- Email: [email protected]
Synthesis of multiscale reinforcement fabric by electrophoretic deposition of amine-functionalized carbon nanofibers onto carbon fiber layers
CARBON
4 8 ( 2 0 1 0 ) 3 2 5 6 –3 2 5 9
available at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/carbon
Synthesis of multiscale reinforcement fabric by electrophoretic deposition of amine-functionalized carbon nanofibers onto carbon fiber layers Alejandro J. Rodriguez, Mauricio E. Guzman, Chee-Sern Lim, Bob Minaie
*
Department of Mechanical Engineering, Wichita State University, 1845 N. Fairmount St., Wichita, KS 67260, USA
A R T I C L E I N F O
A B S T R A C T
Article history:
Deposition of amine-functionalized carbon nanofibers (CNFs) on the surface of carbon
Received 27 January 2010
fibers (CFs) using water as dispersive medium was achieved by a two-stage scalable electro-
Accepted 11 May 2010
phoretic process. The resulting hybrid CNF–CF layers showed uniform distribution and
Available online 16 May 2010
microfiber wrapping of amidized-CNFs not seen when depositing oxidized-CNFs on the same substrate. Such layers provide potential for improving the mechanical properties of advanced composites by covalent bonding between amine and epoxide groups of the CNFs and matrix, respectively. 2010 Elsevier Ltd. All rights reserved.
Due to their unique combination of properties, cost-effectiveness, and availability, carbon nanofibers (CNFs) are viewed as the ideal material to enhance the mechanical, electrical, and thermal properties of advanced composite materials [1– 5]. Electrophoretic deposition (EPD) has proven to be an effective technique for manipulating and depositing large amounts of nanosized particles on different substrates [6– 10]. EPD is a cost-effective and scalable technique in which charged particles suspended in a liquid medium move and deposit onto the counter electrode upon application of a DC electric field. In previous reports, EPD has shown to be effective for depositing carboxylic acid- and amine-functionalized carbon nanotubes (CNTs) on the surface of carbon fiber layers using water and N,N-dimethylformide (DMF) as solvent, respectively [11,12]. Both studies reported successful deposition of CNT which improved the dispersion of the nanomaterials in the fiber; however, the former was for carboxylic-acid CNTs which has low interaction with the matrix, and in the latter study, DMF was used as solvent which is a less environmentally friendly solvent compared to water, consequently limiting the scalability of the process. An important advantage of using EPD to deposit oxidized-CNTs on the surface of carbon fibers is that it does not affect the in-plane tensile
strength of advanced composites made using multiscale reinforcement [11]. Other methods for fabric reinforcement, such as in situ growth of CNT on the surface of carbon fibers by thermal chemical vapor deposition, have shown to reduce the tensile strength of the carbon fiber which in turn is detrimental to the in-plane mechanical properties of the composite part [13]. Few studies have been performed regarding the deposition of CNFs on any type of substrate. Previous research has resulted in deposition of only oxidized-CNFs (O-CNFs) dissolved in DMF, ethanol, and acetonitrile on the surface of indium tin oxide [14]. Other research reported the deposition of O-CNFs on the surface of carbon fiber layers using water as dispersive medium [15]. Although results suggests that O-CNFs are stable in water and deposits readily on the surface of carbon fibers, post EPD images showed uneven distribution of CNFs. It was also reported that composites made of carbon fiber layers with O-CNFs deposited on their surfaces increased the interlaminar shear strength and through-plane electrical conductivity of the parts. In this work, a two-stage electrophoretic process to deposit amine-functionalized CNFs on the surface of carbon fiber layers using water as dispersive media is described. The two-
* Corresponding author: Fax: +1 316 978 3236. E-mail address: [email protected] (B. Minaie). 0008-6223/$ - see front matter 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.carbon.2010.05.018
CARBON
4 8 ( 20 1 0 ) 3 2 5 6–32 5 9
stage methodology is used to synthesize hybrid CNF–carbon fiber layers which can covalently bond with epoxy-based matrix systems through the amine groups grafted on the surface of the CNFs. In addition, it promotes uniform distribution of CNFs on the surface of carbon fiber layers and deposition in hard to reach areas such as inter-tow and intra-tow regions. This configuration gives the hybrid CNF–carbon fiber layers the potential to enhance the mechanical properties of advanced composites by means of fiber bridging when the hybrid CNF–carbon fiber layers are used to manufacture parts. Furthermore, since water is a more abundant, cost-effective, and environmentally friendly solvent than DMF, the process can be scaled to fabricate larger parts. A schematic of the process is illustrated in Fig. 1. In the first step of the process, the as-received CNFs (AR-CNFs) are functionalized with amine groups (A-CNFs). In the second step, the A-CNFs are dispersed in water and deposited on the surface of the carbon fiber layer following a two-stage electrophoretic process. Experimental details can be found in Supplementary information section. The first step in the EPD process is to disperse the A-CNFs in water. For this purpose 190 mg of A-CNFs were initially dispersed in 100 ml of ultrapure water by sonication. After sonication, the mixture was added to the EPD tank which contained ultrapure water and the contents were stirred using mechanical mixing. At this point the pH and electrical conductivity of the solution were measured. The 25 · 17 cm2 epoxy sized carbon fiber layer was clamped between two frames and inserted in the middle of the tank half-way between the metal counter electrodes. Subsequently, a twostage EPD process was applied. In the first stage, a 30 V electric potential was applied between the metal counter electrodes (negative) and the carbon fiber layer (positive) for 40 min. The separation between the counter electrodes and the carbon fiber layer was 4.5 cm. As proved by electrophoretic mobility values, the A-CNFs were positively charged at pH 6 and therefore, the A-CNFs moved towards the negative pole. After the 40 min elapsed, the polarity of the DC electric field was inverted and applied for another 40 min so that the A-CNFs would travel towards the carbon fiber layer. Once the
3257
second stage was completed, the resulting CNF–carbon fiber layer was removed from the EPD tank and vacuum dried. Characterization of the carbon fiber layers before and after electrophoretic deposition of A-CNFs was performed using optical and SEM imaging. Optical images of carbon fibers with and without A-CNFs deposited on the surface (before and after EPD, respectively) are depicted in Fig. 2. The images are shown in pairs from top to bottom indicating the difference between a raw carbon fiber layer (left column) and a carbon fiber layer with A-CNFs deposited on its surface (right column). In this set of images it can be clearly seen that ACNFs were effectively attracted and deposited onto the carbon fiber layer by the two-stage EPD process. Moreover, uniform distribution of A-CNFs was observed across the surface of the carbon fiber layer. This effect was not observed in the case of EPD of O-CNFs where high deposition was achieved without even distribution [15]. This finding is encouraging since one of the most important parameters in this process is the uniform deposition of CNFs, especially in a complex substrate such as a carbon fiber layer. Further insight into the deposition of A-CNFs on the carbon fiber can be gained by observing Fig. 3. The figure shows a set of two images of a single carbon fiber before and after EPD of A-CNFs, respectively. It is clearly observed that after EPD, the A-CNFs are not only deposited on the surface of the carbon fiber, but they also wrapped around the carbon fiber. This wrapping effect has the advantage of increasing the surface area of the fiber which could lead to higher mechanical properties of the final material by means of mechanical interlocking mechanism. This effect was not previously seen in the deposition of oxidized-CNT in water [11] as wells as amidized-CNT in DMF [12] on the surface of carbon fiber layers. Another observation that can be drawn from the SEM images of the hybrid CNF–carbon fiber layers is fiber bridging. This phenomenon can be observed in Fig. 4. On the left side of the figure, an SEM image shows a layer with A-CNFs bridging from one fiber to another. On the right side of the figure, the image shows not only fiber bridging but also deposition of the A-CNF in the inter-tow and intra-tow areas. It is expected
Fig. 1 – Schematic for manufacturing hybrid carbon nanofiber–carbon fiber layers. A two-stage electrophoresis process is used to deposit amine-functionalized carbon nanofibers on the surface of the carbon fiber layers.
3258
CARBON
4 8 ( 2 0 1 0 ) 3 2 5 6 –3 2 5 9
Fig. 2 – (Left column) Optical images of carbon fiber layers before electrophoretic deposition (EPD) of amidized-carbon nanofibers (A-CNFs). (Right column) Optical images of carbon fiber layers after EPD of A-CNFs. Magnifications are 200· for top images and 1000· for bottom images. The images on the right column confirm uniform deposition of A-CNF on the surface of the carbon fiber layers.
Fig. 3 – (Left) Optical image of a single carbon fiber before electrophoretic deposition (EPD) of amidized-cabon nanofibers (ACNFs). (Right) Optical image of a single carbon fiber after EPD of A-CNF. Both magnifications correspond to 500·. Image on the right confirms not only the deposition of A-CNF but also the wrapping of carbon fiber by A-CNF which increases the surface and contact area of the fiber.
that fiber bridging along with covalent bonding between the ACNF, the sizing of the fiber, and the matrix could occur upon heating of the hybrid layer. If this is the case, higher mechanical reinforcement is expected on the matrix–fiber interface. Manufacturing and properties of advanced composites with hybrid A-CNF–carbon fiber layers made following the methodology described herein is currently a subject of investigation. In summary, it was demonstrated that EPD of A-CNFs on the surface of sized carbon fiber layers (25 · 17 cm2) using
water as solvent can result in uniform deposition of the nanomaterial. Water is a more abundant, cost-effective, and environmentally friendly solvent than DMF and other organic solvents. Therefore, the process can be scaled to manufacturing of larger parts. Intrinsic challenges of using water as solvent can be overcome by using low electric fields (<10 V/cm) for shorter processing time, especially when using sized carbon fibers. The resulting hybrid CNF–carbon fiber layers showed uniform distribution of A-CNFs not seen when depos-
CARBON
4 8 ( 20 1 0 ) 3 2 5 6–32 5 9
3259
Fig. 4 – SEM images of amidized-carbon nanofibers (A-CNFs) deposited on the surface of carbon fiber layers. Magnifications are 3700· and 14,000·, respectively. Fiber bridging is observed in both images.
iting O-CNFs on the same substrate. Moreover, the A-CNFs are able to deposit in the inter-tow and intra-tow area and also wrap around the micro-sized fiber. The deposition process described herein provides a simple and scalable method for manufacturing hybrid layers that could covalently bond with epoxy-based matrix systems through the amine groups grafted on the CNFs. The A-CNFs could be used to reinforce advanced composites in weak areas so that properties such as interlaminar shear strength, compressive strength, and delamination toughness can be effectively enhanced. Manufacturing and characterization of multiscale-reinforced composites using fabrics as described herein is underway and will be reported in future publications.
Acknowledgements The authors gratefully acknowledge financial support by the Office of Naval Research (ONR), the National Aeronautics and Space Administration (NASA), the Kansas Technology Enterprise Corporation (KTEC), and Wichita State University (WSU).
Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.carbon.2010.05.018.
R E F E R E N C E S
[1] Sadeghian R, Gangireddy S, Minaie B, Hsiao K-T. Manufacturing carbon nanofibers toughened polyester/glass fiber composites using vacuum assisted resin transfer molding for enhancing the mode-I delamination resistance. Composites Part A 2006;37(10):1787–95. [2] Choi Y-K, Sugimoto K-I, Song S-M, Gotoh Y, Ohkoshi Y, Endo M. Mechanical and physical properties of epoxy composites reinforced by vapor grown carbon nanofibers. Carbon 2005;43(10):2199–208. [3] Tibbetts G, Lake M, Karla S, Rice B. A review of the fabrication and properties of vapor-grown carbon nanofiber/polymer composites. Compos Sci Technol 2007;67(7–8):1709–18.
[4] Iwahori Y, Ishiwata S, Tomoji S, Takashi I. Mechanical properties improvements in two-phase and three-phase composites using carbon nano-fiber dispersed resin. Composites Part A 2005;36(10):1430–9. [5] Rodriguez A, Guzman M, Lim C, Minaie B. Enhancement of mechanical and electrical properties of fiber–reinforced polymer composites through addition of CNF by electrophoretic deposition. In: Proceedings of the SAMPE 2009 technical conference, October 19–22: society for the advancement of material and process engineering; 2009. [6] Besra L, Liu M. A review on fundamentals and applications of electrophoretic deposition (EPD). Prog Mater Sci 2007;52(1):1–61. [7] Boccaccini A, Cho J, Subhani T, Kaya C, Kaya F. Electrophoretic deposition of carbon nanotube–ceramic nanocomposites. J Eur Ceram Soc 2010;48(9):2455–69. [8] Thomas B, Boccaccini A, Shaffer M. Multi-walled carbon nanotube coatings using electrophoretic deposition (EPD). J Am Ceram Soc 2005;88(4):980–2. [9] Du C, Heldebrant D, Pan N. Preparation of carbon nanotubes composite sheet using electrophoretic deposition process. J Mater Sci Lett 2002;21(7):565–8. [10] Cho J, Konopka K, Rozniatowski K, Garcia-Lecina E, Shaffer M, Boccaccini A. Characterisation of carbon nanotube films deposited by electrophoretic deposition. Carbon 2009;47(1):58–67. [11] Bekyarova E, Thostenson E, Yu A, Kim H, Gao J, Tang J, et al. Multiscale carbon nanotube–carbon fiber reinforcement for advanced epoxy composites. Langmuir 2007;23(7):3970–4. [12] Theodore M, Fielding J, Green K, Dean D, Horton N, Noble A, et al. Nanostructured coupling agents for multifunctional composites. In: Proceedings of the SAMPE 2009 technical conference, May 18–21: society for the advancement of material and process engineering; 2009. [13] Sager R, Klein P, Lagoudas D, Zhang Q, Liu J, Dai L, et al. Effect of carbon nanotubes on the interfacial shear strength of T650 carbon fiber in an epoxy matrix. Compos Sci Technol 2009;69(7–8):898–904. [14] Yang Y, Zhao G, Hu S. Direct current electrodeposition of carbon nanofibers in DMF. Electrochem Commun 2007;9(11):2681–5. [15] Rodriguez A, Guzman M, Lim C, Minaie B. Electrophoretic deposition of CNF onto carbon fiber layers for manufacturing of fiber–reinforced polymer nanocomposites. In: Proceedings of the SAMPE 2009 technical conference, May 18–21: society for the advancement of material and process engineering; 2009.
4 8 ( 2 0 1 0 ) 3 2 5 6 –3 2 5 9
available at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/carbon
Synthesis of multiscale reinforcement fabric by electrophoretic deposition of amine-functionalized carbon nanofibers onto carbon fiber layers Alejandro J. Rodriguez, Mauricio E. Guzman, Chee-Sern Lim, Bob Minaie
*
Department of Mechanical Engineering, Wichita State University, 1845 N. Fairmount St., Wichita, KS 67260, USA
A R T I C L E I N F O
A B S T R A C T
Article history:
Deposition of amine-functionalized carbon nanofibers (CNFs) on the surface of carbon
Received 27 January 2010
fibers (CFs) using water as dispersive medium was achieved by a two-stage scalable electro-
Accepted 11 May 2010
phoretic process. The resulting hybrid CNF–CF layers showed uniform distribution and
Available online 16 May 2010
microfiber wrapping of amidized-CNFs not seen when depositing oxidized-CNFs on the same substrate. Such layers provide potential for improving the mechanical properties of advanced composites by covalent bonding between amine and epoxide groups of the CNFs and matrix, respectively. 2010 Elsevier Ltd. All rights reserved.
Due to their unique combination of properties, cost-effectiveness, and availability, carbon nanofibers (CNFs) are viewed as the ideal material to enhance the mechanical, electrical, and thermal properties of advanced composite materials [1– 5]. Electrophoretic deposition (EPD) has proven to be an effective technique for manipulating and depositing large amounts of nanosized particles on different substrates [6– 10]. EPD is a cost-effective and scalable technique in which charged particles suspended in a liquid medium move and deposit onto the counter electrode upon application of a DC electric field. In previous reports, EPD has shown to be effective for depositing carboxylic acid- and amine-functionalized carbon nanotubes (CNTs) on the surface of carbon fiber layers using water and N,N-dimethylformide (DMF) as solvent, respectively [11,12]. Both studies reported successful deposition of CNT which improved the dispersion of the nanomaterials in the fiber; however, the former was for carboxylic-acid CNTs which has low interaction with the matrix, and in the latter study, DMF was used as solvent which is a less environmentally friendly solvent compared to water, consequently limiting the scalability of the process. An important advantage of using EPD to deposit oxidized-CNTs on the surface of carbon fibers is that it does not affect the in-plane tensile
strength of advanced composites made using multiscale reinforcement [11]. Other methods for fabric reinforcement, such as in situ growth of CNT on the surface of carbon fibers by thermal chemical vapor deposition, have shown to reduce the tensile strength of the carbon fiber which in turn is detrimental to the in-plane mechanical properties of the composite part [13]. Few studies have been performed regarding the deposition of CNFs on any type of substrate. Previous research has resulted in deposition of only oxidized-CNFs (O-CNFs) dissolved in DMF, ethanol, and acetonitrile on the surface of indium tin oxide [14]. Other research reported the deposition of O-CNFs on the surface of carbon fiber layers using water as dispersive medium [15]. Although results suggests that O-CNFs are stable in water and deposits readily on the surface of carbon fibers, post EPD images showed uneven distribution of CNFs. It was also reported that composites made of carbon fiber layers with O-CNFs deposited on their surfaces increased the interlaminar shear strength and through-plane electrical conductivity of the parts. In this work, a two-stage electrophoretic process to deposit amine-functionalized CNFs on the surface of carbon fiber layers using water as dispersive media is described. The two-
* Corresponding author: Fax: +1 316 978 3236. E-mail address: [email protected] (B. Minaie). 0008-6223/$ - see front matter 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.carbon.2010.05.018
CARBON
4 8 ( 20 1 0 ) 3 2 5 6–32 5 9
stage methodology is used to synthesize hybrid CNF–carbon fiber layers which can covalently bond with epoxy-based matrix systems through the amine groups grafted on the surface of the CNFs. In addition, it promotes uniform distribution of CNFs on the surface of carbon fiber layers and deposition in hard to reach areas such as inter-tow and intra-tow regions. This configuration gives the hybrid CNF–carbon fiber layers the potential to enhance the mechanical properties of advanced composites by means of fiber bridging when the hybrid CNF–carbon fiber layers are used to manufacture parts. Furthermore, since water is a more abundant, cost-effective, and environmentally friendly solvent than DMF, the process can be scaled to fabricate larger parts. A schematic of the process is illustrated in Fig. 1. In the first step of the process, the as-received CNFs (AR-CNFs) are functionalized with amine groups (A-CNFs). In the second step, the A-CNFs are dispersed in water and deposited on the surface of the carbon fiber layer following a two-stage electrophoretic process. Experimental details can be found in Supplementary information section. The first step in the EPD process is to disperse the A-CNFs in water. For this purpose 190 mg of A-CNFs were initially dispersed in 100 ml of ultrapure water by sonication. After sonication, the mixture was added to the EPD tank which contained ultrapure water and the contents were stirred using mechanical mixing. At this point the pH and electrical conductivity of the solution were measured. The 25 · 17 cm2 epoxy sized carbon fiber layer was clamped between two frames and inserted in the middle of the tank half-way between the metal counter electrodes. Subsequently, a twostage EPD process was applied. In the first stage, a 30 V electric potential was applied between the metal counter electrodes (negative) and the carbon fiber layer (positive) for 40 min. The separation between the counter electrodes and the carbon fiber layer was 4.5 cm. As proved by electrophoretic mobility values, the A-CNFs were positively charged at pH 6 and therefore, the A-CNFs moved towards the negative pole. After the 40 min elapsed, the polarity of the DC electric field was inverted and applied for another 40 min so that the A-CNFs would travel towards the carbon fiber layer. Once the
3257
second stage was completed, the resulting CNF–carbon fiber layer was removed from the EPD tank and vacuum dried. Characterization of the carbon fiber layers before and after electrophoretic deposition of A-CNFs was performed using optical and SEM imaging. Optical images of carbon fibers with and without A-CNFs deposited on the surface (before and after EPD, respectively) are depicted in Fig. 2. The images are shown in pairs from top to bottom indicating the difference between a raw carbon fiber layer (left column) and a carbon fiber layer with A-CNFs deposited on its surface (right column). In this set of images it can be clearly seen that ACNFs were effectively attracted and deposited onto the carbon fiber layer by the two-stage EPD process. Moreover, uniform distribution of A-CNFs was observed across the surface of the carbon fiber layer. This effect was not observed in the case of EPD of O-CNFs where high deposition was achieved without even distribution [15]. This finding is encouraging since one of the most important parameters in this process is the uniform deposition of CNFs, especially in a complex substrate such as a carbon fiber layer. Further insight into the deposition of A-CNFs on the carbon fiber can be gained by observing Fig. 3. The figure shows a set of two images of a single carbon fiber before and after EPD of A-CNFs, respectively. It is clearly observed that after EPD, the A-CNFs are not only deposited on the surface of the carbon fiber, but they also wrapped around the carbon fiber. This wrapping effect has the advantage of increasing the surface area of the fiber which could lead to higher mechanical properties of the final material by means of mechanical interlocking mechanism. This effect was not previously seen in the deposition of oxidized-CNT in water [11] as wells as amidized-CNT in DMF [12] on the surface of carbon fiber layers. Another observation that can be drawn from the SEM images of the hybrid CNF–carbon fiber layers is fiber bridging. This phenomenon can be observed in Fig. 4. On the left side of the figure, an SEM image shows a layer with A-CNFs bridging from one fiber to another. On the right side of the figure, the image shows not only fiber bridging but also deposition of the A-CNF in the inter-tow and intra-tow areas. It is expected
Fig. 1 – Schematic for manufacturing hybrid carbon nanofiber–carbon fiber layers. A two-stage electrophoresis process is used to deposit amine-functionalized carbon nanofibers on the surface of the carbon fiber layers.
3258
CARBON
4 8 ( 2 0 1 0 ) 3 2 5 6 –3 2 5 9
Fig. 2 – (Left column) Optical images of carbon fiber layers before electrophoretic deposition (EPD) of amidized-carbon nanofibers (A-CNFs). (Right column) Optical images of carbon fiber layers after EPD of A-CNFs. Magnifications are 200· for top images and 1000· for bottom images. The images on the right column confirm uniform deposition of A-CNF on the surface of the carbon fiber layers.
Fig. 3 – (Left) Optical image of a single carbon fiber before electrophoretic deposition (EPD) of amidized-cabon nanofibers (ACNFs). (Right) Optical image of a single carbon fiber after EPD of A-CNF. Both magnifications correspond to 500·. Image on the right confirms not only the deposition of A-CNF but also the wrapping of carbon fiber by A-CNF which increases the surface and contact area of the fiber.
that fiber bridging along with covalent bonding between the ACNF, the sizing of the fiber, and the matrix could occur upon heating of the hybrid layer. If this is the case, higher mechanical reinforcement is expected on the matrix–fiber interface. Manufacturing and properties of advanced composites with hybrid A-CNF–carbon fiber layers made following the methodology described herein is currently a subject of investigation. In summary, it was demonstrated that EPD of A-CNFs on the surface of sized carbon fiber layers (25 · 17 cm2) using
water as solvent can result in uniform deposition of the nanomaterial. Water is a more abundant, cost-effective, and environmentally friendly solvent than DMF and other organic solvents. Therefore, the process can be scaled to manufacturing of larger parts. Intrinsic challenges of using water as solvent can be overcome by using low electric fields (<10 V/cm) for shorter processing time, especially when using sized carbon fibers. The resulting hybrid CNF–carbon fiber layers showed uniform distribution of A-CNFs not seen when depos-
CARBON
4 8 ( 20 1 0 ) 3 2 5 6–32 5 9
3259
Fig. 4 – SEM images of amidized-carbon nanofibers (A-CNFs) deposited on the surface of carbon fiber layers. Magnifications are 3700· and 14,000·, respectively. Fiber bridging is observed in both images.
iting O-CNFs on the same substrate. Moreover, the A-CNFs are able to deposit in the inter-tow and intra-tow area and also wrap around the micro-sized fiber. The deposition process described herein provides a simple and scalable method for manufacturing hybrid layers that could covalently bond with epoxy-based matrix systems through the amine groups grafted on the CNFs. The A-CNFs could be used to reinforce advanced composites in weak areas so that properties such as interlaminar shear strength, compressive strength, and delamination toughness can be effectively enhanced. Manufacturing and characterization of multiscale-reinforced composites using fabrics as described herein is underway and will be reported in future publications.
Acknowledgements The authors gratefully acknowledge financial support by the Office of Naval Research (ONR), the National Aeronautics and Space Administration (NASA), the Kansas Technology Enterprise Corporation (KTEC), and Wichita State University (WSU).
Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.carbon.2010.05.018.
R E F E R E N C E S
[1] Sadeghian R, Gangireddy S, Minaie B, Hsiao K-T. Manufacturing carbon nanofibers toughened polyester/glass fiber composites using vacuum assisted resin transfer molding for enhancing the mode-I delamination resistance. Composites Part A 2006;37(10):1787–95. [2] Choi Y-K, Sugimoto K-I, Song S-M, Gotoh Y, Ohkoshi Y, Endo M. Mechanical and physical properties of epoxy composites reinforced by vapor grown carbon nanofibers. Carbon 2005;43(10):2199–208. [3] Tibbetts G, Lake M, Karla S, Rice B. A review of the fabrication and properties of vapor-grown carbon nanofiber/polymer composites. Compos Sci Technol 2007;67(7–8):1709–18.
[4] Iwahori Y, Ishiwata S, Tomoji S, Takashi I. Mechanical properties improvements in two-phase and three-phase composites using carbon nano-fiber dispersed resin. Composites Part A 2005;36(10):1430–9. [5] Rodriguez A, Guzman M, Lim C, Minaie B. Enhancement of mechanical and electrical properties of fiber–reinforced polymer composites through addition of CNF by electrophoretic deposition. In: Proceedings of the SAMPE 2009 technical conference, October 19–22: society for the advancement of material and process engineering; 2009. [6] Besra L, Liu M. A review on fundamentals and applications of electrophoretic deposition (EPD). Prog Mater Sci 2007;52(1):1–61. [7] Boccaccini A, Cho J, Subhani T, Kaya C, Kaya F. Electrophoretic deposition of carbon nanotube–ceramic nanocomposites. J Eur Ceram Soc 2010;48(9):2455–69. [8] Thomas B, Boccaccini A, Shaffer M. Multi-walled carbon nanotube coatings using electrophoretic deposition (EPD). J Am Ceram Soc 2005;88(4):980–2. [9] Du C, Heldebrant D, Pan N. Preparation of carbon nanotubes composite sheet using electrophoretic deposition process. J Mater Sci Lett 2002;21(7):565–8. [10] Cho J, Konopka K, Rozniatowski K, Garcia-Lecina E, Shaffer M, Boccaccini A. Characterisation of carbon nanotube films deposited by electrophoretic deposition. Carbon 2009;47(1):58–67. [11] Bekyarova E, Thostenson E, Yu A, Kim H, Gao J, Tang J, et al. Multiscale carbon nanotube–carbon fiber reinforcement for advanced epoxy composites. Langmuir 2007;23(7):3970–4. [12] Theodore M, Fielding J, Green K, Dean D, Horton N, Noble A, et al. Nanostructured coupling agents for multifunctional composites. In: Proceedings of the SAMPE 2009 technical conference, May 18–21: society for the advancement of material and process engineering; 2009. [13] Sager R, Klein P, Lagoudas D, Zhang Q, Liu J, Dai L, et al. Effect of carbon nanotubes on the interfacial shear strength of T650 carbon fiber in an epoxy matrix. Compos Sci Technol 2009;69(7–8):898–904. [14] Yang Y, Zhao G, Hu S. Direct current electrodeposition of carbon nanofibers in DMF. Electrochem Commun 2007;9(11):2681–5. [15] Rodriguez A, Guzman M, Lim C, Minaie B. Electrophoretic deposition of CNF onto carbon fiber layers for manufacturing of fiber–reinforced polymer nanocomposites. In: Proceedings of the SAMPE 2009 technical conference, May 18–21: society for the advancement of material and process engineering; 2009.