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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Crashworthiness of recycled carbon fiber composite sinusoidal structures at dynamic rates

Fiber reinforced polymer composites are finding applications in the automotive space for structurally critical applications including crash management. The use of recycled carbon fiber reinforcement can greatly reduce carbon emissions. In this study, recycled carbon fiber composites were manufactured into a self-supporting geometry using three matrices: polyphenylene sulfide (PPS), acrylonitrile butadiene styrene (ABS), and a structural epoxy, and subsequently crushed between flat platens at dynamic rates ranging from 4.6 to 9.1 ms -1 at temperatures in a range of -40°C to 80°C. Load-displacement data was used to evaluate their specific energy absorption, crush efficiency, and steady-state crush stress. Further, the energy absorption of the ABS composites was strongly sensitive to temperature, while the PPS composites exhibited strong crush efficiency dependence with both rate and temperature. The epoxy composites exhibited stable crush behavior at dynamic crush rates but exhibited a dramatic reduction in crush efficiency relative to quasi-static tests. The results of this study indicate that recycled fiber composites can achieve very high energy absorption levels (50–80kJkg -1 at room temperature) that make them an excellent alternative to more expensive and less environmentally friendly continuous virgin fiber laminates.

42 ENGINEERING↗
DOE OSTI2026

Performance assessment of 3D printed multi-material energy absorber for automotive bumper: pedestrian lower extremity protection

Designing an energy absorber for automotive bumpers involves balancing low-speed and high-speed impacts to ensure safety, reduce repair costs, and meet regulatory standards. Here, this study explores a novel design using multi-material 3D printing and structural optimization to fabricate a lightweight and cost-efficient energy absorber. The design effectively dissipates energy in low-speed collisions and minimizes force transmission in high-speed pedestrain impacts, helping to meet both safety and performance requirements. The energy absorber design combines 20% carbon fiber-reinforced acrylonitrile butadiene styrene (CF-ABS) and thermoplastic polyurethane (TPU) for optimal stiffness and flexibility. It uses 3D-printed lattice structures optimized through finite element simulations to help meet both low-speed and high-speed impact requirements. Full-scale energy absorbers were 3D-printed using optimized CF-ABS/TPU blends and tested under high-speed impact using the Flexible Pedestrian Legform Impactor (Flex-PLI). For fair comparison, a baseline bumper with a traditional triangular lattice structure, also 3D-printed from the same CF-ABS/TPU materials, was similarly tested. Interestingly, both the optimized and baseline 3D-printed energy absorbers showed nearly identical performance, successfully meeting injury limits. Their performances were also benchmarked against an injection-molded energy absorber. While both 3D-printed and injection-molded designs met injury limits, the 3D-printed absorber exhibited a higher tibia bending moment, indicating an opportunity for further optimization. A Techno-Economic Analysis compared the costs of producing energy absorbers using traditional manufacturing and 3D printing. The analysis highlighted that 3D printing offers cost benefits for low to medium production volumes, with the total cost per energy absorber at ∼ $\$$74, compared to traditional methods that become economical beyond 2000 units.

Additive manufacturing↗
DOE OSTI2022

Constructing a multi-functional polymer network for ultra-stable and safe Li-metal batteries

We report the practical application of lithium (Li) metal electrodes is impeded by Li dendrite growth and unstable solid electrolyte interphase (SEI). Herein, a multi-grafting polymer network, poly(dimethyl siloxane)-g-[poly(poly(ethylene glycol) methyl ether methacrylate)-r-sodium poly(p-styrene sulfonate)] (PPS), is chemically synthesized from reversible addition-fragmentation chain transfer (RAFT) polymerization. With integrated stretchability, ionic conductivity, and mechanical robustness, it serves a dual role to stabilize the Li electrode. As artificial SEI layer, the PPS enables superior electrochemical performance in half cells, symmetric cells, and full cells (PPS@Li/LiFePO 4 , capacity retention of >70% after 600 cycles). Utilized as solid polymer electrolyte (SPE), the all-solid-state Li/SPE/LiFePO 4 full cell delivers excellent cycling performance with an unprecedented capacity retention of 90% over 1,700 cycles at 0.5 C and 81% over 1,000 cycles at 1.0 C. With high-voltage LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) as cathode, the Li/SPE/NMC811 cell exhibits an initial discharge capacity of 162.2 mAh g -1 with a capacity retention of 72% after 200 cycles. The assembled solid-state Li/SPE/LiFePO4 pouch cell with SPE exhibits stable cycling performance over 200 cycles with a capacity retention of 75% and still operates well even after curling, folding, and cutting, demonstrating great potential for achieving ultra-safe and high energy density batteries.

25 ENERGY STORAGE↗
DOE OSTI2024

Chemical specificity in polyzwitterion-polyelectrolyte coacervates: polycations vs polyanions

Aqueous solutions containing polyzwitterions and polyelectrolytes were studied to probe the effects of chemical specificity on the complexation among different types of chains and resulting liquid–liquid phase separation (coacervation). Two kinds of blends were studied. A polyzwitterion, poly(sulfobetaine methacrylate) (PSBMA), was blended with either (1) a polycation, poly(diallydimethylammonium chloride) (PDADMAC), or (2) a polyanion, sodium poly(styrene sulphonate) (NaPSS). Coacervation was observed in both blends after equilibration, while the freshly prepared blend solutions exhibited distinct behavior dependent on the mixing protocols. Mixing solutions of the polyzwitterions and the polycations led to coacervation almost instantaneously. In contrast, the blends containing the same polyzwitterions and the polyanions exhibited no such coacervation by following the same mixing protocol. However, blends prepared after dissolving a solid mixture containing the same polyzwitterions and the polyanions in water exhibited coacervation. Based on the small-angle X-ray scattering (SAXS), cryo-electron microscopy, and rheology measurements, complexation and coacervation in the polyzwitterion-polyelectrolyte blends is rationalized in terms of the entropy change associated with reorganization of solvent (water), which appears to be larger in the polyzwitterion-polycation case in comparison with the polyzwitterion-polyanion blends. These results highlight the importance of chemical specificity and mixing protocols leading to metastable structures in designing a new class of materials based on macromolecular complexation of polyzwitterions.

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

Manganese(II) complexes of 1,1'-bis[(pyridin-2-yl)methyl)]-2,2'-bipiperidine (PYBP): Synthesis, structure, catalytic properties in alkene epoxidation with hydrogen peroxide, and related mechanistic studies

In this study, several manganese(II) complexes with the stereoisomers of ligand PYBP (1,1'-bis[(pyridin-2-yl)methyl]-2,2'-bipiperidine) and different anions were prepared and characterized by X-ray diffractometry. Complex [Mn II (rac-PYBP)] 2+ (1) was found to be an efficient catalyst of alkene epoxidation by hydrogen peroxide in the presence of acetic acid in acetonitrile at room temperature. Cyclooctene was converted to its epoxide with up to 91 % yield, 99.6 % selectivity, and the turnover number of 180 within 5 min. Fast epoxidations of cyclohexene, 1-decene, styrene, and cis-stilbene were also achieved. Isomeric complex [Mn II (meso-PYBP)] 2+ (2) was catalytically inactive under the same experimental conditions. Stopped-flow spectrophotometry and freeze-quenched EPR spectra show that complex 2 is not oxidized by H 2 O 2 in the presence of acetic acid (AcOH) but instead undergoes partial ligand protonation and liberation of the Mn 2+ cations due to the relatively poor chelating ability of ligand meso-PYBP. The rac-PYBP isomer acts as a better ligand and retains the coordinated Mn center when complex 1 is treated with the H 2 O 2 /AcOH mixture in acetonitrile solution yielding a mixture of intensely colored intermediates likely involving Mn III , Mn IV , and Mn V complexes. Magnetic susceptibility measurements, UV–vis and EPR spectra suggest that dinuclear complexes [Mn III 2 (μ-O)(μ-OAc)(rac-PYBP) 2 ] 3+ and [Mn III Mn IV (μ-O) 2 (rac-PYBP) 2 ] 3+ gradually accumulate in the reaction mixture as inactivated states of the catalyst. Complex 1 also causes fast decomposition of hydrogen peroxide into O 2 gas and H 2 O, which competes with the epoxidation of alkenes and requires gradual addition of H 2 O 2 for its efficient use. The catalytic activity of complex 1 is strongly influenced by its counterions and decreases in order ClO 4 - ≈ SbF 6 - > NO 3 – > Cl - indicating that labile ligands in the coordination sphere of Mn are required for the activation of H 2 O 2 .

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

Investigation of chemical stabilities and contact angle of 3D printed polymers with CO 2 capture solvents to enhance absorber performance

Increasing absorption rate in aqueous amine CCS systems is one avenue to decrease capital cost by reducing the overall size of the absorber column. One potential route is by replacing conventional steel packing with custom designed packing made from 3D printed polymers. 3D printing offers endless flexibility in packing designs to better enhance liquid/gas contact, increase CO 2 mass transfer and create compact absorber columns. Additionally, before exploring novel packing designs, it is necessary to identify polymer materials that can be 3D printed while also showing long-term physical and surface property stability upon exposure to corrosive amine solutions. Four polymers that are commonly used for 3D printing were evaluated using CO 2 -loaded amine solution at temperatures typically observed in the absorber column. Three polymers, high-density polystyrene (HDPS), acrylonitrile butadiene styrene (ABS) and nylon were found to be physically stable after 5000 hr of amine exposure at temperatures up to 60 °C. The contact angle (wetting) of water and CO 2 -loaded aqueous amine solution on the polymer surfaces were also stable after exposure to the CO2-loaded amine solution.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Ionic complexation of endblock-sulfonated thermoplastic elastomers and their physical gels for improved thermomechanical performance

Thermoplastic elastomers (TPEs) composed of nonpolar triblock copolymers constitute a broadly important class of (re)processable network-forming macromolecules employed in ubiquitous commercial applications. Physical gelation of these materials in the presence of a low-volatility oil that is midblock-selective yields tunably soft TPE gels (TPEGs) that are suitable for emergent technologies ranging from electroactive, phase-change and shape-memory responsive media to patternable soft substrates for flexible electronics and microfluidics. Many of the high-volume TPEs used for these purposes possess styrenic endblocks that are inherently limited by a relatively low glass transition temperature. To mitigate this shortcoming, we sulfonate and subsequently complex (and physically crosslink) the endblocks with trivalent Al3+ ions. Doing so reduces the effective hydrophilicity of the sulfonated endblocks, as evidenced by water uptake measurements, while concurrently enhancing the thermomechanical stability of the corresponding TPEGs. Chemical modification results, as well as morphological and property development, are investigated as functions of the degree of sulfonation, complexation and TPEG composition. (C) 2020 Published by Elsevier Inc.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Tailored PEDOT:PSS hole transport layer for higher performance in perovskite solar cells: Enhancement of electrical and optical properties with improved morphology

Precise control over the charge carrier dynamics throughout the device can result in outstanding performance of perovskite solar cells (PSCs). Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is the most actively studied hole transport material in p-i-n structured PSCs. However, charge transport in the PEDOT:PSS is limited and inefficient because of its low conductivity with the presence of the weak ionic conductor PSS. In addition, morphology of the underlying PEDOT:PSS layer in PSCs plays a crucial role in determining the optoelectronic quality of the active perovskite absorber layer. This work is focused on realization of a non-wetting conductive surface of hole transport layer suitable for the growth of larger perovskite crystalline domains. This is accomplished by employing a facile solvent-engineered (ethylene glycol and methanol) approach resulting in removal of the predominant PSS in PEDOT:PSS. The consequence of acquiring larger perovskite crystalline domains was observed in the charge carrier dynamics studies, with the achievement of higher charge carrier lifetime, lower charge transport time and lower transfer impedance in the solvent-engineered PEDOT:PSS-based PSCs. Use of this solvent-engineered treatment for the fabrication of MAPbI3 PSCs greatly increased the device stability witnessing a power conversion efficiency of 18.18%, which corresponds to ~37% improvement compared to the untreated PEDOT:PSS based devices.

14 SOLAR ENERGY↗
DOE OSTI2025

Fast-rate joining of thermoplastic composites using integrated additive manufacturing and compression molding process

The integration of additive manufacturing (AM) technology with compression molding (CM), has emerged as a high-performance composite manufacturing technology in recent years. In the AM-CM process, quickly deposited AM preform on a mold undergoes a rapid compaction cycle to fabricate structurally robust composite parts due to highly controlled fiber alignment (from AM) and reduced porosity (from CM). Currently, AMCM-based part size is limited by the size of the mold volume, thus posing a challenge to manufacture scalable parts. Here, this work focuses on joining techniques developed to enable fast rate joining of short fiber-reinforced thermoplastic composite parts using the AM-CM process. Acrylonitrile butadiene styrene resin reinforced with 20 wt% short carbon fiber composites was printed onto a flat mold and pressed under a hydraulic press. Fabricated panels were joined by the (a) mechanical impression at the joining interface and (b) over-molded continuous carbon fiber (CCF) sheet. Tensile tests were performed to characterize the joining strength of both mechanical impression-based joints and CCF over molded joints. Among the mechanical impression-based joints, a U-shape channel allowed the fibers to flow between two joint parts, and 280 % increased mechanical properties were observed. The continuous carbon fiber-based over molded joint CCF showed 350 % increase in tensile strength compared to the butt joints.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Effect of overcharge on Li(Ni 0.5 Mn 0.3 Co 0.2 )O 2 /Graphite cells–effect of binder

Cells based on NMC/graphite, containing styrene-butadiene rubber/carboxymethylcellulose binder in the anodes and pVdF latex/carboxymethykellulose in the cathodes, were systematically overcharged to 100, 120, 140, 160, 180, 250% and 270% state-of-charge. The impact of the binder was characterized by elemental analysis, SEM, and HPLC. These results were compared to similar cells just using the poly (vinylidene difluoride) binder. Not only did the binder impact the rate of transition metal transport from the cathode to the anode, it also had a marked effect on the microstructure and composition of the materials on the anode surface.

25 ENERGY STORAGE↗
DOE OSTI2020

Effect of binder on the overcharge response in LiFePO 4 -containing cells

Two types of small pouch cells based on LiFePO 4 /graphite, one containing a N-methyl pyrrolidinone (NMP)-soluble binder, poly(vinylidene difluoride), and the other an aqueous-soluble binder, styrene-butadiene rubber/carboxymethylcellulose were systematically charged to 100, 120, 140, 160, 180, and 250% state of charge (SOC). The cells were then discharged to 3.0 V at room temperature before being disassembled for postmortem analysis. Microstructural changes in the anode associated with increasing SOC were more pronounced in the aqueous processed cells in comparison to the NMP-processed cells. Dendrite formation was observed on the aqueous-processed anode at 120% SOC, while the NMP-processed anode surface does not show dendrites until 250% SOC. Overall, the aqueous-processed anode surfaces displayed more evidence of microstructural degradation as a function of increasing SOC. In the NMP-processed cells, four organic compounds on the anode surface were found to show a dependence on SOC, while only two displayed a similar dependency in the aqueous-processed cells. The nature of the binder changed the number and composition of the species found at the anode.

25 ENERGY STORAGE↗
DOE OSTI2025

Property optimized energy absorber for automotive bumpers utilizing multi-material and structural design strategies

This study proposes a novel design for automotive bumper using optimized lattice structures and multi-materials to balance low-speed collision and high-speed pedestrian impact performance. Different blends of 20 % carbon fiber-reinforced acrylonitrile butadiene styrene with thermoplastic polyurethane were used to tailor material properties. The energy absorber features lattice structures with customized mechanical responses, created by varying the incline angle θ from 0 to 180°. We conducted 576 finite element simulations on a half-scale model to optimize energy absorption and stiffness, leading to 66 optimized designs that met both low-speed and high-speed impact criteria. Two sub-scale optimized energy absorbers with different peak forces—both meeting low-speed impact requirements—were 3D printed and validated through drop-weight testing. The one with lower peak stress demonstrated a more compliant response, exhibiting approximately 90 % lower initial peak force and an increase in energy absorption of around 33 % (from 24 J to 32 J). Compared to the baseline triangular lattice, the optimized absorber increased energy absorption by 68 % from (19 J to 32 J) and reduced peak stress by 70 %. It also showed near-complete recovery with minimal fractures, making it suitable for repeated use. This design improves safety while offering a lightweight, durable, and cost-effective bumper system.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Effects of surface treatments on ABS mechanical properties from fused filament fabrication

This paper examines the influence of surface treatments on the mechanical properties of acrylonitrile butadiene styrene (ABS) samples printed by fused filament fabrication (FFF). Prior efforts have applied brushing, painting, solvent dipping, infiltration, and vapor smoothing as post-processing surface treatments to improve the mechanical properties of FFF components. Additionally, because FFF can produce components with undesirable surface roughness, mechanical abrasion, epoxy coating, and acetone treatment may increase tensile strength by decreasing stress concentrations. Ridged surface texture may provide desirable tribological or handling properties. Based on these opportunities, this paper investigates abrasive media blasting, epoxy coating, acetone immersion, and ridged texturing surface treatments on the tensile strength and other mechanical properties of FFF ABS samples. ASTM D638-14 Type-I samples were printed, treated on all sample sides, and tested. From tensile tests, the elastic modulus, tensile strength, and fracture strain for both the untreated and treated ABS samples were calculated. For each sample, the surface finish and fracture macromorphology were observed with optical microscopy and the roughness values for the surface finish were calculated from profilometer data. Furthermore, samples were submerged in water and weighed periodically to measure mass changes due to water absorption. From surface profilometry and optical miscopy data, mechanical media blasting, epoxy coating, and immersion in all concentrations of acetone decreased surface roughness. Overall, on average, grit blasting with large beads and epoxy coating led to 2.6% and 1.2% increases in tensile strength, respectively; immersion in 40% acetone led to a 1.9% increase in tensile strength while treatment in 60% and 80% acetone decreased tensile strength by 4.9% and 1.9%, respectively. The study concludes that only grit blasting with large beads, immersion in 60% acetone, and the ridged texture significantly affected the tensile strength.

36 MATERIALS SCIENCE↗
DOE OSTI2023

On electron beam-induced degradation of vinyl ester thermosets

We have demonstrated that electron beam radiolysis induces scissions of the C-O-C bonds along the backbone of the chains of unsaturated polyester thermosets of different compositions based on dicyclopentadiene, isophthalic acid, epoxy vinyl ester, and terephthalic acid. The radiolysis is imminent irrespective of the degree of crosslinking in the thermosets both in neat resins and in the presence of solvents. Electron Paramagnetic Resonance (EPR) results show the formation of the alkoxyl radicals and C-centered radicals as the primary intermediate products of the C-O-C scissions. While the alkoxyl radicals of these resins exhibit very good stability even six months after the irradiation, the C-centered radicals decay very rapidly via their reactions with oxygen that is available either as adsorbed in the resins, dissolved in solvents or from the environment. The radiolytically produced •OH radicals in the unsaturated-ester aqueous solutions play a major role in inducing scissions on the backbone of the polymer chains. The solvated electrons (e s ) from organic solvents, such as dimethyl sulfoxide and isopropyl alcohol, also induce direct scission of the C-O-C bonds, giving rise to the formation of alkoxyl radicals and C-centered radicals. However, a considerable fraction of es is scavenged by the dissolved O 2 to produce O 2 - . Despite the radiation-induced scissions, irradiation of the resins at a dose level of 1000 kGy results in an increase of the glass transition temperature, Tg. This is due to the simultaneous radiation-induced polymerization of the vinyl monomers, toluene, and styrene that are present in the resins. The increase in Tg is observed in all the resins except for the terephthalic polyester resin in aqueous solution, in which the absence of these monomers results in Tg decreasing sharply with irradiation. This work demonstrates that ionizing radiation triggers continuous free radical-chain reactions that lead to the formation of recyclable oligomers.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2023

Experimental and computational study of polystyrene sulfonate breakdown by a Fenton reaction

Experimental studies and ab initio quantum chemistry calculations were combined to investigate the process by which a Fenton reaction breaks down polystyrene sulfonate. The experimental results show that both molecular weight reduction and loss of aromaticity occur nearly simultaneously, a finding that is supported by the calculations. The results show that more than half of the material is broken down to low molecular weight compounds (< 500 g/mol) with two molar equivalents of H 2 O 2 per styrene monomer. The calculations provide insights into the reaction pathways and indicate that at least two hydroxyl radicals are required to cleave backbone Csingle bondC bonds or to eliminate aromaticity. The calculations also show that, of the aromatic carbons, hydroxyl radical is most likely to add to the carbon bonded to sulfur. This finding explains the loss of hydrogen sulfite anion early in the process and also the efficient reduction of Fe(III) to Fe(II) through semiquinone formation. Taken together the experimental and computational results indicate that the reaction is very efficient and that very little H 2 O 2 is lost to unproductive reactions. In conclusion, this high efficiency is attributed to the close association of Fe atoms with the sulfonate group such that hydroxyl radicals are generated near the polymer chains.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Connecting radiation-driven changes in structural, thermal, and mechanical properties in several medical device polymers

Stemming from security threats and shortages in supply, a recent push has emerged to develop alternatives to radioisotope Cobalt-60 gamma radiation for sterilization of polymeric medical products, including electron beam (e-beam) and X-ray machine-based sources. However, before large-scale implementation, the effects of these non-isotope-based methods must be thoroughly investigated from several perspectives, involving their potential detrimental effects on the structural, thermal, and mechanical properties of polymers in medical devices. This paper investigates such effects in commonly used medical device polymers, including polypropylene homopolymer (PPH), polyolefin elastomer (POE), low-density polyethylene (LDPE), acrylonitrile butadiene styrene (ABS), and chlorobutyl rubber (CIIR). To connect radiation-driven changes in polymer structural and thermal properties and corresponding changes in mechanical properties, several characterization techniques were utilized, including gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). We found that the tensile strength of X-ray irradiated PPH, as well as X-ray, e-beam, and gamma irradiated CIIR decreases due to chain scission, which is corroborated by GPC and DMA. The GPC results of LDPE suggest chain scission, but interestingly without a corresponding decline in tensile strength. By comparison, POE and ABS appear to undergo further crosslinking with increasing irradiation dose, which generally strengthens them. Importantly, in the vast majority of the cases, there were small to no changes in properties upon changing radiation technologies (at a given dose), i.e., no radiation source dependence. However, in a few specific cases, radiation method dependencies did arise, for instance, in terms of the molecular weight of PPH being significantly increased upon X-ray irradiation, while the melting temperature, glass transition temperature, and elongation at break reduced compared to gamma. Overall, this study provides valuable insight into radiation-driven chemical and structural changes in polymers that produce changes in physical and functional properties.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Dispersion of modified fumed silica in elastomeric nanocomposites

In polymer nanocomposites, surface modification of silica aggregates can shield Coulombic interactions that inhibit agglomeration and formation of a network of agglomerates. Surface modification is usually achieved with silane coupling agents although carbon-coating during pyrolytic silica production is also possible. Pyrogenic silica with varying surface carbon contents were dispersed in styrene-butadiene (SBR) rubber to explore the impact on hierarchical dispersion, the emergence of meso-scale structures, and the rheological response. Pristine pyrogenic silica aggregates at concentrations above a critical value (related to the Debye screening length) display correlated meso-scale structures and poor filler network formation in rubber nanocomposites due to the presence of silanol groups on the surface. Here, in the present study, flame synthesized silica with sufficient surface carbon monolayers can mitigate the charge repulsion thereby impacting network structural emergence. The impact of the surface carbon on the van der Waals enthalpic attraction, a * , is determined. The van der Waals model for polymer nanocomposites is drawn through an analogy between thermal energy, k B T, and the accumulated strain, γ. The rheological response of the emergent meso-scale structures depends on the surface density of both carbon and silanol groups.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Life cycle cost, energy, and carbon emissions of molds for precast concrete: Exploring the impacts of material choices and additive manufacturing

Molds for precast concrete are commonly used to create simple- to complex-shaped concrete products away from construction sites. These molds are often handmade from wood; however, additively manufacturing (AM, or 3D printing) fiber-reinforced polymer composites is an advantageous alternative, producing significantly more durable, highly complex molds faster, but likely at a higher cost. Here, this study explores the impact of material and production variables on the cost, energy, and carbon emissions of employing composite AM molds over the full lifecycle. The case study employed techno-economic and life cycle assessments to show that using wood flour–poly(lactic acid) or recycled carbon fiber–acrylonitrile butadiene styrene for AM molds can be less expensive than conventional wood molds, especially when considering use phase costs. While wood molds have the least environmental impacts due to wood's higher biogenic carbon sequestration and minimal processing, optimizing AM designs could reduce energy demand, carbon emissions, and cost.

36 MATERIALS SCIENCE↗