The flame retardant effect of aluminum phosphinate in combination with zinc borate,borophosphate, and nanoclay in polyamide‐6

The effect of zinc borate (ZnB), borophosphate (BPO₄), and organoclay were studied to improve the flame retardancy of polyamide‐6 composites containing organic phosphinates. The flame retardancy of polyamide‐6 composites was investigated using limiting oxygen index (LOI), Underwriters Laboratories (UL‐94) standard, thermogravimetric analysis, Fourier transform infrared spectroscopy, and mass loss calorimeter. The addition of 15 wt% aluminum phosphinate (AlPi) increased the LOI value from 22.5 to 29.5, and V0 rating was obtained from UL‐94 test. The addition of organoclay, ZnB, and borophosphate does not change the predominant gas phase mechanism of AlPi during LOI and UL‐94 tests. The addition of organoclay increased the condensed phase mechanism of AlPi physically by the protective effect of layered silicate, whereas the addition of ZnB increased the condensed phase mechanism of AlPi chemically by the formation of boron aluminum phosphate species deducted from mass loss calorimeter studies. Copyright © 2012 John Wiley & Sons, Ltd.     

Flame retarding glass fibers reinforced polyamide 6 by melamine polyphosphate/polyurethane‐encapsulated solid acid

Melamine polyphosphate and thermal‐plastic polyurethane (TPU)‐encapsulated solid acid were applied for flame retardant glass fibers reinforced polyamide 6 (GFPA6). The introduction of TPU would change the interfacial property between glass fibers (GFs) and polyamide 6 (PA6), weakening the “candlewick effects” of GFs in PA6. Serving as a synergist, solid acid containing sulfur (CAS) played the role of a strong acid source, which could promote the system to form much more condensed and closed char layers. Macromolecular charring agent, TPU, was able to accelerate the charring process. In addition, TPU encapsulating on the unstable solid acid could isolate CAS from PA6 resin, preventing the chemical interaction between them, which would cause the degradation of material. This established technology provided an effective approach to prepare halogen‐free flame retardant GFPA6 with UL94‐1.6 mm V0 rating and good mechanical performance, showing a promise in the future commercial application. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

二乙基次膦酸铝/三聚氰胺聚磷酸盐复配阻燃三元乙丙橡胶的性能

采用二乙基次膦酸铝(ADP)与三聚氰胺聚磷酸盐(MPP)复配填充三元乙丙橡胶(EPDM),制备了EPDM阻燃材料,研究了ADP/MPP填充量及配比对EPDM燃烧性能及力学性能的影响。结果表明,ADP与MPP复配使用,可提高EPDM的阻燃性能,二者具有协同作用;当二者总添加量为30份、质量比为2∶1时,材料的极限氧指数可达到36%,最大热释放速率下降50.2%,总释放热降低25.9%,总生烟量降低22.3%,且EPDM的力学性能能够满足使用要求,拉伸强度为19.5 MPa,扯断伸长率为427%,邵尔A硬度为78,300%定伸应力为10.3 MPa。     

Preparation of polyamide resin‐encapsulated melamine cyanurate/melamine phosphate composite flame retardants and the fire‐resistance to glass fiber‐reinforced polyamide 6

In this study, melamine cyanurate (MCA)/melamine phosphate (MP) composite flame retardants were synthesized in the solution of phosphoric acid/polyamide 6 (PA6). Phosphoric acid acted as the solvent of PA6, catalyst of melamine‐cyanurate self‐assembly reaction and reactant of melamine‐phosphoric acid reaction. With the consumption of the acid, the pH value of the system increased, and the solved PA6 precipitated on the surface of the flame retardant particles to form polymeric encapsulation. This technology realized the synthesis and surface modification of the flame retardants in one process. The catalyst and solvent, phosphoric acid, was finally converted into the product MP, and need no an additional removing process. The encapsulated MCA/MP (EMCMP) composite flame retardants were successfully applied in the fire‐resistance to glass fiber (GF)‐reinforced PA6. Because the encapsulated layer of EMCMP was also PA6, good interfacial compatibility and effective dispersion of EMCMP in PA6 resin can be obtained, and the corresponding flame retardant materials showed excellent flame retardancy and mechanical performance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1773–1779, 2006     

Effect of different metallic hydroxides on flame‐retardant properties of low density polyethylene/melamine polyphosphate/starch composites

The flame retardancy of synthesized melamine polyphosphate (MPP) in combination with starch (ST) and different metallic hydroxides was investigated in low density polyethylene (LDPE) by limiting oxygen index (LOI) and vertical burning test. The results indicated that the LOI value of composite comprising Al(OH)₃(ATH) was higher than those of composites at the same additive loading with Mg(OH)₂(MH)or Fe(OH)₃(FH), which increased from 22 to 27%. And the composite comprising ATH passed V1 rating without causing molten drops. In addition, thermostability and morphology were characterized by differential scanning calorimeter (DSC), thermogravimetry (TG), derivative thermogravimetry (DTG), and scanning electron microscope (SEM). The results demonstrated that the crystallization of the composites remained unaffected after the incorporation of metallic hydroxide. The thermal degradation behavior of LDPE composites and the morphology of residual charred layer were changed. It also can be concluded that there was a synergy between certain metallic hydroxide and MPP after analyzing the residual charred layer using X‐ray diffraction (XRD). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

磷系阻燃剂FR/APP协效阻燃PP

采用氧指数测定仪、热重分析仪和锥形量热仪研究了磷系阻燃剂1,3,5-三(5,5-二甲基-1,3-二氧杂环己内磷酸基)苯(FR)和聚磷酸铵(APP)复配体系对聚丙烯(PP)材料阻燃性能的影响.结果表明,FR/APP提高了PP的极限氧指数(LOI)、热稳定性和残炭率,降低了热释放速率.当w(FR)为15%和w(APP)为10%复配阻燃PP时,复合材料的LOI为29.6%.阻燃级别达到UL 94 V-0级.     

Melamine polyphosphate/silicon‐modified phenolic resin flame retardant glass fiber reinforced polyamide‐6

The halogen‐free flame retardance of glass fiber reinforced polyamide‐6 (PA6) is an everlastingly challenge due to well‐known wick effect. In this research, a novel system composed of a nitrogen–phosphorous flame retardant, melamine polyphosphate combined with a macromolecular charring agent, silicon‐modified phenolic resin (SPR), was employed to flame‐retard glass fiber reinforced PA6. It exhibited obvious synergistic effect between the two components at a proper ratio range. The flame retardance of the composites can be remarkably improved due to the increased amount and improved thermal stability of the produced char. The flame resistance tests indicated that the synergism system with an optimized ratio achieved V0 (1.6 mm) rating of UL94, 25.2% of Limited Oxygen Index, and only 338.2 W/g of the heat release peak rate. The corresponding synergistic mechanisms were investigated by the characterizations including the thermal gravimetric analysis, carbonation test, and the char morphology observation. It confirmed that the introduced SPR could accelerate the carbonation of PA6 resin, which was in favor of the construction of denser and more continuous charring structure. In addition, the flame retardant materials also indicated the acceptable mechanical properties, showing the advantages in the overall performance. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Influence of morphology and ammonium polyphosphate dispersion on the flame retardancy of polystyrene/nylon‐6 blends

The influences of the distribution of ammonium polyphosphate (APP) in polystyrene/nylon‐6 [PS/polyamide‐6 (PA6)] blends and the continuity of the (PA6 + APP) phase on flame retardancy were investigated. The flame retardant properties were evaluated by limiting oxygen index (LOI), vertical flammability test and cone calorimeter tests. The results showed that APP is exclusively dispersed in the PA6 phase, and (PA6 + APP) phase formed a continuous state when the content of PA6 in PS/PA6 blends was higher than 32% (w/w). For blends with a continuous (PA6 + APP) phase, the decrease of PA6 content caused an increase in LOI values from 26% to 33% and a reduction of peak heat release rate. The improvement of flame retardancy was attributed to the increase of APP concentration in the PA6 phase, which benefited the fast formation of a continuous intumescent charred layer. The transformation of (PA6 + APP) phase morphology from a continuous state to a discontinuous state at a PA6 content of below 32% (w/w) caused a decrease in LOI. Results of thermo‐gravimetric and cone calorimeter tests indicated that the discontinuous intumescent charred layer thus formed could be responsible for the deterioration of flame retardant properties, which was also confirmed by scanning electron microscopy. Copyright © 2013 John Wiley & Sons, Ltd.     

The effect of morphology on the flame‐retardant behaviors of melamine cyanurate in PA6 composites

Three types of melamine cyanurate (MCA) with micrometer‐size sphere‐like, micrometer‐scale rod‐like, and nanometer‐scale flake‐like morphologies were synthesized by changing the chemical circumstances of the reactions. The microcosmic morphologies of MCA were characterized via scanning electron microscopy and X‐ray diffraction. After the MCAs with different morphologies were incorporated into polyamide 6 (PA6), the flame‐retardant properties of the MCA/PA6 composites were investigated using the limited oxygen index (LOI), UL94, and cone calorimeter tests. The MCA/PA6 composites with nanometer‐scale flake‐like MCA obtained an LOI value of 29.5% and a UL94 V‐0 rating, which were higher than those with micrometer‐size sphere‐like and rod‐like MCAs. However, the different morphologies did not affect the heat release rate, total smoke release, average carbon monoxide yield, and average carbon dioxide yield based on the cone calorimeter. The flame‐retardant mechanism of MCAs with different morphologies was investigated via thermal gravimetric analysis (TGA) and TGA‐Fourier transform infrared spectra. The results show that the different morphologies of MCA resulted in different dispersed evenness of MCA. Further, the nanometer‐scale flake‐like morphology of MCA brought more interactions of hydrogen bond between MCA and PA6, which resulted in the delay of MCA decomposition and the enhancement of MCA flame‐retardant effect. The nanometer‐scale flake‐like MCA had a better performance compared with the other samples because of the delaying and even release of flame‐retardant effect by the decomposition of evenly dispersed MCA. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40558.     

杂化三聚氰胺聚磷酸盐的合成及其在聚酰胺6中的阻燃应用

以三聚氰胺、磷酸与类石墨氮化碳（g-C3N4）为原料,通过液相反应合成了杂化三聚氰胺磷酸盐（CNMP）,再通过固相热缩聚制得杂化三聚氰胺聚磷酸盐（CNMPP）,表征了CNMP与CNMPP的结构和热性能。CNMPP随后被应用在阻燃聚酰胺6（FRPA6）中,并采用垂直燃烧测试、极限氧指数测试和灼热丝法研究其阻燃效果。结果表明,与三聚氰胺聚磷酸盐（MPP）相比,CNMPP的热稳定性有所提高,起始热分解温度（热失重5 %时所对应的温度）上升了8.5 ℃,650 ℃残炭率也由34.1 %提升至60.2 %;g-C3N4的杂化还提高了MPP的阻燃性,在添加量均为30 %（质量分数,下同）时,低杂化比例的CNMPP阻燃的聚酰胺6（PA6）自熄时间变短,达到UL 94 V-0级,灼热丝起燃温度升高,极限氧指数从24.2 %提高到29.5 %;但高杂化比例的CNMPP会恶化其阻燃性能。     

The investigation on the flame retardancy mechanism of nitrogen flame retardant melamine cyanurate in polyamide 6

Melamine cyanurate (MCA) flame retardant polyamide 6 (PA6) shows good flame retardancy, but the corresponding mechanisms have not been completely understood. In this paper, Fourier transform infrared spectra (FTIR), elemental analysis (EA), scanning electronmicroscope (SEM), energy dispersive scanning (EDS), thermogravimeric analysis (TGA) and pyrolysis-gas chromatogram-mass spectrometer (Py-GC-MS) were conducted to investigate the processes including melt-drip phase, gaseous phase and condensed phase of MCA/PA6 system. Compared with original PA6, it is found that MCA flame retardant PA6 mainly undergoes predominant weak bond-breakage degradation forming oligomers rather than oxidative degradation producing low-boiling point fuel as original PA6 does. The produced oligomers can accelerate the formation of the melt drips which effectively removes the combustion heat and latent fuel, also the self-condensation of these oligomers is advantageous to form stable cross-linking structure, thus greatly consolidating the char layer.     

玻纤增强聚酰胺6/次磷酸钇复合材料的制备及其阻燃性能

以六水合氯化钇(YCl3?6H2O)和次磷酸钠(NaH2PO2)为原料,采用共沉淀法制备了一种新型稀土金属次磷酸盐-次磷酸钇(YHP),对其进行了表征;以YHP为阻燃剂,采用熔融共混法制备了系列玻纤增强聚酰胺6(GFPA)/次磷酸钇复合材料(GFPA/YHP),采用热重、极限氧指数(LOI)、UL-94垂直燃烧和微型量热测试研究了YHP添加量对复合材料热稳定性、阻燃性能及燃烧性能的影响. 结果表明,YHP已成功制备,其具有棒状结构,长度为20?100 ?m,宽度为5?20 ?m,热稳定性很高,降解温度T5%为410℃,最大热失重速率温度Tmax为412℃,750℃下热解的残炭率为90.8wt%. 加入YHP降低了GFPA/YHP复合材料的热分解温度,但提高了其成炭率和高温稳定性,YHP添加量为20wt%时,复合材料的热分解温度为373℃,最大热失重速率温度为414℃,700℃下热解的残炭率为50.42wt%;YHP可有效提高复合材料的阻燃性能,极限氧指数(LOI)达27.5vol%,垂直燃烧级别达UL-94 V-1级;YHP可有效降低复合材料燃烧过程的热释放速率峰值(PHRR)和总放热(THR)量,二者分别降至327 W/g和15.8 kJ/g,比GFPA分别下降了14.1%和25.4%,表明YHP有效降低了GFPA/YHP复合材料燃烧的火灾危险性.     

聚磷酸蜜胺系膨胀型阻燃剂阻燃PA6的燃烧行为及热裂解研究

采用以聚磷酸蜜胺(MPP)为基的三元膨胀型阻燃剂阻燃聚酰胺6(PA6)，测定了阻燃PA6的氧指数(LOI)、UL94V阻燃性及热稳定性，以傅立叶变换红外光谱(FT—IR)分析了阻燃PA6的热分解残余物，以锥形量热仪(CONE)测定了阻燃PA6的诸多与火灾有关的阻燃参数(包括释热速度、质量损失速度、有效燃烧热、比消光面积等)，并以光电子能谱(XPS)测定了阻燃PA6残炭表面的元素组成及XPS曲线拟合数据。     

Preparation and characterization of flame‐retardant melamine cyanurate/polyamide 6 nanocomposites by in situ polymerization

This article focuses on an improved method, i.e., improved in situ polymerization of ε‐caprolactam in the presence of melamine derivatives to prepare flame‐retardant melamine cyanurate/polyamide 6 (MCA/PA6) nanocomposites. The chemical structures of these synthetic flame retardant composites are characterized by Fourier‐transform infrared spectroscopy and X‐ray diffraction. Morphologies, mechanical properties, and thermal properties also are investigated by the use of transmission electron microscopy, mechanical testing apparatus, differential scanning calorimetry, and thermogravimetric analysis, respectively. Through transmission electron microscopy photographs, it can be found that the in situ‐formed MCA nanoparticles with diametric size of less than 50 nm are nanoscaled, highly uniformly dispersed in the PA6 matrix. These nanocomposites, which have good mechanical properties, can reach UL‐94 V‐0 rating at 1.6‐mm thickness even at a relatively low MCA loading level. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Enhancement of flame retardancy and mechanical properties of polyamide 6 by incorporating melamine cyanurate combined with attapulgite

In this study, the nanocomposites are prepared which used polyamide 6 (PA6) composite as matrix, melamine cyanurate (MCA) as fire retardant and attapulgite (AT) as synergistic agent. The mathematical model between MCA content, AT content, and limited oxygen index (LOI) is established by multiple linear regression fitting. The polymer materials are characterized using Fourier transform infrared spectroscopy, X-ray diffraction, Thermogravimetric Analysis, and scanning electron microscopy. Through response surface methodology, the important variables (polymerization time, the content of MCA, and the content of AT) affecting the mechanical strength of composites are modeled. Results demonstrate that when the t is 0.6 h, the AT content is 6.2%, and the MCA content is 11.5%, the mechanical properties of the PA6/MCA/AT composite are up to 44.81 MPa, and the sample passes the UL-94 V-0 flammability rating, and the LOI reaches 27.9%. Therefore, polymers with highly effective flame retardancy and optimal mechanical properties are prepared. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 47298.     

Preparation of microencapsulated aluminum hypophosphite and flame retardancy and mechanical properties of flame‐retardant ABS composites

Microencapsulated aluminum hypophosphite (MFAHP) with a shell of melamine–formaldehyde resin (MF) was prepared via in situ condensation polymerization. The presence of MFAHP increased the water resistance of flame‐retarded (FR) acrylonitrile–butadiene–styrene (ABS) composites after hot water treatment. The mechanical properties indicate that the tensile strength and flexural strength of the FR ABS/MFAHP composites is enhanced with the incorporation of MFAHP. Cone calorimeter test results demonstrated that the peak heat release rate, total heat release, and total smoke release values of the ABS/MFAHP composites were significantly decreased. Digital photos and scanning electron microscopy images of the residues of ABS/25 wt % MFAHP₂ composites exhibited compact char layer structures, with many cobweb‐like nanoparticle arrangements formed on the surface by the burning process. The investigation of flame‐retardant mechanisms of ABS/MFAHP composites using infrared spectroscopy and energy‐dispersive X‐ray spectroscopy indicated that both the formation of char residue in the condensed phase and the release of inert gases by the MF shell in the gas phase led to the formation of compact and stable char layers containing carbon/pyrophosphate and aluminum polyphosphate, consequently leading to the good flame‐retardant performance of MFAHP. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45008.     

An easy‐to‐obtain silicone‐containing flame retardant and its effects on the combustion of polycarbonate

A novel silicone‐containing flame retardant (HSOBA) synthesized from hydrogen‐containing silicone oil and Bisphenol A via a simple approach has been incorporated into polycarbonate (PC) matrix to study its effects on the flame retardancy. The flame retardancy of PC/HSOBA composites is investigated by limiting oxygen index (LOI), vertical burning tests (UL‐94), and cone calorimeter measurement. The LOI value of the composites is 31.7 and the UL‐94 rating reaches V‐0, when the content of HSOBA is 3 wt %. Cone calorimeter data confirm that the HSOBA acts as an effective additive functioning both as flame retardants and as smoke suppressant. Evolution of the thermal behaviors of the composites tested by TGA, the morphological structures, and the constituent of char residue after LOI tests characterized by scanning electronic microscopy‐energy‐dispersive X‐ray analysis were used to explain the possible flame‐retardant mode. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synergistic flame‐retarded effect between carbon nanotubes and ammonium polyphosphate in Nylon6 and Nylon6/polystyrene blends

The association of carbon nanotubes (CNTs) and ammonium polyphosphate (APP) as flame retardants was utilized for improving the flame retardancy of nylon6 (PA6) and blends of PA6/Polystyrene (PS). A remarkable synergistic effect between APP and CNTs was observed in PA6 at 1‐wt% CNTs loading. Rheological tests showed that 1‐wt% CNTs formed a network structure. Morphology of residue char indicated that a network enhanced synergistic effect. A synergy between APP and CNTs in blends of PA6/PS (56/24) was also investigated. APP and CNTs exhibited a remarkable synergistic effect at 0.25‐wt% CNTs loading, but the antagonistic effect on flame retardancy of blends was observed at 1‐wt% CNTs loading. Transmission electron microscopy showed that CNTs were exclusively dispersed in the PA6 phase of blends. The selective dispersion of CNTs caused the formation of a network at 0.25‐wt% CNTs loading. Morphology of residue char indicated that 0.25‐wt% CNTs were benefited by the formation of a continuous and well‐swollen residue char that enhanced the synergistic effect in blends. However, the aggregation of 1‐wt% CNTs in PA6 phase caused high viscosity of PA6 phase, resulting in a poor expansion of the residue char. Consequently, the antagonism was exhibited.     

Melamine cyanurate surface treated by nylon of low molecular weight to prepare flame‐retardant polyamide 66 with high flowability

In the present research, a nitrogen‐based flame‐retardant, melamine cyanurate (MCA) was surface‐treated with low‐molecular‐weight nylon through a solvent process to further improve its flowability and dispersion. The surface energy and flow energy of the modified MCA were investigated. The properties of polyamide 66 (PA66) prepared with surface‐treated and with conventional MCA were evaluated and compared. Because of lower surface energy and flow energy for modified MCA, its agglomeration degree and flow resistance are obviously decreased compared with conventional MCA, thus achieving finer and more homogenous dispersion in the PA66 matrix. Moreover, the low‐molecular‐weight nylon resin encapsulating MCA surface will melt at lower temperature during compounding with PA66; hence, it serves as a lubricant and carrier to further improve the flowability and dispersion of the flame retardants. Based on these advantages, the modified MCA flame‐retardant PA66 achieves much better flame retardancy, flowability, and mechanical properties compared with conventional MCA/PA66 under the same loading level of flame retardant (10 wt%).     

Enhanced mechanical properties and fire retardancy of polyamide 6 nanocomposites based on interdigitated crystalline montmorillonite–melamine cyanurate

Polyamide 6 (PA6)–montmorillonite (MMT)–melamine cyanurate (MCA) nanocomposites were prepared by the incorporation of interdigitated crystalline MMT–MCA. Their morphologies were assessed by X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, thermal stability measurement by thermogravimetric analysis, mechanical properties measurement by tensile tests, and fire retardancy measurement by limiting oxygen index testing and vertical burning testing (UL‐94). The results indicate that MMT–MCA was homogeneously nanodispersed in PA6. Compared with PA6–MCA, the PA6–MMT–MCA nanocomposites showed enhanced thermal stability. The mechanical properties and fire retardancy show that the PA6–MMT–MCA nanocomposites with 5 wt % total loading of MMT–MCA reached UL‐94 V‐2 rating (3.2 mm) and significantly increased the tensile strength of PA6 up to 24.8 % with only 1 wt % MMT in PA6. Through the control the weight ratio of MMT and MCA in MMT–MCA, the Young's modulus of PA6 could be adjusted in a very wide range (300–1100 MPa) because of the dual role of the rigid MMT and nonrigid MCA layers. The reinforced mechanism of the mechanical properties was also investigated. Consequently, the PA6–MMT–MCA nanocomposites with a good nanodispersing ability, improved thermal stability, excellent mechanical properties, and good flame retardancy were obtained and could provide broad prospects for wider applications for PA6 materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46039.