In this interview, Felix Goldmann and Reid Averill from Evonik ROHACELL® talk about the benefits of ROHACELL® EC conductive foam, and applications in aerospace stealth and electronic devices.
To start with, can you give us a brief introduction to ROHACELL® products and tell us which industries use them?
For more than 40 years, Evonik's ROHACELL® structural foam has been used in the aerospace and automotive industries, as well as in sports equipment, shipbuilding, medical technology, and other markets to create lightweight composite components.
ROHACELL® closed-cell foam, which is based on polymethacrylimide (PMI) chemistry, is typically used as a core between FRP facings. The mechanical properties are impressive for a low density foam product. Special properties have been engineered for certain applications, and for many grades these properties can be further enhanced through heat treatment (HT) of the foam.
When it comes to processing, the heat distortion temperature and creep compression strength of ROHACELL® are superior to those of any other rigid, structural foam.
Do any of your foams offer additional advantages that go beyond structural support?
Yes, ROHACELL® products have gained increased usage in the growing composites industry, where mass reduction and mechanical strength are critical. Additionally, we offer specialty products with unique benefits.
Our closed-cell structural foams have the potential to bring value in multiple roles. In particular, we have an electrically conductive grade marketed as "ROHACELL® EC". This product is capable of transferring loads as efficiently as our other ROHACELL® products, but what makes it most interesting is that ROHACELL® EC is also capable of absorbing electromagnetic waves and then dissipating this energy in the form of heat.
The dielectric properties of this product are truly unique in the world of structural composite materials. Even more impressive is the fact that the foam properties are homogeneous both electrically and mechanically.
Since the carbon black particle dispersion is completely uniform, the performance properties of the entire sheet are consistent throughout. Our customers tell us ROHACELL® EC is the only product of its type where they can find this high level of quality.
Which applications can benefit most from these unique dielectric properties of ROHACELL® EC?
We are seeing more and more stealth applications every year with increasing needs for dependable radar absorption capabilities. There are endless applications for unmanned systems such as UAVs and other aircraft including tactical jets and helicopters. EM shielding is definitely a growing field.
A structural conductive foam like ROHACELL® EC can bring something new to the marketplace for other industries. For example, it presents limitless possibilities for product designers in the electronics industry.
The cellular phones we all use each day require components that aid in isolation and prevention of interference from other radio frequency signals. Our ultra-lightweight material is perfectly suited for these types of applications.
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ROHACELL® EC from Evonik
What about mechanical properties, compressive creep performance and processing -- how does ROHACELL® EC differ from standard ROHACELL® product grades?
The great thing about ROHACELL EC® is that it exhibits the same thermomechanical performance as our well-known aerospace grades (WF, RIST, XT). Due to the 100% closed-cell structure of all our foams, in processing up to 180°C and 0.7 MPa, resin absorption remains controlled at the core surface.
Even at low densities, our foam offers maximum strength and stiffness to a finished part – exactly the same performance you get from all ROHACELL® products. And of course it can be easily shaped to precision-tight tolerances to fit geometries that a design may require.
What separates ROHACELL® EC from other foam core materials on the market today?
There are numerous EM absorbing product solutions on the market today, including non-structural foams. However, we are not aware of another structural foam core that offers a combination of superior mechanical properties and electrical performance, plus efficient processing capabilities as an all-in-one core solution.
This makes ROHACELL® EC a truly unique material that can provide impressive EM absorption performance, without sacrificing any lightweight design potential.
How do you see this market developing over the coming years?
There is a growing need for more diverse material offerings in the radar absorbing materials category. Every day, our interactions with industry designers are revealing that ROHACELL® EC can provide some unique and unexpected benefits for many end products.
We are learning that aside from the growth in stealth applications, there is emerging interest coming from several industries.
Where can readers find more information about ROHACELL® foams?
Visiting our website at www.rohacell.com is a great starting point to learn more about all of our products, including ROHACELL® EC. There you’ll find downloadable literature, videos, product stories and a listing of our in-country representatives around the world where you can reach out to them directly using the phone numbers and e-mails provided.
So if you would like to talk more about any ROHACELL® product or your applications – contact us!
About Reid Averill
Reid Averill is a Technical Sales Manager for Evonik Industries ROHACELL® North America.
Reid's composites background started at the University of Mississippi where he worked in the pultrusion lab, researching pultrusion-based resin systems such polyurethane, epoxy and phenolic. Reid's love for composites led him to seeking a Master's Degree in Materials Science while doing research on the electrical properties of pultruded composites.
Upon graduation, Reid went to work for a major aerospace company building large composite structures out of ROHACELL® before joining Evonik in 2007.
About Felix Goldmann
Felix Goldmann is the Global Market Segment Manager for the Lifestyle Segment at ROHACELL®, which comprises the Electronics & Radome, Sports Equipment, and Medical application markets.
Felix studied plastics engineering at the University of Applied Sciences in Darmstadt, Germany where he acquired a Master's degree. He began his career in Evonik’s ROHACELL® application lab in 2008 before moving into a sales and marketing role.
Having held several marketing positions on the ROHACELL® team, he became responsible for the Lifestyle segment in 2013.
Evonik is aware of its product responsibility to the global community and takes reasonable care in the distribution of its products.
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