Researchers at the Fraunhofer Institute for Chemical Technology ICT in Munich, Germany, have developed a way to make safer composites for automobiles. Called thermoplastic resin-transfer molding (T-RTM), the technique builds materials which buckle on impact.
Automakers typically build such components from thermosets — cross-linked polymers cured using heat or heat and pressure. Researchers say the new technique is simple and quick and thus better suited to mass production, unlike methods needed for thermosets. This could make it possible for a factory to manufacture up to 100,000 parts a year. T-RTM composites also don’t delaminate and splinter in collisions, making them safer. And T-RTM lets researchers select curing temperatures to minimize processing times. Further, at the end of their useful life, T-RTM parts can be shredded, melted down, and the material reused in high-quality parts.
“The cycle time to make thermoplastic components is around 5 minutes,” says Dieter Gittel, a project manager at ICT. “Comparable thermoset components frequently take more than 20 minutes.”
The composite is formed in a single step. “We insert preheated carbon or glass fibers into a temperature-controlled mold so that the fibers align with anticipated stress,” says Gittel. Next, the activated monomer melt is injected into the mold. The melt contains a catalyst and activator — the chemicals necessary for polymerization.
In a recent project, ICT engineers replaced the aluminum trunk liner in the Porsche Carrera 4 with one made using T-RTM. Not only has the new liner improved the crash behavior of the vehicle’s overall structure, it weighs 50% less than the original part.