumaric acid, with petroleum‐derived phthalic anhydride. The prepolymers developed herein behaved as low‐molecular weight macromolecules (oligoesters), with M n varying between 1.2 and 1.5 kDa, but achieved a high bio‐content of up to 87.1 wt%. The prepolymers were incorporated into reactive diluents comprising a blend of 2‐hydroxyethyl methacrylate and styrene, formulated to be eco‐friendlier and less toxic than typical styrene‐only incorporation approach, thus resulting in resins with viscosities between 750 and 950 cP. These resins are suitable for use in various fiber‐reinforced polymer production techniques, such as manual lamination, vacuum infusion, and pultrusion, having the benefit of presenting over 50 wt% of bio‐content in some formulations. Moreover, the crosslinked polyester resins (thermosets) exhibit comparable mechanical and thermomechanical behavior to their petrochemical‐based counterparts, with modulus of elasticity and tensile strength of up to 3.9 GPa and 62.1 MPa, respectively, and glass transition temperatures of up to 106°C, making them greener alternatives for high‐performance structural applications.

Hofmann, Mateus↗
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

Polyester-based epoxy vitrimer integrating spent coffee ground as a natural filler

Coffee is a widely consumed beverage, but approximately 80% mass of coffee cherry is discarded as waste. Here, in this study, spent coffee grounds (SCG) were recycled and used as a natural filler in a polyester-based epoxy matrix made from reactions of diglycidyl ethers of Bisphenol A and polyethylene glycol with methyl nadic anhydride. The properties of SCG/epoxy composites with various SCG contents up to 40% w/w were evaluated using various techniques such as FT-IR spectroscopy, tensile testing, optical microscopy, differential scanning calorimetry, and rheology. The SCG filled polyester-based epoxy matrix demonstrated excellent dimensional stability and retained a permanently crosslinked network, but re-shaping was possible at ~150 °C through transesterification, which occurred due to a dynamic chain exchange reaction between the ester group of the epoxy matrix and the hydroxyl group of the SCG fillers. The transesterification also improved the interfacial adhesion between the matrix and SCG fillers, resulting in tensile strength of over 20 MPa and a modulus of around 2.5 GPa, even with high SCG contents up to 40% w/w. While neat, cured epoxy shows thermoset behavior, filling the matrix with SCG enables reforming and origami-inspired spontaneous change in shape.

42 ENGINEERING↗
DOE OSTI2023

Synthesis, characterization, and recycling of bio-derivable polyester covalently adaptable networks for industrial composite applications

Fiber-reinforced polymers (FRPs) are critical for energy-relevant applications such as wind turbine blades. Despite this, the end-of-life options for FRPs are limited as they are permanently cross-linked thermosets. To enable the circularity of FRPs, we formulated a bio-derivable polyester covalently adaptable network (PECAN), sometimes referred to as a polyester vitrimer, to manufacture FRPs at >1 kg scale, which is accomplished as the resin is infusible (175-425 cP at 25 °C viscosity), can be cured at 80 °C within 5 h and is depolymerizable via methanolysis yielding high-quality fibers and recoverable hardener. The FRPs exhibit a transverse tensile modulus comparable with today's wind relevant FRPs (10.4-11.9 GPa). Modeling estimates a resin minimum selling price of $2.28/kg and, relative to an epoxy-amine resin, PECAN manufacture requires 19%-21% less supply chain energy and emits 33%-35% less greenhouse gas emissions. Overall, this study suggests that redesigned thermosets can yield beneficial circularity.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Unraveling substituent effects on the glass transition temperatures of biorenewable polyesters

Converting biomass-based feedstocks into polymers not only reduces our reliance on fossil fuels, but also furnishes multiple opportunities to design biorenewable polymers with targeted properties and functionalities. Here we report a series of high glass transition temperature (T g up to 184°C) polyesters derived from sugar-based furan derivatives as well as a joint experimental and theoretical study of substituent effects on their thermal properties. Surprisingly, we find that polymers with moderate steric hindrance exhibit the highest T g values. Through a detailed Ramachandran-type analysis of the rotational flexibility of the polymer backbone, we find that additional steric hindrance does not necessarily increase chain stiffness in these polyesters. We attribute this interesting structure-property relationship to a complex interplay between methyl-induced steric strain and the concerted rotations along the polymer backbone. We believe that our findings provide key insight into the relationship between structure and thermal properties across a range of synthetic polymers.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Mechanically robust and reprocessable imine exchange networks from modular polyester pre-polymers

Covalent adaptable networks (CANs) containing reversible cross-links impart recyclability to thermoset materials without sacrificing their desirable properties (e.g. high tensile strength and solvent resistance). In addition to thermal recycling, the sustainability of these materials may be further improved by incorporating bio-sourced monomers or by enabling alternate end-of-life fates, such as biodegradation or recovery of starting materials. The alternating ring-opening copolymerisation of epoxides and cyclic anhydrides permits the modular synthesis of polyester pre-polymers that can then be cross-linked to form dynamic imine-linked networks. In this work, we report the synthesis and characterisation of five imine exchange polyester CANs with varied cross-linking densities and pre-polymer architectures. While the materials exhibit characteristic thermoset properties at service temperatures, differences in pre-polymer architecture produce distinct dynamic mechanical effects at elevated temperatures. The networks may be thermally reprocessed with full recovery of their tensile strengths and cross-linking densities, dissociated to pre-polymer, or hydrolytically degraded.

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

High performance long chain polyesters via melt copolymerization of cutin-inspired monomers

Biopolymers have exhibited potential as sustainable and circular replacements to existing commodity thermoplastic polymers. However, current biopolymers are limited by poor thermomechanical performance compared with their petroleum-derived counterparts. Herein, we report a simple strategy to achieve good mechanical properties in bio-inspired long-chain polyesters via melt copolymerization. By combining mono- and poly-hydroxyl functionalized long chain fatty acids, we show that tough, semi-crystalline materials can be produced that outperform related biopolymers in terms of their thermomechanical behavior. Finally, we envision that long-chain polyesters derived from hydroxylated fatty acids represent an ideal platform to create the next generation of commodity thermoplastics that possess advantaged properties, inherent biodegradability, and feedstock stability.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Vinylester and Polyester 3D Printing

ORNL collaborated with Polynt Composites USA to evaluate the feasibility of vinylester and polyester 3D printing. Multiple materials were tested and evaluated. The evaluation consisted of rheology measurements, print trials and mechanical testing. Significant effort was devoted to safe handling of large quantities of these materials. The feasibility of using vinylester and polyester materials for large scale 3D printing has been demonstrated with outstanding issues identified in this report.

36 MATERIALS SCIENCE↗
NASA NTRS1972

Comparison of polyester, film-yarn composite, balloon materials subjected to shear and biaxial loading

A series of candidate materials for use in large balloons was tested and their tensile and shear strength capabilities were compared. The tests were done in a cold box at -68 C (-90 F). Some of these materials were fabricated on a special machine called the flying thread loom. This machine laminates various patterns of polyester yarn to a thin polyester film. The results show that the shear strength of materials changes with the angle selected for the transverse yarns, and substantial increases in biaxial load carrying capabilities, compared to materials formerly used, are possible. The loom capabilities and the test methods are discussed.

Niccum, R. J.↗
DOE OSTI2023

Synthesis of functional polyurethanes and polyesters from biomass-derived monomers

A method of making polyesters and polyurethanes from biomass-derived polyols. The polyol is biomass-derived and has the structure: wherein dashed bonds are single or double bonds and R is selected from the group consisting of —OH and ═O. Polyurethanes are made by reacting the polyol with a diisocyanate. Polyesters are made by reacting the polyol with a dicarboxylic acid.

Chang, Hochan↗
DOE OSTI2024

Enzymatic depolymerization of polyester: Foaming as a pretreatment to increase specific surface area

Abstract Poly(ethylene terephthalate) (PET) is widely used for its high strength‐to‐weight ratio, gas barrier properties, and chemical resistance. The growing PET use highlights the demand for a better recycling system. Enzymatic recycling, alongside mechanical and chemical methods, is eco‐friendly and yields properties similar to virgin PET. Substrate properties ( T g , crystallinity, and specific surface area [SSA]) and enzyme stability significantly impact conversion efficiency. Higher SSA and lower crystallinity tend to yield improved depolymerization when employing leaf compost‐cutinase (LCC‐ICCG) enzymes. This study explored melt extrusion and foaming as pretreatment techniques to modify PET structural properties, using a low‐cost chemical foaming agent (CFA). The monomer conversion rate and efficiency during depolymerization were measured and related to the processing, extrudate micro‐ and meso‐structure, and polyester type. Pretreated PET substrates showed reduced T g , crystallinity, density, and enhanced SSA, resulting in a 90% mass loss for foamed RPET and VPET substrates within 2 days. In contrast, PET with ~30% of cyclohexanedimethanol comonomer exhibited a nearly 50% lower depolymerization rate, with zero BHET production. It indicates that the combination of low crystallinity, low T g , and high SSA leads to improved monomer conversion. These findings emphasize the significance of amorphization and foaming in enhancing PET enzymatic depolymerization.

42 ENGINEERING↗
DOE OSTI2017

A Novel Polyester Fabric Treated with Nanoclay/Nano TiO{sub 2}/PAMAM for Discoloration of Reactive Red 4 from Aqueous Solution Under UVA Irradiation

Here, a commercially available absorbent with a high absorbance capacity (Cloisite{sup ®} 15A) together with the high active nano photocatalyst (AEROXIDE{sup ®} TiO{sub 2} P 25) and polyamidoamine based dendrimer (PAMAM) were immobilized on polyester fabric through simple pad-dry-cure method for removing dye from an aqueous solution. Using three components with good activities toward discoloration expected to produce a substrate with an excellent discoloration capacity. FESEM images with EDX patterns and X-ray diffraction spectra revealed the presence of nanoclay and nano TiO{sub 2} on the surface of the fabric. Discoloration of Reactive Red 4 (RR4) was carried out successfully by addition of a piece of the treated fabric in the dye solution under UVA irradiation. UV–visible spectra of the remaining solutions after discoloration indicated complete discoloration of RR4 solution for several times. The photocatalytic properties of the treated fabric was not changed after consecutive discoloration however the fabric surface was colored due to the presence of nanoclay on the surface acting as the dye absorbent. Graphical Abstract: .

36 MATERIALS SCIENCE↗
DOE OSTI2019

Synthesis and Performance Evaluation of Unsaturated Polyester Blends of Resins and Its Application on Non-woven/Fabric Jute Fibers Reinforced Composites

The present study focuses on the generation of eco-friendly value added product by utilizing bio-based material as reinforced and matrix phase. Processing of soy and alkyd resin as matrix was carried out by utilization of soy flour and Ricinodendron heudelotii oil, followed essential modification in few inferior properties of soy flour resin by blending with alkyd resin. Separate sets of resin were prepared by maintaining 0%, 5% and 10% of alkyd resin in 100 g of soy flour resin respectively in each set to attain a comparative study on performance of prepared sets of resin blend. Subsequently, performance evaluation of polyester blends was evaluated by processing with non-woven/fabric jute fibers reinforced composites. The blend of R. heudelotii oil based alkyd and soy-flour resin in processing of composites was the noval approach of the study. The resins blend were characterized by FT–IR, viscosity and zeta potential measurements while thermo-mechanical analyses, water absorbancy and surface analyses were performed in composites. Significant increases noticed in the viscosity of blend, the blend containing 10% alkyd resin is two times more viscous compared to soy-flour resin. Furthermore, improvement in properties including water absorption, thermo-mechanical properties and better fiber-matrix interfacial adhesion of the composite could be observed. Higher glass transition temperature T{sub g} value i.e. 126.8 °C obtained for composites with 10% blend as matrix might emphasizes on increase of the degree of cross linking provided by the α-eleostearic fatty acid chain moiety. The enhancements in properties indicate extending opportunities for fiber-reinforced composites in several industries including building material, furniture, aerospace, nano etc.

36 MATERIALS SCIENCE↗