Flame retardant research

A flame retardant is a material used for fire protection. It slows or completely prevents combustion or ignition. Research of new materials for fire protection is motivated by the need for a greener and more economical form of production. These materials are mainly used as additives in building materials. They can be used to make various protective packaging or, for example, lightweight frame structures such as the skeletons of bicycles, boats, aircraft, or other means of transport.

The research aimed to develop new flame retardants for carbon fiber-reinforced epoxy composites. These new compounds are based on phosphazenes or other useful derivatives of phosphate-based compounds. The phosphorus-based compounds hexachlorocyclotriphosphazene and phosphoric acid oxychloride are advantageous routes for chemical preparation from the EU legislation and policy perspective. The selected phosphorus derivatives are, in fact, non-hazardous, and once the preparation and purification conditions have been optimized, they are simple synthetic processes with the production of stable products.

The principal investigator of the project is the company SYNPO, based in Pardubice. The Applied Plasmochemistry research group has been cooperating with SYNPO for a long time. In previous joint projects, they researched, developed, and produced new hybrid composite materials, functional layers, and plasma-modified surfaces. Other collaborating organizations on the flame retardant project include the Slovak Academy of Sciences (Polymer Institute, Slovak Academy of Sciences PISAS) or the Institute for Mechanics of Materials, University of Latvia, Riga, Latvia.

The most important aspect of the research was the functionality of the newly produced flame retardant composites. "Our composites work quite well. The retardant causes a shortening of the flare-up time of the material. The combustion still blazes, but for example, at temperatures around 250°C and no longer around 800°C. The whole burning process takes less time with the addition of the additive. There is also a slower loss of the material. The material appears to swell, further limiting the oxygen supply to the combustion source and thus limiting the spread of the fire itself within the material. Furthermore, there is less oxygen consumption from the surroundings and less smoke formation," comments Dr. Pijáková.

Epoxy additives were prepared at Masaryk University. The final preparation of the composites was carried out directly at SYNPO company. Dr. Pijáková and Dr. Prokeš analyzed both the prepared additives and the final products using various methods: NMR, FTIR, EDX, SEM and MS. "Working with phosphazenes is not easy. They are susceptible to temperature changes and water vapor during preparation. It is, therefore, necessary to have clean and dry chemicals and chemical glassware. At the same time, samples are difficult to analyze if mixtures of derivatives are formed. In some syntheses, liquid nitrogen at -40 °C cools exothermic reactions. I have also used liquid ammonia at -60 °C for synthesis and product purification," adds Dr. Pijáková.

The utility model and the functional sample are the main results of this project. SYNPO can now produce the material industrially according to the needs of its customers. The scientists have presented their results at several chemical conferences and are currently working on further follow-up projects.