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Synergistic effect of DOPO immobilized silica nanoparticles in the intumescent flame retarded polypropylene composites
Author(s) -
Dong Quanxiao,
Liu Mingming,
Ding Yanfen,
Wang Feng,
Gao Chong,
Liu Peng,
Wen Bin,
Zhang Shimin,
Yang Mingshu
Publication year - 2013
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/pat.3137
Subject(s) - intumescent , materials science , thermogravimetric analysis , polypropylene , limiting oxygen index , fire retardant , char , composite material , nanoparticle , thermal stability , rheology , chemical engineering , pyrolysis , nanotechnology , engineering
The synergistic effect of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) immobilized silica (SiO 2 ‐DOPO) nanoparticles with an intumescent flame retardant (IFR) on the flame retardancy of polypropylene (PP) was investigated by UL 94 vertical tests and limiting oxygen index (LOI) measurements. It was found that the PP/IFR composites (25 wt%) achieved the UL94 V0 grade and LOI increased to 32.1 with an incorporation of 1.0 wt% SiO 2 ‐DOPO nanoparticles. Based on thermogravimetric analysis, scanning electronic microscopy and rheological analysis, it is speculated that three factors are mainly contributed to the improvement of the flame retardancy. First, the thermal stability of PP/IFR composites was improved by incorporating SiO 2 ‐DOPO nanoparticles. Second, the presence of SiO 2 ‐DOPO nanoparticles could induce the formation of a continuous char skin layer during combustion. The compact char layer could effectively impede the transport of bubbles and heat. Third, rheological analysis indicated that SiO 2 ‐DOPO nanoparticles could increase viscosity of the PP/IFR composites, which was also benefited to increase flame retardancy. Copyright © 2013 John Wiley & Sons, Ltd.