Repairable Composites using Carbon Nanotubes
Application Note: Self-Healing Composites
Composites are materials made from a combination of two or more materials to enhance properties like strength, conductivity, etc. Nanocomposites provide large energy savings due to their light weight and tunable properties.1
The light weight makes nanocomposites ideal for increasing efficiency in sectors like transport, automobiles, space exploration, civil engineering, construction, gas, steam turbines, wind power generators and structural components.2,3
Composites with the ability to heal cracks and damage attract special attention. It allows for re-use and reparability on par with metals. This makes them perfect for use in aerospace applications.4 Repairable composites mimic human skin; which can be healed when there are small damages.5 Among these self-healing or repairable polymer composites; Microwave assisted remendable composites are most promising. Microwaves in the 2 to 18 GHz frequency range are best suited for use in these applications.6–8 Single Walled Carbon Nanotubes are ideal microwave absorbers.9 They absorb microwave energy and produce heat because of the electronic losses within them.1,10 The addition of carbon nanotubes to repairable polymers enhances multifunctional properties.
Nanotube converts Microwaves into required amount of heat to induce reversible polymerization of the whole matrix in the system.3 The energy consumption for conventional heating process is higher and the heat transfer is inefficient. The manufacturing cost for the custom heating system is expensive. But in case of microwave heating, the heating happens at molecular level which provides faster heating rate but reduces the energy consumption by 100 times.11 Alongwith energy savings microwave heating reduces processing time.12
Most polymers have poor microwave absorption properties. Materials with low-to-medium dielectric loss factors require no microwave absorber materials while materials with high dielectric loss factors require absorbing materials at the interface. These polymers need an additive to absorb the microwaves and transfer heat. Single Walled Carbon nanotubes are the best such additive; it absorbs the heat and locally heat the surface of the individual parts of the polymer component. Since the heating happens locally; the whole system need not to be heated which thus requiring very less energy. Single Walled Carbon Nanotubes also provides addition mechanical strength. Many studies have showed the use of Single Walled Carbon Nanotubes for microwave welding of thermoplastic, thermoset, and non-polymeric materials both efficiently and effectively.13–16 It has been explained that the small diameter HiPCO Single Walled Carbon Nanotubes are found to be very good microwave absorber. Their ability to convert the microwaves into heat is high compared to normal diameter single walled carbon nanotubes or bigger diameter multiwalled carbon nanotubes.17–19 So incorporating the HiPCO Single Walled Carbon Nanotubes into thermally reversible polymer composites can be effectively handled using microwaves to repair them when they are cracked or damaged.
About NoPo HiPCO Nanotubes:
HiPCO Nanotubes are highly regarded in the scientific community. They have over 12,700 publications dealing with almost every conceivable property of the material. This makes them ideal for use in products.
The NoPo HiPCO reactor is the world’s first and only 4th generation HiPCO (High pressure carbon monoxide) technology. The cutting-edge technology marvel was developed completely in Bangalore, India. Material from the reactor is used for research at NASA, AIST, Nanointegris, IBM, Nikon and others.20,21,22,23
Sosa, E. D., Worthy, E. S. & Darlington, T. K. Microwave Assisted Manufacturing and Repair of Carbon Reinforced Nanocomposites. J. Compos. 2016, e7058649 (2016).
Sosa, E. D., Darlington, T. K., Hanos, B. A., O’ & Rourke, M. J. E. Microwave Assisted Healing of Thermally Mendable Composites. Smart Mater. Res. 2015, e248490 (2015).
Sosa, E. D., Darlington, T. K., Hanos, B. A., O’ & Rourke, M. J. E. Multifunctional Thermally Remendable Nanocomposites. J. Compos. 2014, e705687 (2014).
Aï et al. The Self-Healing Capability of Carbon Fibre Composite Structures Subjected to Hypervelocity Impacts Simulating Orbital Space Debris. Int. Sch. Res. Not. 2012, e351205 (2012).
Wang, Y., Pham, D. T. & Ji, C. Self-healing composites: A review. Cogent Eng. 2, 1075686 (2015).
Thostenson, E. T. & Chou, T.-W. Microwave and conventional curing of thick-section thermoset composite laminates: Experiment and simulation. Polym. Compos. 22, 197–212 (2001).
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Paton, K. R. & Windle, A. H. Efficient microwave energy absorption by carbon nanotubes. Carbon 46, 1935–1941 (2008).
Karthik, P. S., Himaja, A. L. & Singh, S. P. Carbon-allotropes: synthesis methods, applications and future perspectives. Carbon Lett. 15, 219–237 (2014).
Bajpai, P. K., Singh, I. & Madaan, J. Joining of natural fiber reinforced composites using microwave energy: Experimental and finite element study. Mater. Des. 35, 596–602 (2012).
Woo Il Lee & Springer, G. S. Microwave Curing of Composites. J. Compos. Mater. 18, 387–409 (1984).
Lopez de Vergara, U., Sarrionandia, M., Gondra, K. & Aurrekoetxea, J. Polymerization and curing kinetics of furan resins under conventional and microwave heating. Thermochim. Acta 581, 92–99 (2014).
Sung, P.-C., Chiu, T.-H. & Chang, S.-C. Microwave curing of carbon nanotube/epoxy adhesives. Compos. Sci. Technol. 104, 97–103 (2014).
Kwak, M., Robinson, P., Bismarck, A. & Wise, R. Microwave curing of carbon–epoxy composites: Penetration depth and material characterisation. Compos. Part Appl. Sci. Manuf. 75, 18–27 (2015).
Mani, K. B., Hossan, M. R. & Dutta, P. Thermal analysis of microwave assisted bonding of poly(methyl methacrylate) substrates in microfluidic devices. Int. J. Heat Mass Transf. 58, 229–239 (2013).
Singh, B. P. et al. Microwave shielding properties of Co/Ni attached to single walled carbon nanotubes. J. Mater. Chem. A 3, 13203–13209 (2015).
Che, R. C., Peng, L.-M., Duan, X. F., Chen, Q. & Liang, X. L. Microwave Absorption Enhancement and Complex Permittivity and Permeability of Fe Encapsulated within Carbon Nanotubes. Adv. Mater. 16, 401–405 (2004).
Liu, Z. et al. Microwave Absorption of Single-Walled Carbon Nanotubes/Soluble Cross-Linked Polyurethane Composites. J. Phys. Chem. C 111, 13696–13700 (2007).
Dateo, C. E., Gökçen, T. & Meyyappan, M. Modeling of the HiPco process for carbon nanotube production. I. Chemical kinetics. J. Nanosci. Nanotechnol. 2, 523–534 (2002).
Gökçen, T., Dateo, C. E. & Meyyappan, M. Modeling of the HiPco process for carbon nanotube production. II. Reactor-scale analysis. J. Nanosci. Nanotechnol. 2, 535–544 (2002).
HiPco Carbon Single Walled Carbon Nanotubes. Available at: http://www.nanointegris.com/en/hipco. (Accessed: 22nd May 2017)
NoPo Nanotechnologies India Private Limited. NoPo Nanotechnologies India Private Limited Available at: //nopo.in/web/. (Accessed: 22nd May 2017)