Philip Bradford

Research

The Bradford Research group focuses its efforts on the synthesis of ultra-high aspect ratio carbon nanotubes (CNTs) and production of textile like structures from those unique CNTs. The CNT textiles are currently being explored in applications such as composites, sensors, electrodes and filtration.

Please refer to our Research Website for more details on our work.

Academic Degrees

• Ph.D. Materials Science and Engineering, North Carolina State University, 2010
• M.S. Textile Engineering, North Carolina State University, 2007
• M.S. Material Science and Engineering, North Carolina State University,
• B.S. Textile Engineering, North Carolina State University, 2005

Publications

Hybrid Carbon Nanotube Fabrics with Sacrificial Nanofibers for Flexible High Performance Lithium-Ion Battery Anodes

Yildiz, O., Dirican, M., Fang, X., Fu, K., Jia, H., Stano, K., … Bradford, P. D. (2019), JOURNAL OF THE ELECTROCHEMICAL SOCIETY, 166(4), A473–479. https://doi.org/10.1149/2.0821902jes

Real-time impact damage sensing and localization in composites through embedded aligned carbon nanotube sheets

Aly, K., & Bradford, P. D. (2019), COMPOSITES PART B-ENGINEERING. https://doi.org/10.1016/j.compositesb.2018.12.104

Effect of continuous optical fiber bonding on ultrasonic detection using fiber Bragg grating

Wee, J., Hackney, D., Bradford, P., & Peters, K. (2018), In SENSORS AND SMART STRUCTURES TECHNOLOGIES FOR CIVIL, MECHANICAL, AND AEROSPACE SYSTEMS 2018 (Vol. 10598). https://doi.org/10.1117/12.2295833

Experimental study on directionality of ultrasonic wave coupling using surface-bonded fiber Bragg grating sensors

Wee, J., Hackney, D., Bradford, P., & Peters, K. (2018), Journal of Lightwave Technology, 36(4), 932–938. https://doi.org/10.1109/jlt.2017.2769960

Laser-etch patterning of metal oxide coated carbon nanotube 3D architectures

Aksu, C., Ingram, W., Bradford, P. D., & Jur, J. S. (2018), Nanotechnology, 29(33). https://doi.org/10.1088/1361-6528/aac79d

Modifying the morphology and properties of aligned CNT foams through secondary CNT growth

Faraji, S., Stano, K., Akyildiz, H., Yildiz, O., Jur, J. S., & Bradford, P. D. (2018), Nanotechnology, 29(29). https://doi.org/10.1088/1361-6528/aac03c

A silicon-impregnated carbon nanotube mat as a lithium-ion cell anode

Ho, D. N., Yildiz, O., Bradford, P., Zhu, Y. T., & Fedkiw, P. S. (2018), Journal of Applied Electrochemistry, 48(1), 127–133. https://doi.org/10.1007/s10800-017-1140-8

Bi-directional ultrasonic wave coupling to FBGs in continuously bonded optical fiber sensing

Wee, J., Hackney, D., Bradford, P., & Peters, K. (2017), Applied Optics, 56(25), 7262–7268. https://doi.org/10.1364/ao.56.007262

Compressive piezoresistive behavior of carbon nanotube sheets embedded in woven glass fiber reinforced composites

Aly, K., Li, A., & Bradford, P. D. (2017), Composites. Part B, Engineering, 116, 459–470. https://doi.org/10.1016/j.compositesb.2016.11.002

Engineering biorefinery residues from loblolly pine for supercapacitor applications

He, N. F., Yoo, S., Meng, J. J., Yildiz, O., Bradford, P. D., Park, S., & Gao, W. (2017), Carbon, 120, 304–312. https://doi.org/10.1016/j.carbon.2017.05.056

View All Publications

Grants

Large Component, High-quality Composite Fabrication Using Nanocarbon Heating Films

US Navy(10/22/18 - 3/22/19)

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Large Component, High-quality Composite Fabrication Using Nanocarbon Heating Films

Sponsor: US Navy

Start Date: 10/22/18

End Date: 3/22/19

Abstract

Aligned CNT sheets will be utilized to produce heaters Phase 1. Due to the very thin structure of the CNT sheets, it is projected that the final thickness of the heater blankets will be no greater than 0.5 mm. Heaters of size up to 15"x15" will be produced for the sponsor in different configurations. At the same time NC State will work to develop methods for the scale up of the process which would occur in Phase II.

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Nanostructured Heating for Curing of Composites

US Navy(10/23/17 - 3/21/18)

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Nanostructured Heating for Curing of Composites

Sponsor: US Navy

Start Date: 10/23/17

End Date: 3/21/18

Abstract

Aligned CNT sheets will be utilized to produce a heating blanket structure for Phase 1. Due to the very thin structure of the CNT sheets it is projected that the final thickness of the heater blankets will be no greater than 1 mm. Two major approaches will be implemented to determine and their properties and potential for scaling up to large scale blankets. The first approach will use dry wound CNT sheets and will be fabricated and sandwiched in between high temperature films (polyimides or silicones) that have high strength adhesive backing. The second approach would be to wind the CNT sheets and incorporate a heat cured silicone matrix into the sheets before winding. The uncured composite would then be incapsulated in a thin layer of liquid silicone in a molding process to create the electrical insulation of the blanket. The unreacted silicone in the CNT sheets would bond to the encapsulating layers to make a unified blanket with robust integration of the CNT sheets. The procedures for making both types of blankets is relatively simple. Most of NC State's time during Phase I will be spent understanding the configuration of electrical connections to the encapsulated CNT sheets, to tune the properties of the blankets based on the number of CNT layers in the devices and to determine the overall device heating performance. Multiple small devices of dimensions of approximately 6"x2" will be produced to develop the fabrication technique and understand the electrical characteristics. At least two large blankets of 15" x 15" will be provided to Luna for them to demonstrate the out-of-autoclave curing of composites for Phase I.

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Study of Fiber Assemblies for Flexible and Breathable Thermal Conductors

NCSU Advanced Self Powered Systems of Sensors and Technologies (ASSIST) Center(9/01/16 - 8/31/19)

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Study of Fiber Assemblies for Flexible and Breathable Thermal Conductors

Sponsor: NCSU Advanced Self Powered Systems of Sensors and Technologies (ASSIST) Center

Start Date: 9/01/16

End Date: 8/31/19

Abstract

Thermally conductive materials are often used in strategic ways to maximize the temperature differential across thermoelectric energy generators (TEGs) through heat spreaders and heat sinks. Those features are typically made of thermally conductive metals or graphite which are solid and either rigid or semi-flexible depending on the material thickness. To provide the highest ratio of power output to user comfort, ideally TEGs worn on the body should be both flexible and breathable. Flexibility is important for conformability of the device to the body’s contours and durability during body movement. Breathability is important for long term comfort and opens up the possibility of covering a larger surface area of the skin for power generation. This Seed Project aims to support the ASSIST Self-Powered and Adaptive Low Power Platform, and in particular, the efforts to develop next generation TEG devices that are fully flexible and breathable. This will be accomplished through the study and development of textile based heat spreaders and heat sinks which are made up either ultra-high aspect ratio carbon nanotubes (CNTs) and/or highly graphitic carbon fibers. These highly thermally conductive materials will be hybridized with a small fraction of a polymer component in such a way to retain porosity but encapsulate the fibers and retain the desired morphology.

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Carbon Nanotube Foam Composites for Energy Absorption

US Army - Army Research Office(5/01/16 - 1/31/18)

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Carbon Nanotube Foam Composites for Energy Absorption

Sponsor: US Army - Army Research Office

Start Date: 5/01/16

End Date: 1/31/18

Abstract

Viscoelastic polymer foams typically behave in one of two ways. Resilient foams, when compressed, dissipate some of the energy and then can return to their original dimensions. This factor is important for repeat impact events and overall comfort. However, resilient foams have lower mechanical strength, so the amount of energy absorbed is low. Rigid polymer foams are below their glass transition temperature and so impact events tend to crush the cell wall structure allowing for higher strength and energy absorption. These materials must be replaced after each impact event. Polymer foams also exhibit temperature dependent behavior, so a polymer foam optimized for a hot environment may not perform as designed in a cold environment and vice versa. An ideal foam structure for energy absorption applications would have recovery after impact and have temperature independent mechanical properties. This type of foam structure has been demonstrated, in small scale, by the proposer through the use of 3D foam- like assemblies of carbon nanotubes (CNTs). These 3D foam like CNT assemblies will be the basis for new CNT/polymer composite foams which have low density, high compressibility, thermal stability, high energy absorption capability, high level of recoverability and high compressive strength.

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Multifunctional Ultralow Density Structures Based on Aligned Carbon Nanotube Sheets

US Air Force - Office of Scientific Research (AFOSR)(9/30/16 - 9/29/19)

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Multifunctional Ultralow Density Structures Based on Aligned Carbon Nanotube Sheets

Sponsor: US Air Force - Office of Scientific Research (AFOSR)

Start Date: 9/30/16

End Date: 9/29/19

Abstract

The development of low density materials is of critical importance to next generation Air Force structures and technologies. The overarching objective of this work is to extend the state of the art in ultra low density materials and develop fundamental understanding of how the structural parameters of cellular materials based on interconnected nanotubes define their mechanical, electrical, thermal properties as well as their surface functionality.

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Formation of Full Scale Inflatable Laminated Envelope Fabric with Minimum Seam for High Altitude Stratosphere Non-Rigid Airship: Feasibly Study

SCEYE SARL (formerly SCEYE S.A.)(10/01/15 - 3/31/19)

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Formation of Full Scale Inflatable Laminated Envelope Fabric with Minimum Seam for High Altitude Stratosphere Non-Rigid Airship: Feasibly Study

Sponsor: SCEYE SARL (formerly SCEYE S.A.)

Start Date: 10/01/15

End Date: 3/31/19

Abstract

SCEYE S.A. is currently funding (Reference Number 2015-0996) our team to pursue research that deals with a fundamental study to develop high performance inflatable laminated envelope fabrics for high altitude airship. The envelope fabric is characterized by its high strength to weight ratio, low helium and hydrogen permeability and UV resistance. SCEYE S.A. is also funding other researchers to develop lightweight and efficient airship components such as batteries, solar cells, and engine. The Company’s ultimate target is to construct airships with the highest performance with the minimum number of seams across the envelope fabric to dramatically reduce the overall weight of the airship since the inflatable laminated envelope fabric and its seams accounts for the majority of the overall weight of the airship. The current funded project expands over one year (January-December 2015). In this work, small size laminated envelope fabrics are being produced. The constituents of the fabric include high performance fiber reinforced layer laminated with flexible polymer matrix to make the fabric helium/hydrogen tight, surface layer with UV blocking materials, and a layer of carbon nanotube that is infused in the polymer matrix for reinforcement and further UV blocking. This proposal is written in response of solicitation from SCEYE S.A. to conduct a feasibility study on the development of full scale inflatable laminated envelope fabric with zero or minimum seam for the aforementioned airships. The main goal of the proposed research is to conduct a feasibility study on the development of full scale laminated envelope fabric with zero or minimum number of seams for high altitude stratosphere non-rigid airship for long duration and multiple flights.

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Development of Carbon Nanotube Enhanced High Performance Fabrics

SCEYE SARL (formerly SCEYE S.A.)(1/01/15 - 12/31/15)

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Development of Carbon Nanotube Enhanced High Performance Fabrics

Sponsor: SCEYE SARL (formerly SCEYE S.A.)

Start Date: 1/01/15

End Date: 12/31/15

Abstract

High performance fabrics are typically produced from high performance polymers and are typically woven. This work will integrate carbon nanotubes with high performance fabrics to enhance their mechanical and physical properties.

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High Sensitivity Fiber Bragg Grating Sensors through Carbon Nanotube Coatings and Adhesives

US Navy-Office Of Naval Research(5/15/14 - 5/14/17)

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High Sensitivity Fiber Bragg Grating Sensors through Carbon Nanotube Coatings and Adhesives

Sponsor: US Navy-Office Of Naval Research

Start Date: 5/15/14

End Date: 5/14/17

Abstract

We propose to significantly increase the strain transfer from a substrate to fiber Bragg gratings sensors over a broadband of frequencies by directly applying a stiff carbon nanotube (CNT) interface to the optical fiber surface without long-term degradation of the fiber strength and performance. We will work towards this solution using two approaches. The first approach will be to coat the optical fibers with millimeter long, aligned CNTs which will be drawn from special CNT arrays and wrapped onto the fibers. The CNT sheets can be wrapped onto the optical fibers in the dry state for incorporation into adhesive, or wrapped with CNT sheet that is impregnated with a thermosetting polymer system. The second approach will be to replace the adhesive used to mount the sensors onto a composite structure with a stiff CNT adhesive tape with the sensor embedded in the adhesive strips.

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Carbon Nanotube Sheet Electrodes with Inorganic Coatings

National Aeronautics & Space Administration (NASA)(4/07/14 - 12/31/14)

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Carbon Nanotube Sheet Electrodes with Inorganic Coatings

Sponsor: National Aeronautics & Space Administration (NASA)

Start Date: 4/07/14

End Date: 12/31/14

Abstract

This research project is designed to study the deposition of inorganic materials on to aligned carbon nanotube sheets using chemical vapor deposition and atomic layer deposition. During this study the materials will be sent to NASA to be utilized as novel electrode materials.

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Novel Composite Thermal Interface Materials For Heat Transfer in Aerospace Structures

NCSU NC Space Grant Consortium(7/01/12 - 6/30/13)

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Novel Composite Thermal Interface Materials For Heat Transfer in Aerospace Structures

Sponsor: NCSU NC Space Grant Consortium

Start Date: 7/01/12

End Date: 6/30/13

Abstract

Carbon nanotube arrays are promising structures for thermal interface materials due to the high thermal conductivity of carbon nanotubes, continuous nature and high level of alignment. However carbon nanotube arrays are inherently fragile due to their low density. There has been much research interest in infusing carbon nanotube arrays with thermosetting polymer materials to fabricate array composites, which can then be used in thermal applications, but achieving highly conductive composites is limited by the polymer matrix. Producing similar composites with a metal matrix is advantageous due to the higher operating temperature potential and increased thermal conductivity due to the dual phonon conduction mechanisms offered by the carbon nanotube-metal matrix system. These types of composites, however, are much harder to achieve using traditional metallurgical techniques due to carbon nanotube agglomeration, low volume fractions and poor interfacial adhesion between reinforcement and matrix phases. This proposal demonstrates a new processing route for depositing copper metal within carbon nanotube arrays.

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Organizations

• Materials Research Society
• Society for the Advancement of Material and Process Engineering (SAMPE)