Improving the flame retardancy of polyamide 6 by incorporating hexachlorocyclotriphosphazene modified MWNT |
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Authors: | Jun Sun Xiaoyu Gu Sheng Zhang Mathieu Coquelle Serge Bourbigot Sophie Duquesne Mathilde Casetta |
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Institution: | 1. Key Laboratory of Carbon Fiber and Functional Polymers (Beijing University of Chemical Technology, Ministry of Education), , Beijing, 100029 China;2. ENSCL, ISP‐UMET, , F‐59652 Villeneuve d'Ascq, France |
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Abstract: | A nitrogen‐, phosphorus‐ and chlorine‐containing flame retardant, hexachlorocyclotriphosphazene (HCTP), has been covalently grafted onto the surface of multi‐wall carbon nanotubes (MWNT) to obtain MWNT‐HCTP. Polyamide 6 (PA6)/MWNT composites were then prepared via melt compounding. The flammability of PA6/MWNT composite was characterized by cone calorimetry, limiting oxygen index (LOI) and UL‐94 tests. The results showed that peak heat release rate of samples containing 3 wt% MWNT‐HCTP was only 460 kW/m2, which decreased by 35.2% compared with that of a neat PA6 sample. The LOI value was increased from 22.7% to 26.5%, and UL‐94 test performance was also significantly improved by the presence of MWNT‐HCTP. Scanning electron microscope (SEM) and optical microscope analysis showed that modified MWNT had a better dispersion and compatibility in PA6 than unmodified MWNT. The composition of residue chars and volatile products was investigated by SEM/energy dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric‐FTIR, respectively. It was proposed that grafted HCTP was mainly functioned in the condensed phase, where P, N can synergistically promote char formation and Cl element can catch free radicals to terminate the chain reaction during combustion of the PA6 composite. Copyright © 2014 John Wiley & Sons, Ltd. |
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Keywords: | multi‐wall carbon nanotubes polyamide 6 surface modification hexachlorocyclotriphosphazene flame retardancy |
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