Rapid mass calorimeter as a high-throughput screening method for the development of flame-retarded TPU. (October 2018) - Sut, Aleksandra
Abstract: The rapid mass calorimeter (RMC) was used as a screening tool based on accelerated fire testing to assess flame-retarded thermoplastic polyurethane (TPU). The reliability of RMC results was proven with the cone calorimeter as reference fire test. The influence of melamine cyanurate (MC) concentration on the fire performance of TPU was investigated, along with some flame-retardant combinations such as MC with aluminium diethylphosphinate (AlPi), aluminium trihydrate (ATH), and melamine polyphosphate (MPP). The two-stage burning behaviour of TPU was investigated in detail; the first stage corresponds mainly to the hard segments' decomposition and has a much lower effective heat of combustion (EHC) than the second stage, in which mainly the soft segments decompose and an intensive liquid pool fire is observed in the cone calorimeter set-up. In addition to fire testing with the cone calorimeter, RMC, and UL 94 flammability tests, the decomposition of the materials was investigated using thermogravimetric analysis coupled with infrared spectrometry (TG–FTIR). TPU/MC/AlPi shows the most promising results, achieving V-0 classification in UL 94 and reducing the extreme peak heat release rate (PHRR) of the liquid pool fire from 3154 kW/m 2 to 635 kW/m 2 . Using MC/AlPi/MPP enhances the latter PHRR reduction further. The decomposition products identified in the gas phase via TG–FTIR reveal specific MC–AlPi–MPP interactions, as they differ from products seen in systems with MC/AlPi or MC/MPP. Correlations between RMC and cone calorimeter results were examined and presented in the final part of the paper. Several characteristics correlate strongly, pointing out that RMC is a reliable high-throughput fire testing method to screen multicomponent flame-retardant solutions in TPU. Highlights: Multi-methodical approach develops flame retarded TPU with focus on high-throughput screening rapid mass calorimeter (RMC). A systematic row of multicomponent flame retarded TPU was investigated to identify the synergistic interactions. The reliability of RMC was proven by correlations with the cone calorimeter and the Pearson correlation coefficient R was between 0.87 and 0.98 for selected parameters. This comprehensive study allowed distinguishing promising materials which reached UL-94 classification V-0 and the peak heat release rate (PHRR) reduction by 80% in some cases.