Resins take the heat in fuel cells
New thermoset resin systems from Huntsman Advanced Materials (Basel, Switzerland) meet the most stringent requirements for graphite-based composite bipolar plates used in fuel cells for automotive and stationary power applications.
For the automotive sector, Huntsman has developed a benzoxazine resin suitable for high temperature PEM fuel cells. The resin, which operates at a continuous temperature of 120ºC, has a phenolic-like backbone that gives it very good flame-retardant properties together with excellent glass-transition temperatures and mechanical properties. In particular, there is a very high modulus, low water absorption, and near-zero shrinkage, as well as good electrical properties.
For stationary power and back-up power applications, a bismaleimide resin has been developed for fuel cells operating at temperatures of up to 180ºC in concentrated phosphoric acid. The resin is flame resistant and provides the fuel cells with excellent thermal and electrical conductivity, a low ionic content, and can be applied in continuous high-volume manufacturing processes using conventional prepregging techniques.
The resins have been developed in conjunction with GrafTech International (Parma, OH) as part of a U.S. Dept. of Energy-sponsored program. The cells have already undergone extensive testing and are expected to be available commercially soon.
Also from Huntsman: Thermoset resins are normally considered rigid, but an epoxy offering from this firm relegates this assumption to the annals with its elastomeric attributes.
Araldite HFC has similar material characteristics to elastomers—excellent impact, abrasion, and tear resistance with good elongation and tensile resistance—but it is very different in terms of material and production time costs.
Only a few consumable materials are required, according to the supplier—resin and fiber—and, most important, just a single shell mold is required for component production. As opposed to elastomers, where it is difficult to incorporate fabric reinforcement, and the processing is complex and expensive, the processing of low-viscosity Araldite Highly Flexible Composite is reportedly simple.
“Traditional systems are very hard and rigid, but our new system imparts high flexibility and impact strength,” says the Asia Pacific advanced materials technology director at Huntsman. “This new concept will bring new opportunities in areas such as furniture, automotive, and ski boots.”
