Effects of melamine polyphosphate on explosion characteristics and thermal pyrolysis behavior of polyamide 66 dust

Polyamide 66 (PA66) is widely used in the polymer market and there is a risk of dust explosion during processing and manufacturing. In this study, the explosion hazard of PA66 dust and the inerting effect of melamine poly-phosphate (MPP) in PA66 dust were evaluated by testing the explosion characteristic parameters. The results showed that the maximum explosion pressure (P-max), minimum ignition energy (MIE), and minimum ignition temperature (MIT) of PA66 dust were 5.6 bar, 48 mJ and 430 degrees C, respectively. No explosion occurred after the addition MPP reached 50 wt%. Moreover, the thermal pyrolysis behavior of the mixed dust was revealed by thermogravimetric analysis (TGA) and TG coupled with FTIR (TG-FTIR) analysis. The results showed that C3H6, produced during the pyrolysis of PA66, was the main combustible gas. However, the addition of MPP promoted the CO2 production of PA66 and consumed a large amount of free radicals. It was also found that the polyphosphate from MPP decomposition chemically reacted with PA66, which reduced the decomposition temperature of PA66 and produced an extended carbon layer. These results are an important reference value for the prevention and control of dust explosions in polyamide.

Automated summary

Polyamide 66 (PA66) poses a risk of dust explosion during processing and manufacturing, but the addition of melamine poly-phosphate (MPP) can effectively reduce this hazard. The values of maximum explosion pressure, minimum ignition energy, and minimum ignition temperature of PA66 dust were significantly reduced after adding MPP. Furthermore, the thermal pyrolysis behavior of PA66 dust was altered by the addition of MPP, affecting the production of combustible gases and the formation of carbon layer.