Polydimethylsiloxane wrapped aluminum diethylphosphinate for enhancing the flame retardancy of polyamide 6

Aluminum diethylphosphinate (ADP) was wrapped with polydimethylsiloxane (PDMS) by a facile method to improve its hydrophobic properties. The morphology and properties of PDMS-modified ADP (PDMS-ADP) were investigated by thermogravimetric analysis, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and water contact angle tests. The water contact angle of PDMS-ADP was increased from 126° to 151° as compared with that of ADP, which indicates that PDMS-ADP showed good hydrophobic properties. Then, ADP and PDMS-ADP were introduced into polyamide 6 (PA6) matrices to study the flame retardancy of the composites. The flammability of the PA6/ADP and PA6/PDMS-ADP composites was much lower than that of pure PA6. The composites PA6-1 (with the addition of 15 wt% ADP) and PA6-4 (with the addition of 12 wt% PDMS-ADP) could pass the UL-94 V-0 in the vertical burning test. Meanwhile, the peak heat release rates of PA6-1 and PA6-4 were 212 and 192 kW/m², with reductions of 67.3 and 70.4%, respectively, compared with pure PA6. These results indicated that the coating of PDMS could enhance the flame-retardant efficiency of ADP.     

Flame retardancy of glass fiber reinforced high temperature polyamide by use of aluminum diethylphosphinate: thermal and thermo‐oxidative effects

Glass fiber reinforced polyamide (PA) 6 T/DT flame retarded with aluminum diethylphosphinate (AlPi) was tested to assess its flame retardant properties. Models for the decomposition of PA 6T/DT with and without AlPi are presented. Thermal decomposition was measured by performing TGA with Fourier transform infrared (FTIR) spectroscopy and FTIR spectroscopy in the condensed phase. Fire behavior was studied using a cone calorimeter and flammability was tested with UL 94 and the limiting oxygen index. AlPi works as an effective flame retardant for glass fiber reinforced PA 6T/DT materials, acting in the gas phase. Also observed was condensed‐phase action, which occurs especially under oxidative conditions before the samples ignite. © 2013 Society of Chemical Industry     

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.     

硅酸盐阻燃木材的阻燃性能和热性能研究

通过二次浸渍工艺获得了硅酸盐阻燃木材样品,通过极限氧指数(LOI)测试了样品的阻燃性能,通过热分析结合扫描电子显微镜(SEM)研究了样品的热降解过程。结果表明:通过二次浸渍工艺可获得阻燃性能优良的阻燃木材,过渡金属硅酸盐可有效的催化木材第二阶段的降解反应,促进炭的生成,还可以在高温下形成熔体覆盖在剩炭的表面,有效提高剩炭的稳定性,同时隔绝可燃性气体的逸出,避免热量和O2的进入,使木材具有良好的阻燃性能。     

Synergistic effects of aluminium hypophosphite on the flame retardancy and thermal degradation behaviours of a novel intumescent flame retardant thermoplastic vulcanisate composite

ABSTRACT

The synergistic effects of aluminum hypophosphite (AHP) on the flame retardancy, thermal degradation behaviors of a novel intumescent flame retardant thermoplastic vulcanizate (TPV/IFR) composite were investigated. The results showed that the combination of AHP with IFR showed evident synergistic effects on the increase in the LOI value and reduction of the combustion parameters for the TPV/IFR/AHP composites at the optimum weight ratio of IFR/AHP (6/1) as evidenced by LOI, UL-94 and CCT. The TGA data revealed that AHP could change the degradation behavior of TPV/IFR composites and enhance the thermal stability of the TPV/IFR composites at high temperature. The results of FTIR, EDXS, LRS and SEM demonstrated that TPV/IFR/AHP composites could form more continuous, dense and stable char layer on the materials surface, and consequently improving the flame retardancy. Based on these results, the possible condensed flame retardant mechanism of TPV/IFR/AHP composites was concluded in detail.     

Effect of a novel phosphorus‐containing compound on the flame retardancy and thermal degradation of intumescent flame retardant polypropylene

A novel flame retardant, tetra(5,5‐dimethyl‐1,3‐ dioxaphosphorinanyl‐2‐oxy) neopentane (DOPNP), was synthesized successfully, and its structure was characterized by FT‐IR, ¹H NMR, and ³¹P NMR. The thermogravimetric analysis (TGA) results demonstrate that DOPNP showed a good char‐forming ability. Its initial decomposition temperature was 236.4°C based on 1% mass loss, and its char residue was 41.2 wt % at 600°C, and 22.9 wt % at 800°C, respectively. The flame retardancy and thermal degradation behavior of novel intumescent flame‐retardant polypropylene (IFR‐PP) composites containing DOPNP were investigated using limiting oxygen index (LOI), UL‐94 test, TGA, cone calorimeter (CONE) test, and scanning electron microscopy (SEM). The results demonstrate that DOPNP effectively raised LOI value of IFR‐PP. When the loading of IFR was 30 wt %, LOI of IFR‐PP reached 31.3%, and it passed UL‐94 V‐0. TGA results show that DOPNP made the thermal decomposition of IFR‐PP take place in advance; reduced the thermal decomposition rate and raised the residual char amount. CONE results show that DOPNP could effectively decrease the heat release rate peak of IFR‐PP. A continuous and compact char layer observed from the SEM further proved the flame retardance. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

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.     

Effect of water erosion on flame retardancy of high-impact polystyrene/magnesium hydroxide composite and its mode of action

High-impact polystyrene (HIPS) flame retarded by magnesium hydroxide (MH) was treated in water at different conditions. The effect of water erosion on flame retardancy of the HIPS/MH composite and its mode of action was investigated by various means. The results indicate that both limiting oxygen index value and UL-94 rating of the HIPS/MH composite decrease observably after water erosion. The average heat release rate, average mass loss rate, total heat release, and total smoke release of the composite all increase remarkably after water erosion. The MH content in the surface layer of the HIPS/MH composite reduces, and the surface of this composite becomes rough and porous after erosion. The water-eroded composite shows a loose and discrete surface morphology after subjected to fire, which favors heat transfer and mass exchange between flame area and the underlying polymers. Consequently, both flame retardancy and smoke suppression of the polymer composite decrease significantly. The decrease in flame retardancy occurs in condensed phase. The result of this work has provided a basis for further investigations to prevent this detrimental effect induced by water erosion.     

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.     

硼酸锌协效二乙基次膦酸铝阻燃PA6

采用硼酸锌(ZB)与二乙基次膦酸铝(ADP)协同阻燃聚酰胺6(PA6).对其阻燃性能和力学性能进行了探讨,并运用垂直燃烧、极限氧指数、锥形量热、热失重分析、扫描电子显微镜以及拉曼光谱对阻燃机理进行了探究.结果表明,ZB作为协效剂,与ADP的协同阻燃效果显著;当在PA6中添加1.5％(质量分数,下同)ZB和8.5％ADP...     

Study on flame‐retardancy and thermal degradation behaviors of intumescent flame‐retardant polylactide systems

Two intumescent flame‐retardant (IFR) additives, IFR‐I and IFR‐II, were synthesized and their structure was confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance. Polylactide (PLA) was modified by the two IFRs to obtain flame‐retardant composites. The flammability of the PLA/IFR composites was characterized by the vertical burning test UL‐94 and limiting oxygen index. The limiting oxygen index values of the PLA composites increased with increase of IFR content. The PLA composite with 20 wt% IFR‐I could pass the UL‐94 V0 rating, while the composite with 30 wt% IFR‐II could not. The results of pyrolysis combustion flow calorimetry showed that the heat release capacity of PLA composites with 30 wt% IFR‐I decreased 43.1% compared with that of pure PLA. The thermal degradation and gas products of PLA/IFR‐I systems were monitored by thermogravimetric analysis and thermogravimetric analysis infrared spectrometry. Scanning electron microscopy was used to investigate the surface morphology of the char residue. Copyright © 2011 Society of Chemical Industry     

Interfacial modification of high impact polystyrene magnesium hydroxide composites effects on flame retardancy properties

High impact polystyrene (HIPS)/magnesium hydroxide (MH) composites were prepared by melt‐blending. Two kinds of interfacial modifiers were used in this research, maleinated poly[styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene] (SEBS‐g‐MA) triblock copolymer and PS. The effects of the use levels of SEBS‐g‐MA on the flame retardancy of HIPS/elastomer/MH based on unmodified and PS‐modified surface were investigated by TEM, FTIR, and combustion tests (horizontal burning test and cone calorimetry). The combustion results showed that comparing composites containing unmodified MH, the flame retarding properties of composites containing PS‐modified MH were obviously improved. The increased performance can be explained that the PS covered on the surface of MH could further improve dispersion of the filler in matrix. Furthermore, there existed a critical thickness of interfacial boundary for optimum flame‐retarding properties in both ternary composites based MH and PS‐modified MH. When the interfacial boundary relative thickness is less than 0.53, the introduction of SEBS‐g‐MA can improve the dispersion degree, leading the improvement of flame retardancy properties. However, with the increase of interfacial boundary thickness, the SEBS‐g‐MA coating around MH acted as a heat and mass transfer barrier, leading to the reduction of flame retardancy. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Enhanced flame retardancy and thermal stability of zinc borate and magnesium carbonate as a promising alternative for Sb2O3 toward polyvinyl chloride

Inorganic zinc compounds such as zinc carbonate (ZC) and zinc borate (ZB) are considered as promising alternatives for harmful antimony trioxide in the future, but may result in poor thermal stability for flexible polyvinyl chloride (PVC). To enhance the flame retardancy and static thermal stability of flexible PVC, zinc compounds with environmentally friendly magnesium carbonate (MC) were introduced into PVC matrix. Findings reveal that the simultaneous use of 5 phr ZB and 5 phr MC for flexible PVC exhibits satisfactory properties containing pronounced flame retardancy with a limiting oxygen index of 30.2% and a UL-94 V-0 rating without dripping, enhanced static thermal stability with high color stability by discoloration tests, reduced smoke emission, and decent mechanical properties, which are advantageous over the standalone use of ZC, ZB, and MC. The enhancement mainly due to that the incorporation of ZB can accelerate the dehydrochlorination and promote the charring of flexible PVC in the early stage of flame burning, and MC can perform the long-term static thermal stability due to the HCl absorption capacity.     

Influence of char-forming lignin in combination with aluminium phosphinate on thermal stability and combustion properties of polyamide 11 blends

Polyamide 11 (PA) blends based on char-forming industrial lignin and aluminum phosphinate (AlP) were prepared to improve flame retardant (FR) properties using a green and eco-friendly approach. This study investigates the thermal degradation and combustion behavior of PA blends prepared by using AlP in combination with two different types of industrial lignins (i.e., kraft lignin (DL) and lignosulphonate lignin (LL). Thermogravimetric (TG) analysis showed that ternary blends containing LL and AlP developed higher char residue up to 10.7 wt% upon decomposition in inert atmospheres. The combination of lignin and AlP increases the thermal stability by shifting the initial decomposition temperature (T_5%) and temperature at maximum decomposition (T_max) to a higher temperature range, attributed to the stabilization of decomposition products. Furthermore, combustion behavior studied by cone calorimeter (forced combustion) and pyrolysis combustion flow calorimeter (PCFC) tests presented a significant reduction in the peak of heat release rate (PHRR) and total heat release (THR). It was found that LL and AlP-containing blends more effectively decreased fire parameters like PHRR and THR than that of DL and AlP-containing blends. The best interaction with reduced fire-retardant properties was obtained when 10 wt% loading of lignin (DL/LL) and AlP was used. The reduction in heat release parameters was mainly ascribed to the condensed phase mechanism by forming an efficient protective char layer, which acts as a barrier against heat and mass transfer between the condensed and the gas phases. Raman spectroscopy analysis also confirmed the formation of the protective graphitic layer in the condensed phase.     

Synergistic effects of magnesium oxysulte whisker and multiwalled carbon nanotube on flame retardancy,smoke suppression,and thermal properties of polypropylene

In this work, multiwalled carbon nanotube (MWCNT)-modified magnesium oxysulfate whisker (MOSw) (MOSw-MWCNT) is successfully synthesized via a facial hydrothermal method. MWCNT is bonded on the surface of MOSw via a bidentate bridging mode of the carboxylate ligation without changing their crystal structures. Then MOSw-MWCNT is incorporated into polypropylene (PP) matrix to prepare series of PP/MOSw-MWCNT composites via melt blending. Cone calorimetry test, horizontal and vertical test, and limit oxygen index (LOI) results all show a significant synergistic effect of MOSw and MWCNT on flame-retardant PP. PP/7MOSw-3MWCNT composite exhibits the lowest peak heat release rate, total heat release, peak smoke production rate, total smoke production, and burning speed of 332.3 kW/m², 87.4 MJ/m², 0.0212 m²/s, 47.7 m² and 23.2 mm/min, respectively. The LOI value of PP/7MOSw-3MWCNT composite is increased to 23.1% from 18.0% of neat PP. The scanning electron microscopy and Raman spectra of residue char indicate that the degree of graphitization and compactness of the residue char are increased with the amount of MWCNT. The introduction of MOSw and MWCNT both improves the thermal stability of PP matrix, but the excess MWCNT leads to the decomposition of the unstable residue char since its excellent thermal conductivity.     

Effect of talc on thermal stability and flame retardancy of polycarbonate/PSBPBP composite

A novel flame retardant poly(3-aminopropyl methylsiloxane bis(3-hydroxy phenyl spirocyclic pentaerythritol bisphosphate)) (PSBPBP) in combination with talc was blended into polycarbonate (PC) by melt compounding. The flame retardancy and thermal stability of PC/PSBPBP/talc composites were investigated by limiting oxygen index (LOI) test, UL-94 rating test, thermogravimetric analysis (TGA), Raman spectroscopy (RS), and scanning electron microscope (SEM). The mechanical properties were also measured in this work. Increasing talc content leads to observed improvement on flame retardancy of PC composites. LOI value of PC/PSBPBP/10 wt % talc system was 34, and this system passed V0 rating in the UL-94 test. The char yield at 700°C was 28.2% and the onset decomposition temperature shifted up to 540°C for PC/10% PSBPBP/10% talc system in TGA. In the Raman measure, the R value and G linewidth of PC/PSBPBP with 10 wt % talc composite increased to 1.41 and 65 cm⁻¹ from 1.12 and 43 cm⁻¹ of pure PC, respectively. The Raman results suggest that the char residue of PC/PSBPBP with talc composites was denser and had better barrier property, which is agreement with the SEM results. Besides, talc had no remarkable influence on the mechanical properties of PC/PSBPBP composites. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

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.     

Synergistic effects of aluminum hydroxide,red phosphorus,and expandable graphite on the flame retardancy and thermal stability of polyethylene

The flame-retardant low-density polyethylene (LDPE) composites loading aluminum hydroxide (ATH), red phosphorus (RP), and expandable graphite (EG) were successfully prepared. The flame retardancy, the thermo-oxidative stability, and the mechanical property of the composites were investigated. The synergistic effect of ATH, RP, and EG on the flame-retardant property and thermal behavior of LDPE were observed. The limiting oxygen index value of LDPE significantly increased from 17.1% to 25.4% upon the incorporation of 15 wt.% of the mixture of three fillers with ATH:RP:EG mass ratio of 1:1:1; and this composite achieved the V-0 classification of the UL94 vertical burning test. The thermogravimetric analysis of this composite under air atmosphere revealed that its residue weight remained 27.89% at 900°C. Furthermore, the results of tension tests indicated that the surface modification of ATH by magnesium stearate and RP by poly(methylhydrosiloxane) noticeably improved the tensile strength and the elongation of the composite.     

Preparation of aluminum diethyl hypophosphite intercalation-modified montmorillonite AlPi-MMT and its effect on the flame retardancy and smoke suppression of thermoplastic polyester elastomer

An aluminum diethyl hypophosphite intercalation-modified montmorillonite flame retardant (AlPi-MMT) is successfully prepared and characterized by FT-IR, SEM, and X-ray diffraction. It is found that thermoplastic polyester elastomer (TPEE) composites incorporating 15 wt% AlPi-MMT flame retardant exhibited better char formation and flame retardant properties compared to those incorporating 15 wt% (4:1, w:w) AlPi and MMT. And the char residual of TPEE/AlPi-MMT at 700°C is 16.17%, which is higher than that of TPEE/AlPi-MMT at 13.94%. and the former can pass UL-94 V-0 rating test while the latter can only pass UL-94 V-1 rating test. Afterwards, the combustion performance of TPEE composites is characterized, and it is found that the heat release and smoke release of TPEE/AlPi-MMT are greatly reduced compared with those of pure TPEE and TPEE/AlPi/MMT, which is a flame retardant and smoke suppressant TPEE composite. Finally, by analyzing the residual char morphology and elements of TPEE composites after combustion, the mechanism of the flame retardant AlPi-MMT to promote char formation and flame retardancy is demonstrated.     

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.