Fraunhofer LBF and BAM develop faster procedure for flame-retardant plastics

Scientists from Fraunhofer LBF and BAM have cooperated for the Rapid Development of Flame Retarded Thermoplastic Polyurethane projects, which aims to achieve an optimum combination of flame retardancy, processability, and mechanical properties in TPU’s.

With the ‘Combined Compounding/High Throughput Screening’ (CC/HTS) system, the researchers sought to achieve a meaningful characterisation of the produced flame-retardant TPU formulations.

The compound development was then significantly accelerated and, at the same time, made more resource-saving.

The goal of the project was to define a specification sheet in which the material properties to be obtained were determined, with a focus on mechanical parameters, which were selected by the addition of flame retardants so that the influence on the mechanical parameters would be changed as little as possible.

The rapid mass calorimeter was tested as a rapid method of fire behaviour analysis and all results were compared in detail with the corresponding measurements in the cone calorimeter.

The accompanying investigation involved pyrolysis using thermoanalytical methods, such as thermogravimetric analysis coupled with the Fourier-transform infrared spectrometer, pyrolysis gas analysis, and pyrolysis gas chromatography with mass spectrometry coupling.

It was shown that the rapid mass calorimeter is suitable to evaluate the achieved flame retardance of any flame retardant TPU.

The different TPU types displayed on few, albeit significant differences, in the mass loss of the individual decomposition stages of pyrolysis and in the mechanics.

Some formulations with nitrogen-based flame retardants showed mechanics in the pure material area, but some proved to be surprisingly similar in terms of fire behaviour and flame retardancy.

The knowledge gained can now be used directly by companies in the development of flame retardant formulations for TPU.

Furthermore, the use of halogen-free flame retardants as part of the research project demonstrated synergies between various flame retardants, simplifying the development in companies in this growth.