Theo Dingemans began working on high performance polymers as a graduate student at UNC-Chapel Hill. After completing his degree, Dingemans began work at the advanced materials and processing branch at NASA- Langley—one of the world leading institutes doing work in composites. In 2003, Dingemans returned to his native Netherlands, where he teaches at TU Delft as a professor of Aerospace and Engineering, working on polymers and composites.
What is your current research focus at TU Delft?
We try to help find solutions. We’re trying to provide the aerospace industry with new polymer-based materials to use, which can either be resins or fibers. We also research new chemistry make-ups as well as try to fix existing polymer related problems within composites.
As a department, we come up with new concepts such as multifunctional polymers, which are like a structural polymer uses in composites but have an extra function such as a photovoltaic, energy storage capacity, sensor, transistor or self-healing mechanism.
What primary applications would the aerospace industry like improved?
There are major issues, such as the poor compressive behaviors of the fibers. Composites do really well under tension in their current design, but under bending or compression, they fail miserably. We are trying to fix the characteristics that cause those problems and work on resin materials that incorporate a higher end-use temperature, more toughness and better solvent resistivity.
Where are these flaws an issue?
If you design an aircraft, money isn’t much of an issue, because the materials aspect is minimal compared to hardware. On a satellite for example, manufacturers can afford to use the best polymers that are out there. When you look at an airplane, however, price becomes an issue. One of the biggest problems right now with airplanes is skydrol resistivity, which is a hydraulic fluid that most components—especially the polymer component—doesn’t like. After prolonged exposure to skydrol, the polymer swells and becomes soft. A famous example of this is the wet wing design where people decided to make an all-composite wing out of polymer fiber reinforced composites. They dumped the fuel in there, and it was an automatic fuel tank. But that didn’t really work because the polymer was swelling and they ended up building a fuel tank in the end.
Are there other big flaws?
Some of the biggest problems the aerospace industry currently faces are solvent resistivity, toughness and fiber-to-resin interface (resin adhesion to fiber). All these problems translate back to design rules. To give you an idea of how complex these problems are, the current tests used to certify the composite parts aren’t even really given the right information.