The 19th edition of FRPM (Fire Retardant Polymeric Materials Conference) www.frpm-23.org was hosted by Empa, Switzerland, 26-29 June 2023. This is one of the world’s biggest flame retardant conference, with nearly 250 participants, 69 oral presentations and 70 posters. 185 of the participants were from Europe. 65% were from academia, 35% from industry and other stakeholders. Conference papers will be published in in the Journal of Material Science and Technology or the Journal of Polymer Degradation & Stability. pinfa members were actively present (BASF, Clariant, DTNW, ICL, Lanxess, Sabic, Schneider Electric) and pinfa both sponsored the Conference and specifically offered (for the first time at FRPM) Awards for young researcher presentations.
The 20th FRPM Conference will take place 6th – 9th June 2025 in Madrid, hosted by IMDEA.
As well as presentations on pure and applied flame retardant chemistry research, applications, fire safety trends and regulations, participants enjoyed glorious Swiss weather, a superb gala dinner high above Zurich (sponsored by Clariant), a visit to Empa’s experimental green construction building NEST, alpenhorn and yodelling, and many opportunities for networking and discussions.
Most presentations showed laboratory research into possible new flame retardant chemicals or materials (nearly 50 presentations, of which around one third on bio-based chemicals or materials, several on vitrimers, fire behaviour or chemistry modelling …), around fifteen presentations addressed industrial flame retardant applications (more than a third on battery fire safety) and nearly ten presentations discussed policy, regulation and recycling. A number of presentations from China, or coming from cooperation between European and Chinese research organisations showed the extensive range of flame retardant chemistry research ongoing in China. Many of the research presentations of new FR chemistries showed improved LOI (Limiting Oxygen Index) or reduced Heat Release at the lab scale, but did not demonstrate applied industry validation testing (e.g. UL 94).
Of the 140 oral presentations and posters, nearly all of those on new flame retardant technologies or applications centred on PIN FR chemistries (most on phosphorus chemistries, with also nitrogen, sulphur, silica, metal synergists and other inorganics). Presentations on recycling and on regulation considered halogenated flame retardants, because of their legacy presence in today’s end-of-life products. Certain brominated FRs pose increasing obstacles to recycling because they are POPs and increasingly tight regulations mean that traces in reprocessed polymers can exclude these from recycling. The conference also noted the EU targeting of brominated FRs as priorities for regulation (ECHA Roadmap).
What were the leading themes at FRPM 2023?
New flame retardant chemicals
- especially based on phosphorus PIN FR chemistries: new organo-phosphorus chemicals, often derived from DOPO, reactive PIN phosphorus FRs
- sulphur- and/or nitrogen-based PIN chemicals, as synergists for phosphorus PIN FRs
- ionic liquids to deliver synergist metals (catalysis of char formation)
- inorganic boron and metal synergists, silicon minerals: which can glassify phosphorus chars, so improving fire resistance
Research into bio-based or waste-derived flame retardants
- experimental synthesis and testing of new bio-derived chemicals: presentations showed interesting possible future routes, but without yet information on industrial feasibility: supply, quality consistency, cost.
- research testing of different waste / secondary materials as PIN FR synergists: flue gas sulphur-removal gypsum, power plant fly ash …
Sustainability, chemical safety and recycling
- recycling: use of PIN FRs to ensure fire-safety of recycled materials (necessary for their use in many applications), recycling of flame retarded polymers.
- smoke toxicity in fires, which is often the main cause of deaths and injuries, either directly or by preventing escape (incapacitation, visibility), for example related to nitrogen-containing polymers (cyanide). PIN FRs acting in the solid phase reduce smoke (char barrier layer) but gas phase FR action, whilst being effective in quenching flames, can increase smoke: how to balance these effects?
- water-based FR synthesis or application, e.g. to textiles.
- the question was raised of how to prevent burning-dripping (essential to pass UL 94 V-0 and to prevent fire spread in real life) whilst avoiding the currently-used PFAS anti-drip additive PTFE. But no research presented addressed this.
- both industry and the European Commission (ECHA) underlined the aim to move to Safe and Sustainable by Design chemicals (SSbD), but the majority of presentations proposing new FR chemicals did not consider their compatibility with recycling, nor their possible toxicity and environmental safety.
FR trends, new applications
- reactive and polymeric phosphorus flame retardants, including for example replacing part of epoxy by a P-epoxy
- fire safety challenges of batteries, including battery fire gas toxicity
- flame retardants for polymers for 3D-printing
- new phosphorus-nitrogen PIN FR solutions for textiles
- computer modelling and AI to design new FR chemistries and model toxicity, fire performance
Mechanisms of flame retardants
- combining solid phase (char) and gas phase (radicals) fire performance effects of phosphorus FRs.
- new PIN radical generators for gas-phase fire quenching effects, e.g. amines or silanes.
- link between oxidation state of phosphorus in PIN FRs and fire performance effect: high oxidation state – char generation / low oxidation state – gas phase action.
- synergies between phosphorus PIN FRs and sulphur or silicon compounds.
- synergists to improve char production and structure.
- links between gas-phase action of FRs (fire quenching), smoke emission and smoke toxicity: carbon monoxide, smaller smoke particles, aldehydes, hydrogen cyanamide (nitrogen containing compounds).
- the widespread use of the cone calorimeter for materials fire testing is questioned as not representing real fire conditions. Oxygen supply is generally inadequate in real fires, resulting in smoke toxicity which is not shown with the cone calorimeter, which is well ventilated.
Conference conclusions
The lead organiser of this FRPM Conference, Sabyasachi Gaan, Empa, concluded the conference by thanking the organisation team and the conference sponsors, and summarised the themes he saw as emerging at this 2023 19th edition of FRPM:
- sustainability, environment and recycling
- new developments in flame retardant chemistries and synergies
- modelling of fire behaviour and testing
- applications in transport, construction, textiles
- new developments in e-mobility and batteries, 3D-printing