Fraunhofer LBFs and PINFAs research activities on the recycling of plastics containing halogen free flame retardants

Recycling is an important issue with regard to the sustainable use of our limited resources. Only a few materials can theoretically be as easily recycled as plastics. Due to the use of different additives and specialized production processes, depending on the needs of the end application, recycling of plastics has become more and more complex. Flame retardants are a good example for additives which have to be used for different long-time applications. Due to different known advantages, halogen-free products are the flame retardants of choice.

With regard to the recyclability of flame retardant plastics after their „end-of-life“, it is of high importance to understand the influence of flame retardants on recycling. With this knowledge the development of new compatible flame retardants can be endeavored. For a better understanding, Fraunhofer LBF in Darmstadt, Germany, started a perennial project on this topic in October 2015. For the first time the recyclability of halogen free flame retardants plastics is investigated to find ways to recycle these materials and optimize the resulting polymers. At the same time this project adds a value to the sociopolitical topic of sustainable use of resources.

This project is supported by the industrial combined research support of AiF (“Arbeitsgemeinschaft industrieller Forschungsvereinigungen”, here “Forschungsgesellschaft Kunststoffe e.V.”, and the members of pinfa ( This project will bring different benefits for producers of flame retardant plastics: For them it will be possible to use some of their production waste containing non-halogenated flame retardants and thus to save costs. On the one hand, the new findings will help to increase the quality of products with high safety requirements. Possible risks due to degradation of the flame retardants will be discovered and can be compensated. On the other hand, there will be competitive advantages for the companies in using this for marketing and to build new products on this basis. For realizing this, often used commercial available systems containing non-halogenated flame retardants are in focus, including systems from the companies Clariant, Nabaltec, Budenheim, Adeka and BASF. The results have shown a consistent, non-reduced flame retardant performance after recycling.

Furthermore, repeated processing can increase the homogeneity of dispersal of the flame retardants, resulting in an increased flame retardant performance. The new findings are regularly presented at the „Arbeitskreis Flammschutz“, a meeting of “Forschungsgesellschaft Kunststoffe FGK”. In addition, new results will be presented by Dr. Elke Metsch-Zilligen at the „Fire Resistance in Plastics“ organized by AMI, in December 2017.

All pictures with courtesy of Fraunhofer LBF, Darmstadt