Halogen-containing flame retardants are not preferred for environmental reasons. Herein, a halogen-free intumescent flame-retardant ethylene-vinyl acetate copolymer (EVA/IFR) system containing organic montmorillonite (OMMT) and graphene nanosheets (GNSs) is fabricated with well dispersion structure, enhanced thermal-oxidative resistance at high temperature. Interestingly, the amount of residual chars from thermogravimetric analysis is increased to 12.7 wt % at 700 8C, the EVA/IFR composite containing both OMMT and GNSs exhibits the best flame retardancy with the lowest peak heat release rate value of 529.58 kW m 22 , and the highest limited oxygen index value of 24.8%. The excellent flame retardancy is attributed to the formation of complete and compact protective char layer. Furthermore, the decreases of the mechanical properties caused by the addition of IFR are relieved and a high volume resistivity is maintained when combining OMMT and GNSs in the EVA/IFR system together. V C 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46361.
A novel flame retardant (FR) containing phosphorus and calixarene structures was synthesized, and the FR combined with ammonium polyphosphate (APP) was then incorporated into polystyrene (PS). The flame retardancy and thermal stability of the flame retardant composites were investigated. The limiting oxygen index can reach 21.0% when the mass ratio of FR/APP was 3:2. Char residues at 650°C in an air atmosphere increased from 2.2% to 21.5% notably when FR/APP was incorporated into PS matrix, indicating an improvement of thermo‐oxidation resistance. Compared to the virgin PS and FR/PS composites, the peak heat release rate of FR/APP/PS composites is reduced to 259.87 kW/m2 (PS8), indicating synergistic flame retardant effects between FR and APP. Generally, stable char layer of FR/APP/PS is responsible for the improved flame retardant properties, which not only effectively prevented the release of combustion gases but also protect the interior substrate from oxygen and heat permeation.
Graphene aerogel (GA) with nano-porous structure was assembled through the formation of physical cross-links between graphene sheets by a facile sol-gel method and supercritical CO 2 drying process. Then hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) was added and trapped in the nano-porous three-dimensional networks of GA to obtain a novel GA/RDX nanostructured energetic composite. The composition, morphology and structure of the obtained GA/RDX nanostructured energetic composite were characterized by elemental analysis, scanning electron microscopy, nitrogen sorption tests and X-ray diffraction. Moreover, the thermal decomposition characteristic was investigated by thermogravimetry and differential scanning calorimetry. The results showed that GA could be a perfect aerogel matrix for the fabrication of GA/RDX nanostructured energetic composite due to its unique nano-porous structure and attributes. It was also demonstrated that RDX homogeneously disperses in the asprepared GA/RDX nanostructured energetic composite at nanometric scale. GA showed promising catalytic effects for the thermal decomposition of RDX. After incorporating with GA, the decomposition of RDX was obviously accelerated.
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