The synergistic flame‐retardant effect of O‐MMT on the intumescent flame‐retardant PP/CA/APP systems

The flame retardancy of a novel intumescent flame‐retardant polypropylene (IFR‐PP) system, which was composed of a charring agent (CA), ammonium polyphosphate (APP), and polypropylene (PP), could be enhanced significantly by adding a small amount (1.0 wt%) of an organic montmorillonite (O‐MMT). The synergistic flame‐retardant effect was studied systematically. The thermal stability and combustion behavior of the flame‐retarded PP were also investigated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), vertical burning test (UL‐94), scanning electronic microscopy (SEM), and cone calorimeter test (CCT). TGA results demonstrated that the onset decomposition temperatures of IFR‐PP samples, with or without O‐MMT, were higher than that of neat PP. Compared with IFR‐PP, the LOI value of IFR‐PP containing 1.0 wt% O‐MMT was increased from 30.8 to 33.0, and the UL‐94 rating was also enhanced to V‐0 from V‐1 when the total loading of flame retardant was the same. The cone calorimeter results showed that the IFR‐PP with 1.0 wt% of O‐MMT had the lowest heat release rate (HRR), total heat release (THR), total smoke production (TSP), CO production (COP), CO₂ production (CO₂P), and mass loss (ML) of all the studied IFR‐PP samples, with or without O‐MMT. All these results indicated that O‐MMT had a significantly synergistic effect on the flame‐retardancy of IFR‐PP at a low content of O‐MMT. Copyright © 2009 John Wiley & Sons, Ltd.     

Flame retardancy and thermal degradation of intumescent flame retardant polypropylene material

The flame retardancy and thermal degradation properties of polypropylene (PP) containing intumescent flame retardant additives, i.e. melamine pyrophosphate (MPyP) and charring‐foaming agent (CFA) were characterized by limiting oxygen index (LOI), UL 94, cone calorimeter, microscale combustion calorimetry, and thermogravimetric analysis (TGA). It has been found that the PP material containing only MPyP does not show good flame retardancy even at 30% additive level. Compared with the PP/MPyP binary system, the LOI values of the PP/MPyP/CFA ternary materials at the same additive loading are all increased, and UL 94 rating is raised to V‐0 from no rating (PP/MPyP). The cone calorimeter results show that the heat release rate and mass loss rate of some ternary materials decrease in comparison with the binary material. The microscale combustion calorimetry results indicate that the sample containing 22.5 wt% MPyP and 7.5 wt% CFA has the lowest heat release rate among all samples. The TGA results show that the thermal stability of the materials increases with the addition of MPyP, while decreases with the addition of CFA. Copyright © 2009 John Wiley & Sons, Ltd.     

AN EVA/UNMODIFIED NANO-MAGNESIUM HYDROXIDE/SILICONE RUBBER NANOCOMPOSITE WITH SYNERGISTIC FLAME RETARDANCY

A novel EVA/unmodified nano-magnesium hydroxide(NMH)/silicone rubber ternary nanocomposite was prepared by using a special compound flame retardant of NMH and silicone rubber(CFR).The flammability of the ternary composite was studied by cone calorimeter test(CCT).Synergistic effect on flame retardancy was found between silicone rubber and NMH.EVA/CFR ternary nanocomposite showed the lowest peak heat release rate(PHRR)and mass loss rate (MLR)among the samples of virgin EVA,EVA composites.The synergistic flame retardancy of silicone rubber and NMH in EVA system is attributed to the enhanced char layers in the condensed phase that prevents the heat and mass transfer in the fire.     

Synergistic effect of boron containing substances on flame retardancy and thermal stability of intumescent polypropylene composites

The synergistic effect of four different boron containing substances, zinc borate (ZnB), borophosphate (BPO₄), boron silicon containing preceramic oligomer (BSi) and lanthanum borate (LaB), were studied to improve the flame retardancy of a polypropylene (PP) intumescent system composed of ammonium polyphosphate (APP) and pentaerythritol (PER). The flame retardancy of PP composites was investigated by limiting oxygen index (LOI), UL-94 standard, thermogravimetric analysis (TGA) and cone calorimeter tests. The addition of 20 wt% intumescent flame retardant (IFR) improves the flame retardancy by increasing the char formation. According to LOI and UL-94 test, boron compounds show their highest synergistic effect at 1 wt% loading. BPO₄ containing composite shows the highest LOI (30), lowest maximum heat release rate (HRR) and lowest total heat release rate (THR) value. Although the char yield increases as the amount of boron compounds increases, the flame retarding effect decreases. Cone calorimeter and TGA data indicate that the boron compounds are likely to show their synergistic effect by reinforcing the integrity of char which improves its barrier effect rather than increasing the char yield.     

Effect of magnesium dihydroxide nanoparticles on thermal degradation and flame resistance of PMMA nanocomposites

The influence of magnesium dihydroxide (MDH) nanoparticles on thermal degradation and fire behavior of poly(methyl methacrylate) (PMMA) has been investigated by thermogravimetric analysis (TGA), cone calorimeter, and pyrolysis‐combustion flow calorimeter (PCFC) tests, respectively. MDH nanoparticles with either lamellar or fibrous shape have been synthesized via a sol‐gel technique and characterized by transmission electron microscopy (TEM) and X‐ray diffraction analysis. PMMA–MDH nanocomposites have been prepared by melt blending the recovered MDH nanoparticles within PMMA at different loadings (5, 10, and 20 wt% MDH). According to TGA results, the incorporation of lamellar or fibrous MDH nanoparticles into PMMA leads to a significant improvement in PMMA thermal stability, both under air and inert atmosphere. The results obtained by PCFC and cone calorimeter tests show an important decrease in the peak of heat release rate (pHRR) concomitant with charring during the combustion. Lamellar MDH nanoparticles were found to be more efficient than fibrous MDH nanoparticles. Copyright © 2010 John Wiley & Sons, Ltd.     

Preparation and flammability of a novel intumescent flame-retardant poly(ethylene-co-vinyl acetate) system

A phosphorus-containing flame retardant, 4-(5,5-dimethyl-2-oxo-1,3,2-dioxaphosphorinan-2-yloxymethyl)-2,6,7-trioxa-1-phospha-bicyclo[2.2.2]octane-1-oxide (MOPO), was synthesized successfully and characterized. The flame retardancy and thermal behavior of a new intumescent flame-retardant (IFR) system for EVA, which was made of MOPO and ammonium polyphosphate (APP), were investigated by limiting oxygen index (LOI) test, vertical burning test (UL-94), cone calorimeter, and thermogravimetric analysis (TGA). An LOI value of 28.4 and UL-94 V-0 rating can be achieved when the total loading of MOPO and APP was 30 wt.%. The results from cone calorimeter indicate that both the heat release rate (HRR) and the total heat release (THR) of IFR-EVA decreased significantly compared with those of neat EVA. TG curves showed that the amount of residues increased significantly when intumescent additives were added; it also could be found that the LOI values increased with the increase in char residues. Meanwhile, morphology of the residues obtained from burning IFR-EVA in LOI test was studied through the SEM observations and rich compact char layers could explain the excellent flame retardance.     

Flame retardancy and thermal degradation of intumescent flame retardant polypropylene with MP/TPMP

The performances of the novel intumescent flame retardant (IFR) polypropylene (PP) composites containing melamine phosphate (MP) and tris(1‐oxo‐2,6,7‐trioxa‐1‐phosphabicyclo[2,2,2]methylene‐4)phosphate (TPMP) were investigated. The flame retardancy of IFR‐PP system was characterized by limiting oxygen index (LOI) and UL 94 and cone calorimeter. The morphology of the char obtained after cone calorimeter testing was studied by scanning electron microscopy (SEM). The thermal oxidative degradation (TOD) of the composites was investigated by using thermogravimetric analysis (TGA) and real‐time Fourier transform infrared spectroscopy (RT‐FTIR). Compared with the PP/ TPMP or PP/ MP binary composite, at the same addition level, the LOI values of the PP/MP/TPMP ternary composites increase and reach V‐0 at the suitable MP/TPMP ratio. The results of TGA and RT‐FTIR showed the existence of the interaction between IFR and PP. Copyright © 2008 John Wiley & Sons, Ltd.     

Synergistic effect of carbon nanotubes and decabromodiphenyl oxide/Sb2O3 in improving the flame retardancy of polystyrene

Brominated flame retardant polystyrene composites were prepared by melt blending polystyrene, decabromodiphenyl oxide, antimony oxide, multi-wall carbon nanotubes and montmorillonite clay. Synergy between carbon nanotubes and clay and the brominated fire retardant was studied by thermogravimetric analysis, microscale combustion calorimetry and cone calorimetry. Nanotubes are more efficient than clay in improving the flame retardancy of the materials and promoting carbonization in the polystyrene matrix. Comparison of the results from the microscale combustion calorimeter and the cone calorimeter indicate that the rate of change of the peak heat release rate reduction in the microscale combustion calorimeter was slower than that in the cone. Both heat release capacity and reduction in the peak heat release rate in the microscale combustion calorimeter are important for screening the flame retardant materials; they show good correlations with the cone parameters, peak heat release rate and total heat released.     

Flammability and thermal degradation of flame retarded polypropylene composites containing melamine phosphate and pentaerythritol derivatives

The flammability of polypropylene (PP) composites containing intumescent flame retardant additives, i.e. melamine phosphate (MP) and pentaerythritol (PER), dipentaerythritol (DPER) or tripentaerythritol (TPER) was characterized by limiting oxygen index (LOI), UL 94 and the cone calorimeter, and the thermal degradation of the composites was studied using thermogravimetric analysis (TG) and real time Fourier transform infrared (RTFTIR). It has been found that the PP composite containing only MP does not show good flame retardancy even at 40% additive level. Compared with the PP/MP binary composite, the LOI values of the PP/MP/PER (PP/MP/DPER or PP/MP/TPER) ternary composites at the same additive loading are all increased, and UL 94 ratings of most ternary composites studied are raised to V-0 from no rating (PP/MP). The cone calorimeter results show that the heat release rate and smoke emission of some ternary composites decrease in comparison with the binary composite. It is noted from the TG data that initial decomposition temperatures of ternary composites are lower than that of the binary composite. The RTFTIR study indicates that the PP/IFR composites have higher thermal oxidative stability than the pure PP.     

AN S- AND P-CONTAINING FLAME RETARDANT FOR POLYPROPYLENE

A novel charring agent,bis(1-oxo-4-hydroxymethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane) phenylphosphine sulfide (BCPPS),has been synthesized,and it is combined with ammonium polyphosphate (APP) and melamine phosphate (MP) to impart flame retardance and dripping resistance for polypropylene (PP).The fire performance of the treated PP is investigated by limiting oxygen index (LOI),vertical burning test (UL-94) and cone calorimeter,and the thermal stability and thermal oxidative stability of the compos...     

Synergistic effect between a char forming agent (CFA) and microencapsulated ammonium polyphosphate on the thermal and flame retardant properties of polypropylene

The synergistic effect between a char forming agent (CFA) and microencapsulated ammonium polyphosphate (MAPP) on the thermal and flame retardancy of polypropylene (PP) are investigated by limiting oxygen index (LOI), UL‐94 test, cone calorimetry, thermogravimetric analysis (TGA), scanning electron micrograph (SEM), and water resistance test. The results of cone calorimetry show that heat release rate peak (PHRR), total heat release (THR), and the mass loss of PP with 30 wt% intumescent flame retardant (IFR, CFA/MAPP = 1:2) decreases remarkably compared with that of pure PP. The HRR, THR, and mass loss decrease, respectively from 1140 to 100 kW/m², from 96 to 16.8 MJ/m², and from 100 to 40%. The PP composite with CFA/MAPP = 1:2 has the best water resistance, and it can still obtain a UL‐94 V‐0 rating after 168 hr soaking in water. Copyright © 2008 John Wiley & Sons, Ltd.     

Nanoclay synergy in flame retarded/glass fibre reinforced polyamide 6

Exfoliated clay nanocomposites of flame retarded/glass fibre reinforced polyamide 6 were prepared by twin-screw extrusion compounding. A flame retardant system based on phosphorus compounds and zinc borate was used at various levels in glass fibre reinforced PA6 and nanocomposites. Thermal stability and combustion behaviours were evaluated by TGA, LOI, UL94 and cone calorimetry. Substitution of a certain fraction of the flame retardant with nanoclays was found to significantly reduce the peak heat release rate and delay ignition in the cone calorimeter. Moreover, remarkable improvements were obtained in LOI along with maintained UL94 ratings. Residue characterization by FTIR, XRD and SEM ascribed the enhanced flame retardancy of nanocomposite formulations to the formation of a glassy boron/aluminium phosphate barrier reinforced by clay layers at the nanoscale. The physically strong and consolidated barriers formed from nanocomposites were much more effective in impeding heat and mass transfer compared to those from conventional formulations.     

Synthesis of a novel ionic liquid containing phosphorus and its application in intumescent flame retardant polypropylene system

A novel ionic liquid containing phosphorus ([PCMIM]Cl) was synthesized and characterized by FTIR, ¹H NMR, ¹³C NMR and ³¹P NMR. Moreover, a new intumescent flame retardant (IFR) system, which was composed of [PCMIM]Cl and ammonium polyphosphate (APP), was used to impart flame retardancy and dripping resistance to polypropylene (PP). The flammability and thermal behaviors of intumescent flame‐retarded PP (PP/IFR) composites were evaluated by limiting oxygen index (LOI), UL‐94 test, thermogravimetric analysis (TGA) and cone calorimeter test. It was found that there was an obvious synergistic effect between [PCMIM]Cl and APP. When the weight ratio of [PCMIM]Cl and APP was 1:5 and the total amount of IFR was kept at 30 wt%, LOI value of PP/IFR composite reached 31.8, and V‐0 rating was obtained. Moreover, both the peak heat release rate and the peak mass loss rate of PP/IFR composites decreased significantly relative to PP and PP/APP composite from cone calorimeter analysis. The TGA curves suggested that [PCMIM]Cl had good ability of char formation, and when combined with APP, it could greatly promote the char formation of PP/IFR composites, hence improved the flame retardancy. Additionally, the rheological behaviors and mechanical properties of PP/IFR composites were also investigated, and it was found that [PCMIM]Cl could also serve as an efficient lubricant and compatibilizer between APP and PP, endowing the materials with satisfying processability and mechanical properties. Copyright © 2013 John Wiley & Sons, Ltd.     

Calcium and aluminum-based fillers as flame-retardant additives in silicone matrices. III. Investigations on fire reaction

The flame retardancy of silicone composites containing calcium- and aluminum-based fillers has been investigated using several methods including cone calorimeter, Pyrolysis Combustion Flow Calorimeter (PCFC), thermogravimetric analysis and pyrolysis-gas chromatography-mass spectrometry analysis (Py-GC/MS). The fire reaction of precipitated calcium carbonate, calcite, calcium hydroxide, aluminum trihydrate, boehmite and alumina-based composites was correlated mainly with their thermal stability, while for mica and wollastonite-based composites, a barrier effect was also evidenced. The endothermic effect was not established as an efficient flame retardancy mechanism for the silicone composites containing hydrated fillers. Mica composite exhibited the best flame retardancy, in terms of depressed HRR, among all investigated formulations. Finally, a unique behavior was observed during the cone calorimeter test of calcium hydroxide-based composite, which co-crystallization with silica occurs exclusively at high heat flux.     

Synergistic effect of nanoflaky manganese phosphate on thermal degradation and flame retardant properties of intumescent flame retardant polypropylene system

Nanoflaky manganese phosphate (NMP) was synthesized from manganese nitrate and trisodium phosphate dodecahydrate, and used as a synergistic agent on the flame retardancy of polypropylene (PP)/intumescent flame retardant (IFR) system. The thermogravimetric analysis (TGA), real time Fourier-transform infrared (RTFTIR) spectroscopy measurements, cone calorimeter (CONE) and microscale combustion calorimeter (MCC) were used to evaluate the synergistic effects of NMP on PP/IFR system. When IFR + NMP was fixed at 20 wt% in flame retardant PP system, the TGA tests showed that NMP could enhance the thermal stability of PP/IFR system at initial temperature from about room temperature to 440 °C and effectively increase the char residue formation. The RTFTIR results revealed that NMP could clearly change the decomposition behavior of PP in PP/IFR system, which promotes decomposition at the initial temperature from about room temperature to 260 °C and forms more effective barrier layer to protect PP from decomposing at high temperature from about 260 °C to 500 °C. The CONE tests indicated that the addition of NMP in PP/IFR system not only reduced the peak heat release rate (HRR), but also prolonged the ignition time. The MCC results revealed that PP/IFR/NMP system generated less combustion heat over the course of heating than that of PP/IFR system. And scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to explore the char residues of the PP/IFR systems with and without NMP.     

Manufacturing,thermal stability,and flammability properties of polypropylene containing new single molecule intumescent flame retardant

Melamine salt of pentaerythritol phosphate kaolin (MPPK) was synthesized by the reaction of pentaerythritol phosphate with kaolin (K) and melamine. The structure of MPPK was confirmed by EDXS, ¹H NMR, FTIR, and XRD. MPPK was blended with polypropylene (PP) at different loading levels. Thermogravimetric analysis (TGA) results showed that MPPK improved the thermal stability of PP at high temperatures in all PP composites. Vertical burning rate test manifested that PP composites can achieve V0 at 20% and 25% MPPK loading levels. Cone calorimeter data exhibited that addition of 25% MPPK to PP reduced peak of heat release rate (pHRR) and total heat release (THR) by 86% and 76% and increased the char residue after test to 67%. The results of PP/25% MPPK composite were compared with the data obtained from PP containing 25% K and 25% of traditional intumescent flame retardant composed of melamine phosphate (MP), pentaerythritol (PE), and K. The outcomes indicated that MPPK was more efficient in flame retardancy than the other systems. The digital photographs and SEM images for char residue demonstrated that MPPK succeeded in forming cellular and coherent char layer on the PP surface. The main advantage of adding 25% MPPK to PP was its ability to preserve nearly the inner half of the sample without burning after cone calorimeter test.     

Thermal and combustion behavior of polyethersulfone-boehmite nanocomposites

In this paper, we report a thorough study on the thermal stability and fire behavior of polyethersulfone (PES) filled with 2 wt% nano-sized aluminum oxide hydroxide particles (boehmite). The nanocomposite was prepared through melt compounding technique in a co-rotating twin screw extruder. The obtained morphology of the composite was studied by scanning electron microscopy (SEM) coupled with elemental analysis, proving that an even distribution of sub-micron boehmite particles was obtained. PES shear modulus, measured by DMA, is increased by 30% in the boehmite nanocomposite. Thermal stability of the produced materials was studied through thermal gravimetric analysis (TGA), whereas the combustion behavior through cone calorimeter and vertical burning (UL-94) tests. Cone calorimeter results show that a significant overall flame retardant effect was observed due to the presence of boehmite nanoparticles, which could not be detected by UL-94 fire scenario where neat PES is already top ranked V0.     

Synthesis of siloxane‐containing benzoxazine and its synergistic effect on flame retardancy of polyoxymethylene

A type of trialkoxysilane‐containing naphtholoxazine compound (Naph‐boz) was successfully synthesized and combined with ammonium polyphosphate/melamine (APP/ME) as an intumescent flame retardant (IFR) to improve the flame‐retardant efficiency of polyoxymethylene (POM). The Underwriters Laboratories 94 (UL94) vertical burning test, limiting oxygen index (LOI), cone calorimeter, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and Raman spectral analysis were used to study the flame‐retardant properties and related mechanism. The results showed that the formulation with 20 wt.% of APP, 6 wt.% of ME, and 4 wt.% of Naph‐boz passed UL94 V‐1 rating, and the LOI value was improved to 40.3%. Compared with pure POM, the IFR with Naph‐boz had greater reduction in peak heat release rate (lower 74.9%) and total heat release (lower 40.2%). SEM images showed that compact and reinforcing charred layer was formed during the POM/IFR/4Naph‐boz samples combustion, which was beneficial at reducing and maintaining low combustion parameters throughout the cone calorimeter test. The synergistic flame‐retardant effect between Naph‐boz and APP/ME was considered as the reason for the improvement in flame retardancy POM. Furthermore, because of the Naph‐boz was conducive to the compatibility between the flame retardants and matrix, the notched Izod impact strength of POM/IFR/4Naph‐boz composite was higher than that of POM/IFR system.     

Effect on thermal and combustion behaviors of montmorillonite intercalation nickel compounds in polypropylene/IFR system

A new montmorillonite intercalation nickel compound (MINC) was devised and synthesized. MINC was modified by cetyl trimethyl ammonium bromide to obtain organic MINC (OMINC). The results of X‐ray diffraction show that the layer spacing was expanded by nickel compound and cetyl trimethyl ammonium bromide, indicating that OMINC was prepared successfully. OMINC was further incorporated into polypropylene (PP)/intumescent flame retardant (IFR) system for preparing PP/IFR/OMINC nanocomposites via melt blending. In thermogravimetric analysis, PP/IFR/OMINC nanocomposites exhibit an enhanced thermal behavior and residue amount. Vertical burning test (UL‐94) and limited oxygen index results show that PP/IFR/OMINC nanocomposites have excellent flame retardance, i.e. the limited oxygen index value at 29.5 and UL‐94 V0 level for PP/IFR/4 wt% OMINC nanocomposites. According to cone calorimeter testing, the addition of OMINC brings an efficient reduction of flammability parameters, such as peak heat release rate, total heat release, and smoke production rate. Copyright © 2015 John Wiley & Sons, Ltd.     

PP/EVA/OMMT纳米复合材料及其阻燃材料的动态燃烧行为

利用锥形量热仪(CONE)在35kW/m2热辐照条件下,并结合极限氧指数(LOI)和UL-94垂直燃烧测试方法对聚丙烯(PP)/乙烯-醋酸乙烯酯共聚物(EVA)/有机蒙脱土(OMMT)纳米复合材料和加入无卤复配阻燃剂制备的PP/EVA/OMMT/氢氧化铝(ATH)/三氧化二锑(AO)纳米复合阻燃材料的热释放速率、烟释放及材料在燃烧时的质量损失行为进行了研究。结果表明,添加5%(质量分数)OMMT可以提高PP/EVA复合材料的阻燃性能,燃烧时的热释放速率、质量损失率以及烟释放量减少,且OMMT与无卤复配阻燃剂之间可产生阻燃协同作用,使纳米复合阻燃材料的阻燃性能、热稳定性和抑烟性进一步增强。