Flame retarding mechanism of Polyamide 6 with phosphorus‐nitrogen flame retardant and DOPO derivatives

Abstract

A novel flame-retardant composite was prepared by introducing a phosphorus-nitrogen flame retardant and DOPO-SiO 2 into PA6. DOPO-SiO 2 was synthesized successfully in a one-step process. PA6/OP1314/DOPO-SiO 2 achieved a UL 94 V-0 rating with an LOI value of 31%. The maximum mass loss rate of decomposition decreased significantly and char residue increased to 11.6 wt % compared with that of pure PA6. The compacted and dense char was formed due to the combination of the P-N flame retardant and DOPOSiO 2 . The complex viscosity of PA6/OP1314/DOPO-SiO 2 increased considerably which tend to prevent the dripping phenomenon. The flame-retardant mechanism of PA6/OP1314/DOPO-SiO 2 was also investigated by Fourier transform infrared spectroscopy FTIR at different temperatures and the pyrolysis products were investigated by pyrolysis gas chromatography/ mass spectrum (Py-GC/MS). It was assumed that DOPO-SiO 2 and the hypophosphite of OP1314 possess excellent flame retardancy during the gaseous phase. Meanwhile, melamine and phosphate reacted with the pyrolytic products of PA6 to protect the matrix during the condensed phase. V C 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42932.

Heat propagation in thermally conductive polymers of PA6 and hexagonal boron nitride

“…The maximum mass loss rate is similar with 2.05%/°C. This has already be shown in the literature . At 650°C, a residue of 3.44% remained (Figure ).…”

“…However, only introducing the FR cannot eliminate the melt dripping behavior. Further information and preliminary work can be found elsewhere . The hBN is platelet‐shaped with an average particle size of approximately 15 μm.…”

Effect of graphite on the flame retardancy and thermal conductivity of P‐N flame retarding PA6

“…The flame of the spline went out after nearly 8.2 s during the second test. As our previous research showed, OP1314 can release diethylphosphinic acid acting as the chain‐terminating agent during the decomposition process . Thus, the sample with OP1314 could self‐extinguish in a short time, which resulted in the increasing of the LOI value.…”

“…With the LOI value of 23%, neat PA6 was easy to burn in air with continuous flaming drippings and without self‐extinguishing. Exolit OP1314 was a universal non‐halogen flame‐retardant for polyamides, with the addition of 12 wt % OP1314 added, the LOI value has a significant increase to 28.0% and the flame extinguished in 2.5 s without drippings after the first combustion test. Unfortunately, some burning melt‐droplets dripped and ignited the absorbent cotton under the spline.…”

“…Wang studied the synergistic effects of metal salt of Novolac (NA‐Fe 2 O 3 ) with a P‐N FR on the flame retardancy of PA6 and by introducing 12 wt % P‐N FR/18 wt % NA‐Fe 2 O 3 , the melt dripping of flame‐retardant PA6 disappeared and reached the UL94 V‐0 rating . On the whole, synergistic agents can effectively reduce the additive amount of FRs and thermal conductive fillers, while increase the flame‐retardant properties and properly thermal conductive properties.…”