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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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8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Long coir and glass fiber reinforced polypropylene hybrid composites prepared via wet-laid technique

Natural fiber composites offer an advantage in terms of weight saving for many automotive applications; however, many natural fiber composites lack properties to justify substitution for synthetic composites. Hybridizing the natural fiber composites by adding a fraction of synthetic fibers is an innovative approach to provide a balance between composite's performance and weight savings. In this study, coir fiber (40 wt%)-reinforced polypropylene (PP) composites were hybridized by substituting a fraction of coir fiber with glass fiber (0–30 wt%). The composites were prepared using a novel wet-laid technique followed by compression molding, where the fiber length is preserved. The composites prepared by hybridizing PP/coir fibers with glass fibers were light in weight (6–20% lighter compared to 40 wt% glass fiber reinforced PP) with significantly enhanced tensile (strength – 49–182%, modulus – 54–130%), flexural (strength – 41–104%, modulus – 64–193%), and impact properties (157 - 474%) compared to 40 wt% coir fiber reinforced PP composites. Furthermore, the addition of glass fiber (10–30 wt%) to coir fiber reduced the water-absorbing tendency (by 18–74%) of PP/coir fiber composites. All in all, this work has potential applications in automotive, mass transit, and truck applications where natural fiber composites are being investigated as alternatives to metal and/or fully synthetic composites.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Effects of mercerization and fiber sizing of coir fiber for utilization in polypropylene composites

The use of natural fibers as an alternative to synthetic fibers for reinforcing composites is increasing. However, the poor interfacial adhesion between natural fibers and polymer matrices limits their applications. Several approaches have been considered to improve fiber-matrix adhesion via chemical and/or physical treatment. However, the effectiveness of these treatments varies based on the type of fiber, its source, and its composition. Thus, it is imperative to understand the effectiveness of treatment conditions. In this study, we investigated the influence of alkali treatment and fiber sizing on the chemical, thermal, morphological, and mechanical properties of coir fibers and the interface between coir fiber and polypropylene matrix. Further, it was found that using a 5 wt% sodium hydroxide solution for 6 h at room temperature was the optimal treatment condition that led to an improvement in tensile strength by 58%, tensile modulus by 71%, and elongation at break by 37% compared to untreated fibers, and an increment in interfacial shear strength (IFSS) between coir fibers and polypropylene matrix by 32%. The alkali treatment removed the fiber surface impurities, made the fiber surface rough, and enhanced the fiber crystallinity. Sizing of the alkali-treated fiber led to an improvement in IFSS by 87% with no modification of the fiber’s mechanical properties.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Life cycle assessment of coir fiber-reinforced composites for automotive applications

Past decades have seen an increasing prevalence of natural fiber-reinforced composites (NFRCs) due to growing conscientiousness around sustainability and a push towards vehicle lightweighting. The environmentally friendly and sustainable claims of NFRCs need to be validated due to their large variability and variety, particularly where material substitutions are concerned, such as in substituting glass fiber with natural fiber. Additionally, the objective of this work is to determine the cumulative energy demand (CED) and greenhouse gas emissions (GHG) associated with an automotive part (of volume 0.001 m3) made from 40 wt% coir fiber-reinforced polypropylene (PP) and compared with a similar part made from 40 wt% glass fiber reinforced PP. SimaPro v. 9.0.0.49 was used for the analysis, whereas inventory data were collected from databases, such as Ecoinvent 3, Transportation Energy Databook, Greet model 2022, and published papers. The results showed that CED and GHG associated with the coir fiber-reinforced composite part were lower than the glass fiber-reinforced composite part for both cradle-to-gate (~34–40%) and cradle-to-grave (excluding end-of-life) (~24%) analysis.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoIr by Materials Project

IrCo crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Ir is bonded to six equivalent Ir and six equivalent Co atoms to form distorted IrCo6Ir6 cuboctahedra that share corners with eighteen equivalent IrCo6Ir6 cuboctahedra, edges with six equivalent IrCo6Ir6 cuboctahedra, edges with twelve equivalent CoCo6Ir6 cuboctahedra, faces with eight equivalent IrCo6Ir6 cuboctahedra, and faces with twelve equivalent CoCo6Ir6 cuboctahedra. All Ir–Ir bond lengths are 2.67 Å. All Ir–Co bond lengths are 2.57 Å. Co is bonded to six equivalent Ir and six equivalent Co atoms to form distorted CoCo6Ir6 cuboctahedra that share corners with eighteen equivalent CoCo6Ir6 cuboctahedra, edges with six equivalent CoCo6Ir6 cuboctahedra, edges with twelve equivalent IrCo6Ir6 cuboctahedra, faces with eight equivalent CoCo6Ir6 cuboctahedra, and faces with twelve equivalent IrCo6Ir6 cuboctahedra. All Co–Co bond lengths are 2.67 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoIr by Materials Project

IrCo crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Ir sites. In the first Ir site, Ir is bonded to six equivalent Ir and six Co atoms to form distorted IrCo6Ir6 cuboctahedra that share corners with twelve IrCo6Ir6 cuboctahedra, edges with twelve IrCo6Ir6 cuboctahedra, edges with twelve CoCo6Ir6 cuboctahedra, faces with six equivalent IrCo6Ir6 cuboctahedra, and faces with twelve CoCo6Ir6 cuboctahedra. All Ir–Ir bond lengths are 2.65 Å. All Ir–Co bond lengths are 2.58 Å. In the second Ir site, Ir is bonded to ten equivalent Ir and six Co atoms to form distorted IrCo6Ir10 cuboctahedra that share corners with ten CoCo6Ir6 cuboctahedra, corners with twelve IrCo6Ir6 cuboctahedra, edges with eight CoCo6Ir6 cuboctahedra, edges with sixteen IrCo6Ir6 cuboctahedra, faces with sixteen equivalent IrCo6Ir10 cuboctahedra, and faces with eighteen CoCo6Ir6 cuboctahedra. There are a spread of Ir–Ir bond distances ranging from 2.65–5.30 Å. All Ir–Co bond lengths are 2.58 Å. There are three inequivalent Co sites. In the first Co site, Co is bonded to six equivalent Ir and six equivalent Co atoms to form distorted CoCo6Ir6 cuboctahedra that share corners with twelve CoCo6Ir6 cuboctahedra, edges with twelve equivalent IrCo6Ir6 cuboctahedra, edges with twelve CoCo6Ir6 cuboctahedra, faces with six equivalent CoCo6Ir6 cuboctahedra, and faces with twelve equivalent IrCo6Ir6 cuboctahedra. All Co–Co bond lengths are 2.65 Å. In the second Co site, Co is bonded to six Ir and six equivalent Co atoms to form distorted CoCo6Ir6 cuboctahedra that share corners with five equivalent IrCo6Ir10 cuboctahedra, corners with twelve CoCo6Ir6 cuboctahedra, edges with ten IrCo6Ir6 cuboctahedra, edges with twelve CoCo6Ir6 cuboctahedra, faces with six equivalent CoCo6Ir6 cuboctahedra, and faces with fifteen IrCo6Ir6 cuboctahedra. All Co–Ir bond lengths are 2.58 Å. All Co–Co bond lengths are 2.65 Å. In the third Co site, Co is bonded to six Ir and six equivalent Co atoms to form distorted CoCo6Ir6 cuboctahedra that share corners with five equivalent IrCo6Ir10 cuboctahedra, corners with twelve CoCo6Ir6 cuboctahedra, edges with ten IrCo6Ir6 cuboctahedra, edges with twelve CoCo6Ir6 cuboctahedra, faces with six equivalent CoCo6Ir6 cuboctahedra, and faces with fifteen IrCo6Ir6 cuboctahedra. All Co–Co bond lengths are 2.65 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Sizing of discontinuous natural fibers: Effect of sizing approach and sizing concentration on composite properties

Natural fiber reinforced composites (NFRCs) are gaining attention in automotive applications as an alternative to glass fiber composites due to their lightweight and renewable sourcing. However, the inherent hydrophilicity of natural fibers leads to poor compatibility with hydrophobic polymers which adversely affects the mechanical properties of the composites and can limit their application to non-structural parts. Sizing is a common approach used for synthetic fibers to improve the interface between fiber and matrix. However, there is limited study on the sizing of natural fibers, and hence the focus of this work. Here, in this study, two different approaches to sizing discontinuous coir fibers were investigated, namely; (1) ex-situ sizing and (2) in-situ sizing. A commercial polypropylene (PP) based sizing agent was used and the effects of varying sizing solution concentrations (1.5, 2.5, and 3.5 wt%) on the properties of the composites was studied. Results showed that composites prepared via the in-situ sizing process had better fiber–matrix adhesion and improved tensile properties compared to ex-situ sized composites. On studying the effect of different sizing concentrations on composite properties, we found that the tensile strength of the composites increased (by ∼ 42 %) up to 2.5 wt% sizing concentration (in solution) and then decreased. However, the impact strength decreased significantly on increasing the sizing content beyond 1.5 wt% (by ∼ 40 %). Additionally, the study was further extended to investigate the effect of sizing on different NFRCs (coir, banana, and cottonized hemp fiber) where effectiveness of sizing was found to be influenced by the fiber surface morphology.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Discontinuous Aligned Carbon Fiber Intermediates for Automotive and Related Applications

This work focused on preferentially aligning discontinuous carbon fibers in wet-laid or air-laid processes. It is well known that aligned fibers provides higher directional strength and stiffness. Discontinuous fibers further allow higher degree of draw and formability as the gaps in the fibers allow for higher material movement. The current processes are limited in their ability to align carbon fibers during processing. The aligned fibers have several benefits - (a) in applications where chopped fibers can replace continuous fibers for targeted strength and stiffness metrics, but at a substantially reduced cost; (b) they can tolerate deeper draws than continuous fiber composites in thermo-stamping and compression molding processes; (c) they can be tailored for pultrusion and unidirectional applications. Although pultrusion is primarily a process that adopts continuous fibers, stitch bonded entangled discontinuous fibers can provide unique intermediates. This is analogous to natural coir fibers which get aligned and entangled to produce ropes/rods for example, (d) they can be processed in cross-ply and multi-directional formats, like composite laminates. In this work Neenah Paper partnered with IACMI, UT and ORNL to evaluate structure-process-property relationships with Zoltek carbon fiber. A few process parameters such as machine speed, weight basis, fiber length, effect of fiber sizing, direction of mat lay-up etc. were investigated. The produced mats were converted to thermoplastic composite laminates using polyamide 6 (PA6, nylon) resin. The specific objective of this project is to produce a wet-laid nonwoven carbon fiber mat with a high degree of unidirectional fiber alignment, using discontinuous carbon fibers. The report provides details about the processing, characterization, and lower-upper bound properties.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Infrared spectroscopic signature of a hydroperoxyalkyl radical (•QOOH)

Infrared (IR) action spectroscopy is utilized to characterize a prototypical carbon-centered hydroperoxyalkyl radical (•QOOH) transiently formed in the oxidation of volatile organic compounds. The •QOOH radical formed in isobutane oxidation, 2-hydroperoxy-2-methylprop-1-yl, •CH 2 (CH 3 ) 2 COOH, is generated in the laboratory by H-atom abstraction from tert-butyl hydroperoxide (TBHP). IR spectral features of jet-cooled and stabilized •QOOH radicals are observed from 2950 to 7050 cm –1 at energies that lie below and above the transition state barrier leading to OH radical and cyclic ether products. The observed •QOOH features include overtone OH and CH stretch transitions, combination bands involving OH or CH stretch and a lower frequency mode, and fundamental OH and CH stretch transitions. Most features arise from a single vibrational transition with band contours well simulated at a rotational temperature of 10 K. In each case, the OH products resulting from unimolecular decay of vibrationally activated •QOOH are detected by UV laser-induced fluorescence. Assignments of observed •QOOH IR transitions are guided by anharmonic frequencies computed using second order vibrational perturbation theory, a 2 + 1 model that focuses on the coupling of the OH stretch with two low-frequency torsions, as well as recently predicted statistical •QOOH unimolecular decay rates that include heavy-atom tunneling. Most of the observed vibrational transitions of •QOOH are readily distinguished from those of the TBHP precursor. Furthermore, the distinctive IR transitions of •QOOH, including the strong fundamental OH stretch, provide a general means for detection of •QOOH under controlled laboratory and real-world conditions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗