Whether you think Joel Embiid’s mask is more Iron Man or Phantom of the Opera, one thing’s for sure — it’s strong.
A collision with teammate Markelle Fultz near the end of the season sidelined the 76ers’ all-star center for three weeks with a fractured orbital bone. After missing the team’s first two playoff games, Embiid returned in dramatic fashion, sporting the protective mask that has already drawn the attention of fans and the ire of opponents.
With the team in the midst of a postseason run, the man and the mask will be put to the test over the next few weeks. To understand how the lightweight face protection gets its durability, a doctoral researcher in Drexel’s College of Engineering, explains the material science behind The Mask.
Ariana Levitt is developing conductive fibers and yarns as part of her doctoral research in the Department of Materials Science and Engineering, co-advised by College of Engineering Professor Yury Gogotsi, PhD, and Westphal College Associate Professor Genevieve Dion. Levitt’s work with conductive nanofibers could one day contribute to wearable energy storage devices that could power a “smart shirt” for real-time health monitoring of athletes. Levitt recently shed some light on the unique combination of polymer materials that give Embiid’s mask its protective properties.
Embiid’s mask is made from a special material, more commonly used in prosthetics, that combines polypropylene and embedded carbon fiber filaments. What is it about this combination that makes the mask durable and lightweight?
The mask is made from a composite material, meaning that the material consists of two parts: a matrix and a reinforcement. In this case, the carbon fibers act as the reinforcement and the polymer, polypropylene, binds the fibers together, transfers the load to the fibers, and protects the fibers from abrasion and environmental effects. Carbon fibers are fine fibers (5-10 microns in diameter) known for their extremely high strength and elasticity. Polypropylene is a thermoplastic polymer that has a low density and high toughness. Combining the properties of these two materials into one composite results in a mask that is lightweight, strong, and tough.
How is this material different than materials such as carbon-fiber or fiberglass that people are pretty familiar with? What advantages might this material have over those materials?
Since this material is a composite material — meaning that it is composed of two materials — it is unlike carbon fiber or fiberglass, which are single materials composed of one part. By combining two materials together, composite materials are designed to have very specific properties. For example, they can be made anisotropic, meaning that the material has different properties in different directions. Carbon fiber on its own is extremely strong, however, embedding these fibers into a flexible and tough matrix expands the potential applications of these fibers.
What other materials are currently in use — or being developed — that apply a similar process of treated fibers or polymer combination to produce materials with specific properties like what’s in the mask?
Fiber reinforced composite materials are becoming increasingly popular across many fields, including the automobile industry and the aerospace industry. Since these materials are light weight, they are ideal in applications where saving weight is critical (such as in airplanes). They are also commonly used in sporting goods, like tennis racquets. Other fiber-based materials used in these composites are glass fibers, which are used for insulation, and aramid fibers, which are heat resistant and can be found in firefighters’ uniforms.
Your research focuses on creating fibers that are electrically conductive and can be used to make durable energy storage devices – what are the challenges of working with fibers? What makes them an appealing component for developing advanced materials?
There are many challenges with developing conductive fibers, specifically fibers that will be used in textile applications. There are many different fiber-processing methods used to develop fibers, including melt-spinning and wet-spinning, and also various coating and plating techniques to introduce conductive materials into non-conductive fibers and yarns. Currently in our lab, we are experimenting with various coating methods. Some of the challenges we are facing include maintaining the mechanical properties (strength and flexibility) and feel of the original fiber/yarn and improving the abrasion resistance of the composite.
Highly conductive fibers and yarns are needed to bring us closer to developing truly wearable smart garments, meaning garments that are free from rigid and bulky components, like traditional wires and cables.
If we could look into the future 25 years from now, what kind of materials do you think protective devices like this might be made out of?
A new family of two-dimensional materials was developed here at Drexel in 2011, known as MXenes. MXenes are known for their extremely high conductivity and modulus (elasticity/rigidity). In our lab, we’re working on developing MXene fibers and in 25 years, we see these fibers being used in all kinds of wearable devices – from protective devices, like Embiid’s mask, to self-powered smart textiles that can monitor your heart rate and charge your smart watch.
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