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. 2023 Jun 16;6(13):11260–11268. doi: 10.1021/acsanm.3c01266

Scalable High Tensile Modulus Composite Laminates Using Continuous Carbon Nanotube Yarns for Aerospace Applications

Cecil E Evers †, Britannia Vondrasek ‡, Claire N Jolowsky †, Jin Gyu Park †, Michael W Czabaj ‡, Bailee E Ku †, Kaylee R Thagard †, Gregory M Odegard §, Zhiyong Liang †,*
PMCID: PMC10353548  PMID: 37469508

Abstract

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An approach is established for fabricating high-strength and high-stiffness composite laminates with continuous carbon nanotube (CNT) yarns for scaled-up mechanical tests and potential aerospace structure applications. Continuous CNT yarns with up to 80% degree of nanotube alignment and a unique self-assembled graphitic CNT packing result in their specific tensile strengths of 1.77 ± 0.07 N/tex and an apparent specific modulus of 92.6 ± 3.2 N/tex. Unidirectional CNT yarn reinforced composite laminates with a CNT concentration of greater than 80 wt % and minimal microscale voids are fabricated using filament winding and aerospace-grade resin matrices. A specific tensile strength of up to 1.71 GPa/(g cm–3) and specific modulus of 256 GPa/(g cm–3) are realized; the specific modulus exceeds current state-of-the-art unidirectional carbon fiber composite laminates. The specific modulus of the laminates is 2.76 times greater than the specific modulus of the constituent CNT yarns, a phenomenon not observed in carbon fiber reinforced composites. The results demonstrate an effective approach for fabricating high-strength CNT yarns into composites for applications that require specific tensile modulus properties that are significantly beyond state-of-the-art carbon fiber composites and potentially open an unexplored performance region in the Ashby chart for composite material applications.

Keywords: carbon nanotube, CNT, CNT yarn, composite, scalable, mechanical properties

Introduction

Carbon nanotubes (CNTs) have been widely investigated for use in high-performance structural composites because their nanoscale properties suggest that they will exhibit an exceptional strength-to-weight ratio and multifunctionality and have the potential to outperform carbon fiber (CF) in aerospace structures.1−9 However, achieving the theoretically promising properties of CNT composite materials has proven to be challenging, and a new approach to manufacturing (scalable to the structural level) is needed to enable CNTs to be effectively used for the next generation of high-performance composites.7,8,10−12

A wide range of strategies have been pursued to develop structural CNT composites. Many groups have investigated the use of CNTs to fortify traditional CF composites, both by growing CNTs directly on CF to increase the interface strength13−16 and also by dispersing CNTs in resin matrices.17,18 Some studies introduced aligned CNTs into conventional fiber-reinforced composites to achieve greater strength;19−28 such approaches lead only to incremental improvements in properties over current CF composites. Other studies have proposed increasing the alignment of CNTs within composites to achieve improved properties,6,20,22,29−31 but none of these efforts have yielded scalable CNT composite laminates with properties beyond those of CF composites.

CNT yarns have emerged as a promising material form that could address the scalability and alignment challenges associated with CNT-based composites.2,32−41 Vilatela et al.(10) manufactured CNT fiber from an aerogel to achieve a highly aligned CNT network that achieved a specific tensile strength of 1–1.5 N/tex. For comparison, a typical CF/epoxy composite such as IM7/8552 has a specific strength of 2.46 GPa/(g/cm3) and a specific modulus of 98.48 GPa/(g/cm3).42 Dessureault et al.(35) demonstrated that CNT alignment is a critical factor that influences the tensile properties of CNT yarn. Studies have shown that CNT yarn composites using overwrapping aluminum rings for pressure vessels resulted in an 11% increase in weight relative to the bare ring and increased the room temperature breaking load by over 200%.8,39 Despite these tremendous advances in the use of CNT yarns for composites, further breakthroughs in mechanical properties are needed to achieve the ambitious structural design requirements for large-scale aerospace structures.

Several fundamental engineering challenges need to be overcome to fully utilize CNTs for high-performance structural composite applications. Although progress in improving CNT composites has been made at a small scale,1,6,8−10,12,27,30,43,44 high composite properties must be demonstrated in samples large enough to properly evaluate their utility in structural applications. The objective of this research is to develop a new CNT yarn composite fabrication method that provides a high degree of CNT alignment and concentration to yield high-strength and high-modulus composite laminates that can be scaled up for future manufacturing. Here, we report the multiscale microstructure and tensile properties of high-strength CNT 2-ply (two filaments pressed together) yarn manufactured via the floating catalyst chemical vapor deposition (FCCVD) process. Three manufacturing techniques used to produce high-quality unidirectional CNT laminates using aerospace-grade resin matrices with high nanotube concentrations and good resin impregnation while minimizing microscale voids are then described. The manufacturing techniques enable the scale up of the manufacturing to laminate-scale composite panels, which allows for conducting engineering-scale tests to directly compare the properties of the CNT laminates with state-of-the-art CF composite materials currently used in aerospace primary and secondary structures.

Results and Discussion

This research used commercially available MIRALON high-strength 2-ply (two filaments pressed together) CSY CNT yarn, which was manufactured by Nanocomp Technologies, Inc. (Nanocomp), now part of Huntsman Advanced Materials. The typical CNT yarn length range was 150–500 m with a linear density range of 7–10 tex (g/km). The CNT yarns had irregular cross-section geometries, as shown in Figure 1a.

Figure 1.

Figure 1

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2-ply CNT yarn surface and cross-section: (a) typical yarn cross-section (b) alternating layer microstructures with nanoscale particles of residual catalyst and graphitic self-assembled CNTs, (c) CNT deformation types, and (d) schematic illustrating CNT yarn laminates.

High-resolution transmission electron microscopy (TEM) studies revealed detailed molecular structures of the yarn materials. Figure 1b illustrates the alternating-layer microstructures of aligned CNTs coming from the cross-section (bright circular shapes) and misaligned CNTs (long, gray lines) as well as relatively uniform sizes of the residual catalyst particles (black dots appearing from Z contrast). The misaligned CNT layers could also include amorphous carbon and other organic impurities formed during the manufacturing process.35,45,46 Previous investigations in MIRALON CNT yarns as well as in other CNT yarns found collapsed CNTs formed dog-bone-like graphitic crystal molecular structures, which proved to be a critical contributor to their high strength.20,22,47,48Figure 1b,c displays the unique CNT self-assembling phenomenon observed in the CNT yarns investigated in the study, similar to those investigations. Large diameter tubes with a smaller number of walls tend to collapse at diameters above 7.8 nm for double-walled CNTs (DWCNTs). During the manufacturing process, we hypothesize that it is thermodynamically favorable for tubes to collapse and form the unique self-assembly as observed in Figure 1b,c.22,29,49,50 The dense graphitic self-assembled microstructure was composed of partially deformed small diameter multi-walled CNTs (MWCNTs) (3–7 nm) and fully collapsed and graphetically stacked large diameter DWCNTs (8–12 nm). Such graphitic self-assembly reduces the voids between CNTs and ensures a high degree of alignment along CNT lengths. DWCNT and MWCNT collapse and self-assembling appears to provide improved interactions and load transfer among nanotubes with different diameters as they maximize graphitic contact between CNTs. These molecular structures and features lead to the high specific tensile properties of the yarns (see more CNT assembly examples in the Supporting Information). Focused ion beam (FIB) 3D tomography and TEM were used to study the yarn void content. The yarns had nanoscale pores with a 1.9 vol % isolated void concentration within the specimen. Some pores were formed along the longitudinal direction of the yarn, but most were small and isolated. These results demonstrate the high-density packing of CNTs in the yarns (see more FIB 3D tomography details in the Supporting Information).

CNT yarn laminates were fabricated with these CNT yarn materials and selected aerospace resin matrixes, as shown in Figure 1d.

Figure 2a shows a thermogravimetric analysis (TGA) curve obtained from the as-received CNT yarn. The large mass loss of CNTs over the temperature range from about 500 to 750 °C indicates a wide range of CNT diameters, which agrees with the TEM results presented in the previous section. The residual catalyst and char were about 10–15 wt %, with some variation from batch to batch.

Figure 2.

Figure 2

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TGA and WAXS analyses: (a) TGA analysis showing a wide nanotube degradation temperature range (500–750 °C); (b) narrow fwhm of 7.3° of the CNT yarn compared to PAN-based and pitch-based CF; (c) full set of tensile stress–strain curves, and (d) and (e) typical pullout failure modes of the yarns.

The degree of alignment of the CNT yarn was investigated using wide-angle X-ray scattering (WAXS). Figure 2b shows the integration of the WAXS scattering intensity in the 20° < 2θ < 30° range including the (002) peaks. The CNT yarn achieved a narrow distribution in the azimuthal angle with full width at half maximum (fwhm) of 7.3°, which was less than PAN-based CF (31.6°) but higher than pitch-based CF (5.9°). Another difference was the higher background scattering intensity of the CNT yarn, around 0.3, which was much greater than that of CF, which was less than 0.03. This higher background was primarily due to the presence of amorphous carbon, impurities, and misaligned CNTs.

Based on polarized Raman spectroscopy with angular dependence and X-ray scattering from azimuthal distribution, anisotropy and alignment of CNT materials have been estimated.20,22,47,51 Graphitic layer alignment from X-ray scattering and Herman’s orientation factor have been used to estimate the alignment in CF.52,53 In those studies, a highly aligned sample had a small fwhm and narrow distribution. This technique would indicate that CNT yarn has better alignment than PAN-based CF. However, considering the X-ray background from amorphous carbon and the smaller Raman intensity anisotropic ratio (I∥/I⊥), we estimate the degree of alignment in CNT yarn to be around 70–80%. The high degree of alignment of CNTs and the graphitic features in the CNT yarns that are aligned along the yarn axis provide the essential microstructures to achieve excellent mechanical properties; however, there is still room for improvement to be more comparable to high alignment and graphitization degrees in carbon fiber materials to further enhance the mechanical properties.

Figure 2c shows the typical specific stress–strain curves of single 2-ply CNT yarns using a capstan fixture with a gauge length of 120 mm. For some specimens, a stepwise failure was observed when one ply failed before the other, rather than both failing simultaneously. Due to the irregular shape of the yarns, the linear mass density (g/km or tex) was used to calculate the specific tensile properties. The yarn samples exhibited a specific strength of 1.77 ± 0.07 N/tex and a specific modulus of 92.6 ± 3.2 N/tex. We consider these results to be an apparent modulus because strain was calculated with crosshead displacement, which causes this value to be underestimated. Figure 2d,e shows the failed ends of the representative specimens. The numerous pullouts and curved CNT ribbons indicate poor load transfer between the CNT bundles and possible slippage among CNT assemblages since failure will occur between aligned CNT bundles.20,34,35 (see the Supporting Information for the detailed test setup and parameters.).

Achieving excellent mechanical performance of fiber-reinforced composites requires a high degree of reinforcement alignment, low void and defect content, high fiber concentration and a strong reinforcement/matrix interface. These principles also apply on CNT-reinforced composites.6,22 In this research, the CNT yarn filament winding process previously reported by our group54 was modified to manufacture unidirectional CNT yarn laminates with a high degree of CNT alignment and dense packing. As shown in Figure 3a, the yarns were continually wound under tension onto a multifunctional mandrel. A densification treatment was performed, shown in Figure 3b. As shown in Figure 3c the yarns were impregnated with resin and cured. Figure 3d shows the result: two identical unidirectional laminates measuring 80 mm × 38 mm × 0.2 mm. This procedure delivered high-quality, reproducible, and scalable composite laminates, compared to previous efforts.3,5,22,40Table 1 lists the major manufacturing parameters and properties of the manufactured laminates using different resin matrices and impregnation/curing methods.

Figure 3.

Figure 3

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Unidirectional CNT laminate manufacturing: (a) filament winding CNT yarns on a mold; (b) densification treatment; (c) impregnation and curing with resin; and (d) resultant laminates.

Table 1. Composition and Properties of Unidirectional CNT Composite Laminates.

laminate resin matrix resin application method glass transition (°C) CNT weight fraction (wt %) density (g cm–3) thickness (μm) strength (MPa) modulus (GPa)
1 CYCOM 5250-4 film 350 81 1.53 150.6 ± 10.4 2106 ± 150 301 ± 50
2 AroCy XU 371 Film 341 83 1.38 192.7 ± 4.3 2190 ± 158 329 ± 42
3 Araldite MT 35610 Film 381 81 1.42 197.1 ± 10.2 2365 ± 118 353 ± 33
4 CYCOM 5250-4 autoclave 325 76 1.29 276.8 ± 27.9 1804 ± 189 246 ± 31
5 CYCOM 5250-4 30 wt % resin solution 350 77 1.38 255.2 ± 11.6 2031 ± 110 281 ± 24
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Complete impregnation of the resin was anticipated to be a challenge since the nanotubes were densely packed within CNT yarns, as shown previously. Therefore, three different resin infiltration techniques were performed to evaluate effective impregnation of the resin into the yarn stacks and nanoscale pores within the yarns. Resin was applied as a thin film to the surface of the yarn stack, as a solution with a solvent, and as a thin film with a vacuum bag in an autoclave process.

Simulations have previously indicated that benzoxazine and cyanate ester resins may have strong compatibility with CNT materials;55−57 consequently, three different types of resin matrices were evaluated: CYCOM 5250-4 bismaleimide (BMI) (provided by Solvay), Araldite MT 35610 benzoxazine, and AroCy XU 371 cyanate ester (both provided by Huntsman).

Figure 4 shows the microstructure of laminate 1 from the table. Figure 4a is a photograph of a CNT yarn laminate. Figure 4b shows a stitched SEM image of roughly 4 mm of a representative composite laminate’s cross-section. From the figure, it is clear that the panel thickness and CNT yarn packing are consistent along the width of the specimen with no noticeable microscale voids, despite the large and irregular cross-sections of the CNT yarns. Figure 4c is a higher-magnification SEM image of the laminate cross-section, clearly showing the interfaces between CNT yarns with resin-filled spaces between yarns. The pressures applied during manufacturing caused the yarn cross-sections to conform to each other to maximize packing while still allowing for a small amount of resin to remain in the interior of the composite. All panels achieved a similar microstructure; the only notable difference was laminate 4, which had a slightly lower density, possibly due to a resin-rich layer, which formed on the laminate surface from the vacuum bagging process (additional laminate cross-section images can be found in the Supporting Information).

Figure 4.

Figure 4

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Microstructure of the CNT yarn laminate: (a) photograph of CNT yarn laminate; (b) SEM cross-section of the laminate showing densely-packed CNT yarns; and (c) higher-resolution SEM image of the laminate cross-section with the interfaces between individual CNT yarns clearly visible.

The resulting laminates were characterized using dynamic mechanical analysis (DMA) and tensile testing. Figure 4 clearly shows a high CNT concentration in the laminates; consequently, the resin content was low. Based on TGA analysis, which is presented in Figure 5a, panel 1 achieved ∼80 wt % CNT concentration, indicated by the ∼8 wt % resin and impurities, and 12 wt % remaining catalyst and residues. DMA results, shown in Figure 5b, show a storage modulus as high as 147 GPa and a Tg at 350 °C, which indicates a fully cured sample.

Figure 5.

Figure 5

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TGA and DMA analysis: (a) TGA result showing ∼80 wt % CNT concentration; and (b) DMA result indicating high storage modulus and 350 °C Tg.

An ASTM standard does not exist for this type of material at this scale, so we developed an intermediate scale method.58,59 Tensile testing was performed on laminate specimens with a gauge length of 25 mm. Figure 6a shows the tensile testing setup. Figure 6b shows the progression of a typical sample failure from initial longitudinal splitting of the specimen to eventual failure and brooming of the individual CNT yarns. Specimen splitting early in the loading can introduce artifacts into the optical strain measurement, which might lead to errors in the modulus calculation. To account for this, we applied a linearity criterion (R2 > 0.995 for a linear fit), and only the loading segments that met the criteria were included in the average modulus calculation for that laminate. The resulting processing parameters and tensile properties of the laminates are summarized in Table 1.

Figure 6.

Figure 6

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Tensile test setup and tensile specimen failure mode: (a) Tensile test setup and optical extensometer marks for strain measurement; (b) sequence of specimen tensile failure showing longitudinal splitting early in the loading process, followed by yarn breakage and brooming; and (c) composite electron micrograph of a failed tensile specimen.

Failure occurred in two parts: first as inter-yarn failures as the composite splits apart, then as intra-yarn failures as the individual yarns fail. Figure 6c is a composite SEM image of a failed CNT laminate specimen. The failure mode indicates a susceptibility to shear- and peel-type failure, and a lack of adequate load transfer in the directions perpendicular to the yarn axis, as expected given the low resin content and early onset of longitudinal splitting observed in Figure 6b. We hypothesize that increasing the resin content will increase the transverse strength and thereby possibly increase the laminates’ strength and reduce the variation observed.

After initial splitting, the laminates failed in an intra-yarn mode as the individual yarns failed. Since resin cannot penetrate the interior of the yarn, most graphitic interfaces inside the yarn interact only through Van der Waals and frictional forces. This is consistent with the morphology presented in Figure 1. The results indicate that if resin could penetrate deeper to the interior of the yarn network, then intra-yarn load transfer might be increased.20,45,46

There may be two major reasons for the dramatic increase modulus properties between CNT yarns and CNT yarn laminates. First, adding a thin coat of resin to the outside of a CNT yarn has been shown to increase the modulus by up to 20% due to limited resin penetration into the out-layer of CNT bundles in yarns.46,60−62 Second, combining the yarns together and densifying them together with resin during the impregnation and curing process could lead to further resin penetration due to local confinement of resin among densely packed CNT yarns, as well as additional CNT self-assembly and alignment improvements20,22,29 under pressure and lubrication with low-viscosity liquid resin. These elements may improve load transfer among CNT yarns as well as CNT bundles within CNT yarns to bring significant property improvements; however, these hypotheses require further study and validation. Different molecule sizes and rheology properties of the selected resin matrices could also play a critical role in enhancing load transfer among CNT to CNT and CNT to resin matrix in the resultant composites, which also requires further study. Given this, we expect functionalization to further improve the properties of the composite.

Figure 7 compares the specific tensile properties of the unidirectional CNT laminates with state-of-the-art unidirectional CF/epoxy composite materials with a standard fiber volume fraction of 60%. The CF/epoxy composite values are adopted from the manufacturer’s datasheets and rule-of-mixture calculations for the standard 60% fiber volume fraction. For all of the CNT laminates investigated, the specific tensile modulus was most comparable to the modulus of the unidirectional M60J composite, which is made with high-modulus fibers,63 and is state-of-the-art in terms of composite specific tensile stiffness. The CNT laminates made with cyanate ester and benzoxazine resin exceeded the specific modulus of M60J by 7.6 and 19.1%, respectively. The specific moduli for all of the CNT laminates investigated were nearly double the specific moduli of the unidirectional IM7 and T1100G CF composites,64,65 both of which are widely used in the aerospace industry. In addition to the high modulus, the CNT yarn laminates have specific strengths that are comparable to IM7 composites and superior to M60J composites. The benzoxazine and cyanate ester resin laminates demonstrated better tensile properties than those made with BMI, which agrees with the molecular simulation results of resin/CNT interface interactions.56,57

Figure 7.

Figure 7

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Combined high specific tensile modulus and strength unidirectional CNT yarn laminates compared to the state-of-the-art high-modulus and high-strength CF composites (CFRPs) (CFRP performance is calculated based on the manufacturers’ datasheets; see the Supporting Information for more information).

These results show that the CNT-reinforced composites achieved an attractive combination of high specific strength and modulus properties when compared to the industry-standard CF/epoxy composites, demonstrating their potential to open a new performance region in the Ashby chart for high-performance composite applications.

Conclusions

An effective engineering approach to fabricate scaled-up, high tensile performance unidirectional CNT yarn laminates has been developed. These laminates achieved a CNT yarn concentration larger than 80 wt.% and high degree of CNT alignment as well as a consistent microstructure without noticeable voids. A specific modulus of 256 GPa/(g cm–3), higher than that of the state-of-the-art unidirectional high-modulus M60J CF/epoxy composite, was achieved, and a specific strength of 1.71 GPa/(g cm–3), comparable to the unidirectional IM7 CF/epoxy composite, was demonstrated. This result was from the laminate using benzoxazine resin; simulation results have indicated that benzoxazine would have the highest interface friction.57 The specific modulus of laminate 3 was 2.76 times beyond the apparent specific modulus of the CNT yarns, which is not observed in traditional CF composites. Further study is needed to fully understand this unique phenomenon.

This combination of both high specific modulus and strength is unique among the high-performance composites and opens a new area in the Ashby chart with very attractive scalability using commercially available continuous CNT yarns and widely used composite manufacturing processes. Despite this achievement, the resultant composite properties still fall short of the theoretical maxima due to lack of load transfer within yarns, as evidenced by low resin content and explosive composite failure; therefore, these materials would only be attractive in potential aerospace structural applications where high tensile performance is needed at this research stage.

Methods

Helios G4 UC (Thermofisher Scientific) was used for SEM and TEM sample preparation using FIB. Auto Slice and View (ASV) was performed in the Helios which collected cross sections of CNT yarn and reconstructed them using Avizo software. Pores were marked and segmented from the software, and subsequently the resulting pore structures and statistics were acquired. High-resolution TEM images were acquired using JEM-200cF (JEOL). Phenom XL Desktop SEM (Thermofisher Scientific) was also used for large area mapping of the composite laminate cross section.

TGA of the CNT yarn laminates was performed under an air environment with a 15 °C/min heating rate using a TA Instruments Q50 TGA. Multiple steps of weight decrease can be observed as well as the Fe catalyst residue. Smaller-diameter CNTs decompose earlier than large-diameter CNTs due to the higher reactivity of smaller-curvature CNTs. This implies that different diameters of CNTs coexist in the sample.

DMA of the laminates was performed with a TA Instruments Q800 with a frequency of 1.00 Hz with a thin film fixture ramping at 5 °C/min to 400 °C. Afterward, the plot was smoothed.

X-ray scattering was measured using a Nanostar system with an Incoatec IμS microfocus X-ray source operating at 45 kV and a Vantec 2D-detector (Bruker). The primary beam was collimated with cross-coupled Göbel mirrors and a three pin-hole system providing a Cu Kα radiation beam (λ = 0.154 nm) with a beam size of about 0.15 mm at the sample. WAXS patterns were recorded on the image plate and read with a FLA-7000 scanner.

The CNT yarns were tested on a Shimadzu Autograph AGS-X mechanical test system using Grip-Engineering Thümler GmbH TH76-1+Ko capstan grips with a 2.5 cm diameter and 500 N load cell. A gauge length of 120–130 mm was used with a preload of 0.1– 0.15 N. The samples were tested at a loading rate of 3 N/min until complete fracture occurred. Strain was calculated by crosshead displacement. A sample was considered valid only if it failed in the gauge length. Fracture surfaces were imaged with a Phenom XL desktop SEM.

Unidirectional laminates were cut into coupon-shaped tensile specimens using an x-acto knife. The resulting specimens were 2–3 mm wide and 80 mm long. The specimen thickness varied with the thickness of the laminate as detailed in Table 1. Specimen width was measured optically using a Dino-Lite Edge Digital Microscope and DinoCapture 2.0 software. Seven width measurements were taken along the gauge length of the specimen and averaged to obtain the specimen width. A Mahr Micromar 40 EWR(i) Digital Micrometer was used to measure the specimen thickness at three points along the gauge length. After measuring, matte white Chartpak Graphic Tape with a width of 1/32″ was applied to the specimen as a marker for the optical extensometer. An aluminum jig was used to obtain a consistent gauge length between tape marks of 25 mm. A very small amount of Aleene’s Quick Dry Tacky Glue was applied to help the tape marks adhere better to the specimen. An Instron 5969 load frame was used for testing. It was equipped with a 50 kN Instron load cell and MTS 646 hydraulic collet grips with 1/2” inner diameter. Aluminum grip inserts were fabricated from small sections of 1/2” diameter semi-circular aluminum rod stock. The gripping surface of the inserts was sanded to adjust the insert size to account for variation in specimen thickness and to help prevent specimen slip. The specimen cross-section was assumed to be rectangular for the purpose of calculating the applied stress. The testing method consisted of a 20 N preload, followed by a loading ramp to 1300 MPa to measure modulus. After that, the specimen was unloaded to 300 MPa stress and then loaded to failure. The loading rate for all segments of the test was 0.3 mm/min. During testing, the displacement of the tape marks was measured with an Epsilon One optical extensometer. Eight specimens were tested from each laminate. The modulus was calculated for all three loading segments (load, unload, and reload) over the range from 400 to 1200 MPa.

CNT yarn laminate properties were compared with unidirectional CFRPs via data sheets supplied by the manufacturers, which indicate 60 vol % and unspecified epoxy resin matrix. The CF density was supplied; however, the density of the composite was not reported, thus it was calculated via rule of mixtures assuming a density of 1.3 g cm–3 for the resin matrix.

Acknowledgments

This work was supported by The Institute for Ultra-Strong Composites by Computational Design [US-COMP, NASA NNX17AJ32G, which is a NASA Space Technology Research Institute (STRI)]. We would like to thank E. Siochi and the NASA nanotube composite team for their support and guidance. TEM work was performed at the National High Magnetic Field Laboratory, which is supported by National Science Foundation Cooperative Agreement no. DMR-1644779 and the State of Florida. We also would like to thank Cytec/Solvay and Huntsman for providing nanotube yarn and resin matrix support as well as guidance. We appreciate the support of the Solvay Doctorial Fellowship. Finally, we would like to thank J. Horne for offering his expertise in composite manufacturing processes and B. Park for assistance in figure preparation.

Supporting Information Available

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsanm.3c01266.

  • Additional TEM images, Raman spectroscopy, yarn testing, and laminate manufacturing details (PDF)

Author Contributions

G.M.O. acquired funding. C.E.E., C.N.J., B.E.K., and Z.L. developed the laminate manufacturing technique. C.E.E., B.E.K., and K.R.T. manufactured the laminates. C.E.E., J.G.P., and K.R.T. performed yarn characterization. B.V. and M.W.C. developed the laminate testing technique and performed laminate mechanical testing. C.E.E. drafted the manuscript, and all authors participated in manuscript preparation. All authors have given approval to the final version of the manuscript.

The authors declare no competing financial interest.

Supplementary Material

an3c01266_si_001.pdf (1.3MB, pdf)

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