Miralon - It's All About The Network

Posted by Jenn Houston on Aug 23, 2017 9:41:31 AM
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Carbon Nanotubes miralon Graphene Network effect

In the early 2000s there was tremendous hype around the promise of carbon nanotubes. The initial excitement has largely faded as the properties of discrete nanotubes fell short at the macro level. Recently, attention has turned to the potential of graphene. Graphene carries with it an equally impressive list of properties, but has fundamental limitations as a 2 dimensional structure.

Miralon, by contrast, is a continuous, interconnected, 3-dimensional network of carbon tubes and bundles that has successfully demonstrated application level performance. The Miralon network effect is evident in its strength, electrical conductivity, thermal conductivity, corrosion resistance and mechanical damping.  

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The Difference Between CNTs, Graphene and Miralon:

Carbon Nanotubes

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Carbon nanotubes (CNTs) are best described as seamless cylindrical hollow fibers, comprised of a single sheet of pure graphite (a hexagonal lattice of carbon, similar to a chain link fence), having a diameter of 0.7 to 50 nanometers with lengths generally in the range of 10’s of microns.  Being a hollow tube comprised entirely of carbon, they are also extremely light weight.      

The bond holding the carbon atoms together is very strong, plus the hexagonal pattern of the atoms themselves gives rise to a phenomenon known as electron delocalization.   This means that under the right conditions electrical charge can move freely in a nanotube.   The regular arrangement of the atoms also can vibrate in ways that effectively move heat through the tube, so thermal and electrical conductivity are high. At the individual tube level, these unique structures exhibit: 200X the strength and 5X the elasticity of steel; 5X the electrical conductivity, 15X the thermal conductivity and 1,000X the current capacity of copper; at almost half the density of aluminum.

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While these properties are impressive at the individual nanotube scale, the lack of an interconnection between the nanotubes is a fundamental limitation.  There are also health and safety concerns regarding safe handling of CNT powders given their small size.  To date, the practical use for CNTs has largely been as an additive.

Graphene

Graphene is a single sheet of carbon atoms arranged in a hexagonal honeycomb pattern in which one atom forms each vertex. It is the basic structural element of other allotropes including graphite, charcoal, carbon nanotubes and fullerenes. It can be considered as anindefinitely large aromatic molecule, the ultimate case of the family of flat polycyclic aromatic hydrocarbons.

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Graphene is about 200 times stronger than the strongest steel and stiff as diamond, yet at the same time is extremely flexible, even stretchable. It conducts electricity faster at room temperature than any other known material and it can convert light of any wavelength into a current.

Graphene is complicated and expensive to make in large sheets and is mostly supplied as chips or flakes. Similar to CNTs, the graphene flakes do not easily translate to application scale due to discontinuities in the macro structure. As a result, they behave more as discrete particles rather than an integrated functional network.   Graphene’s attributes lend themselves to thin film, semiconductor applications such as lightweight, thin, flexible, yet durable display screens, electric/photonics circuits and solar cells.

Miralon®

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Miralon® is continuous interconnected network of extremely long carbon tubes that does not require cross-linking or use of binders. Miralon is produced as sheets, yarn, and dispersed products. It is on the scale of millimeters (1mm-10mm) versus micrometers and classified by the EPA as an article, not a particle, which makes for safe handling. Miralon exploits many of the remarkable properties of individual CNTs spanning the electrical, mechanical, and thermal domains successfully at application scale.

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Miralon’s ultra-light weight and multi-functional macro structures can enhance or replace incumbent forms made of metal (copper, aluminum, and other conductive and/or structural metals), carbon fiber, polymer composites, fiberglass and/or advanced ceramics.

Electrically, Miralon provides excellent electro-magnetic interference (EMI) shielding in the GHz range. It also disperses well in resins and polymers enabling conductivity enhancement at very low loadings (a fraction of a percent) for applications such as electro-static discharge (ESD).     

Mechanically, Miralon demonstrates excellent stiffness for applications such as honeycomb core structures while also providing superior mechanical damping and shock protection. Synergistic interaction with aromatic-based resin systems give enhanced mechanical and electrical performance. The pliability of the material equals superior flex life, even in cryogenic environments.

Thermally, Miralon radiates long-wavelength infrared (LWIR) when electrically powered for use in heating applications. It also exhibits high thermal conductivity in the XY-direction compared to the Z-direction yielding good heat shielding and thermal spreading performance. And, like its carbon counterparts, it has a near zero coefficient of thermal expansion (CTE).

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Collectively, Miralon’s network effect of mechanical, thermal and electrical properties enables new multifunctional smart materials. For example, a 0.5% loading of Miralon into a lithium ion battery anode can dramatically increase the specific energy of a battery, halve the recharge time through increased thermal conductivity and improve overall battery ease of construction and safety through its mechanical properties.

Summary - How do CNTs, graphene and Miralon compare at the application level?

This table highlights some of the key differentiators between the three materials. 

Traditional CNTs

Graphene

Miralon®

  • Single, Hexagonal Tubes nanometer scale tubes.
  • Supplied in powder form.
  • Largely used as additive

 

  • Single atomic layer carbon crystal flakes
  • 2 D structure with strength and conductivity along the plane
  • Primarily used in semiconductor, thin film applications
  • Continuous, internetworked product format of large scale tube length (1-10 mm versus micrometer)
  • Three dimensional structure
  • Mechanical, electrical and thermal properties at application level
  • Highly effective at low concentrations

 At the end of the day, it is the deployment of the material into an application that counts.   Nanocomp has over a decade of experience integrating our tapes, sheets, yarns and dispersions into literally hundreds of applications. We welcome the conversation about application specific performance and material comparisons. 

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