(Source: Fraunhofer LBF)
In the event of a fire, carbon fiber reinforced plastics (CFRP) used as lightweight construction materials can become critical, as respirable fiber fragments can form which are suspected of causing cancer. In a research project, the Fraunhofer Institute for Structural Durability and System Reliability LBF, Darmstadt/Germany, together with the Wehrwissenschaftliches Institut für Werk- und Betriebsstoffe WIWeB, Erdingen/Germany, succeeded in reducing this potential hazard. For this purpose, novel flame retardants were developed that offer efficient flame protection and do not allow fibers with critical dimensions to form within realistic fire times.
The research project focused particularly on carbon fiber-reinforced epoxy resins, which are used as lightweight construction materials with optimized mechanical properties in vehicle, aircraft and ship building. The novel tailor-made flame retardants based on phosphorus polyacrylamides have several advantages. The polymeric structure prevents leaching, there is a strong plasticizer effect and it has less negative impact on thermal stability or mechanical properties.
Phosphorus flame retardants are considered harmless and release fewer toxic gases during combustion than e.g. halogen flame retardants. Thanks to the modular principle, in which initial materials and process control can be selected during synthesis, the flame-retardant mechanism and material properties can be customized.