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.     

Influence of the pentaerythritol phosphate melamine salt content on the combustion and thermal decomposition process of intumescent flame‐retardant ethylene–vinyl acetate copolymer composites

Pentaerythritol phosphate melamine salt (PPMS) as a single‐molecule intumescent fire retardant was synthesized and characterized. The influence of the PPMS content on the combustion and thermal decomposition processes of intumescent‐flame‐retardant (IFR) ethylene–vinyl acetate copolymer (EVA) composites was studied by limiting oxygen index (LOI) measurement, UL 94 rating testing, cone calorimetry, thermogravimetric analysis, and scanning electron microscopy. The LOI and UL 94 rating results illustrate that PPMS used in EVA improved the flame retardancy of the EVA composites. The cone calorimetry test results show that the addition of PPMS significantly decreased the heat‐release rate, total heat release, and smoke‐production rate and enhanced the residual char fire performance of the EVA composites. The IFR–EVA3 composite showed the lowest heat‐release and smoke‐production rates and the highest char residue; this means that the IFR–EVA3 composite had the best flame retardancy. The thermogravimetry results show that the IFR–EVA composites had more residual char than pure EVA; the char residue yield increased with increasing PPMS content. The analysis results for the char residue structures also illustrated that the addition of PPMS into the EVA resin helped to enhance the fire properties of the char layer and improve the flame retardancy of the EVA composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42148.     

Flame retardancy and water resistance of novel intumescent flame‐retardant oil‐filled styrene–ethylene–butadiene–styrene block copolymer/polypropylene composites

A novel halogen‐free flame‐retardant composite consisting of an intumescent flame retardant (IFR), oil‐filled styrene–ethylene–butadiene–styrene block copolymer (O‐SEBS), and polypropylene (PP) was studied. On the basis of UL‐94 ratings and limiting oxygen index (LOI) data, the IFRs consisted of a charring–foaming agent, ammonium polyphosphate, and SiO₂ showed very effective flame retardancy and good water resistance in the IFR O‐SEBS/PP composite. When the loading of IFR was only 28 wt %, the IFR–O‐SEBS/PP composite could still attain a UL‐94 V‐0 (1.6 mm) rating, and its LOI value remained at 29.8% after a water treatment at 70°C for 168 h. Thermogravimetric analysis data indicated that the IFR effectively enhanced the temperature of the main thermal degradation peak of the IFR–O‐SEBS/PP composites because of the formation of abundant char residue. The flammability parameters of the composites obtained from cone calorimetry testing demonstrated that water treatment almost did not affect the flammability behavior of the composite. The morphological structures of the char residue and fractured surfaces of the composites were not affected by the water treatment. This was attributed to a small quantity of IFR extracted from the composite. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39575.     

Effect of charring agent THEIC on flame retardant properties of polypropylene

Tris(2‐hydroxyethyl) isocyanurate (THEIC) was used as charring agent and combined with ammonium polyphosphate (APP) to form an intumescent flame retardant (IFR) for polypropylene (PP). The flame retardancy and combustion performance of PP/IFR composite was tested by limiting oxygen index (LOI), UL‐94 vertical burning test and cone calorimeter. The results showed that PP/IFR composite had highest LOI of 34.8 and obtained V‐0 rating when 30 wt % IFR was loaded and mass ratio APP/THEIC was 2 : 1. The peak heat release (PHRR) and total heat release (THR) values of PP composite containing FRs were remarkably reduced compared with that of pure PP. However, water resistant test demonstrated the PP/IFR composite had poor flame retardant durability, both the LOI value and UL‐94 V‐rating decreased when PP/IFR composite was soaked in water at 70°C after 36 h. The degradation process and the char morphology of IFR and PP/IFR composite were investigated by TGA and SEM images. The possible reaction path between APP and THEIC in the swollen process was proposed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41214.     

Synergistic effects of dual imidazolium polyoxometalates on intumescent flame retardant polypropylene

The role of dual imidazolium polyoxometalates (POMs) in the flame retardancy of polypropylene/intumescent flame retardant (PP/IFR) composites was studied. The results showed that the structures of dual imidazolium POMs have a great effect on the flame retardancy of PP composites. The dual imidazolium POMs based on an ethyl group (EMIPMA) obtain the best flame retardant efficiency. With 15.5 wt % IFR and 0.5 wt % EMIPMA, the PP composites reach a limiting oxygen index of 25.7 and the UL‐94 V‐0 standard. However, the dual imidazolium POMs containing a butyl (BMIPMA) or hexyl (HMIPMA) group cannot achieve the UL‐94 V‐0 standard at the same formulation. Dual imidazolium POMs not only promote the formation of good char, but also induce the formation of intumescent char with a hierarchical and microporous structure that helps to prevent gas and heat from transferring from the flame to the resin. Therefore, the flame retardancy of PP/IFR composites is improved. However, excessive combustible components produced by BMIPMA or HMIPMA deteriorate the flame retardancy of PP/IFR composites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45491.     

Synthesis of novel triazine charring agent and its effect in intumescent flame‐retardant polypropylene

A novel charring agent (CNCA‐DA) containing triazine and benzene ring, using cyanuric chloride, aniline, and ethylenediamine as raw materials, was synthesized and characterized. The effects of CNCA‐DA on flame retardancy, thermal degradation, and flammability properties of polypropylene (PP) were investigated by limited oxygen index (LOI), vertical burning test (UL‐94), thermogravimetric analysis (TGA), and cone calorimeter test (CCT). The TGA results showed that CNCA‐DA had a good char forming ability, and a high initial temperature of thermal degradation; the char residue of CNCA‐DA reached 18.5% at 800°C; Ammonium polyphosphate (APP) could improve the char residue of APP/CNCA‐DA system, the char residue reached 31.6% at 800°C. The results from LOI and UL‐94 showed that the intumescent flame retardant (IFR) containing CNCA‐DA and APP was very effective in flame retardancy of PP. When the mass ratio of APP and CNCA‐DA was 2 : 1, and the IFR loading was 30%, the IFR showed the best effect; the LOI value reached 35.6%. It was also found that when the IFR loading was only 20%, the flame retardancy of PP/IFR can still pass V‐0 rating in UL‐94 tests, and its LOI value reached 27.1%. The CCT results demonstrated that IFR could clearly change the decomposition behavior of PP and form a char layer on the surface of the composites, consequently resulting in efficient reduction of the flammability parameters, such as heat release rate (HRR), total heat release (THR), smoke production rate (SPR), total smoke production (TSP), and mass loss (ML). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synergistic effect of phosphorus-containing nanosponges on intumescent flame-retardant polypropylene

A novel nanosponge (NS) was synthesized via the crosslinking of β-cyclodextrin with epoxy resin. Subsequently, a phosphorus-containing nanosponge (P–NS) was prepared by the absorbance of resorcinol bis(diphenyl phosphate) into the NS, and it was used as a synergistic agent of intumescent flame retardance in a polypropylene (PP)/melamine pyrophosphate/pentaerythritol composite. The synergistic effect between P–NS and the intumescent flame retardant (IFR) was investigated by thermogravimetry, limiting oxygen index (LOI) testing, vertical burning (UL-94) testing, cone calorimeter testing, and scanning electron microscopy (SEM). The results show that P–NS significantly improved the flame retardancy of the PP/IFR composite. When 3.0 wt % P–NS replaced the same amount of IFR in the composite, the LOI value increased from 29.0 to 32.5%, the UL-94 rating was enhanced from V-1 to V-0, and the peak heat release rate decreased substantially from 343 to 235 kW/m². Simultaneously, the total heat release and mass loss rate decreased dramatically. Furthermore, the SEM results show that the quality of char formation of the PP/IFR/P–NS was superior to that of the PP/IFR composite. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Flammability,thermal stability,and mechanical properties of ethylene-propylene-diene monomer/polypropylene composites filled with intumescent flame retardant and inorganic synergists

Three kinds of inorganic particles, zinc borate (ZB), organic montmorillonite (OMMT), and expanded graphite (EG) as synergistic flame retardants, are incorporated into ethylene-propylene-diene monomer/polypropylene (EPDM/PP) composites filled with intumescent flame retardants (IFR). The effect of three synergistic flame retardants on the combustion, thermal stability, and mechanical properties of the EPDM/PP/IFR composites are investigated by limiting oxygen index (LOI), UL-94 test, cone calorimeter test (CCT), thermogravimetric analysis (TGA), scanning electron microscopy, mechanical property testing, and dynamic mechanical analysis (DMA). The results from LOI, UL-94, and CCT show that the synergistic effect of IFR with ZB and EG is better than IFR with OMMT in the flame retardant EPDM/PP/IFR composites. The TGA results indicate that the thermal stability and char residues of the composites is improved with the addition of inorganic particles, which is attributed to the formation of dense char layers to isolate heat flow. DMA results including storage modulus (G'), loss modulus (G"), and loss factor (tan δ) suggest that the composites with inorganic particles exhibit more rubber-filler interaction, which limits the movement of the rubber chains.     

Enhancement of wollastonite on flame retardancy and mechanical properties of PP/IFR composite

Wollastonite, a natural calcium metasilicate possessing acicular crystal habit structure, was used together with intumescent flame retardant (IFR) to flame retard polypropylene (PP). The synergistic effects between wollastonite and IFR were investigated using limiting oxygen index (LOI) test, cone calorimeter test, thermogravimetric analysis, scanning electron microscope‐energy dispersive spectrometer (SEM‐EDS), etc. The results revealed that wollastonite could effectively improve mechanical properties and flame retardancy of the PP/IFR composite. When 2.0 wt% wollastonite substituted for the same amount of IFR in the composite, the impact strength was enhanced from 4.6 kJ/m² to 6.8 kJ/m², which was increased by 47.1%. Meanwhile, the LOI was increased from 33.0% to 35.5%, a UL‐94V‐0 rating was achieved and the peak heat release rate decreased substantially from 314.4 kW/m² to 262.8 kW/m². Furthermore, the SEM‐EDS results provided positive evidence that the quality of char layer of the PP/IFR/wollastonite was superior to that of the PP/IFR composite due to synergism between wollastonite and IFR. POLYM. COMPOS., 35:158–166, 2014. © 2013 Society of Plastics Engineers     

含磷钛酸酯偶联剂改性膨胀型阻燃剂及其阻燃聚丙烯的研究

采用含磷钛酸酯偶联(剂PTCA)对由三聚氰胺焦磷酸(盐MPP)和季戊四(醇PER)复配组成的膨胀型阻燃(剂IFR)进行表面改性,并用其制备阻燃聚丙烯(PP)。研究了PTCA用量对PP/IFR共混物力学性能和阻燃性能的影响,并通过热重分析和扫描电镜对共混物进行了表征。结果表明:PTCA有效改善了IFR与PP基体的相容性,提高了PP/IFR共混物的力学性能及阻燃性能。当PTCA用量为1.0%时,共混物的拉伸强度和缺口冲击强度为27.3 MPa和3.2 kJ/m2,分别比未改性的PP/IFR提高了18.7%和6.7%;LOI从未改性PP/IFR的28.5%提高到31.5%,且通过UL94 V-0级;此外,共混物的热稳定性也明显提高,700℃时的残炭率由未改性PP/IFR的8.2%提高到12.1%。     

Preparation of a chitosan‐based flame‐retardant synergist and its application in flame‐retardant polypropylene

A novel flame‐retardant synergist, chitosan/urea compound based phosphonic acid melamine salt (HUMCS), was synthesized and characterized by Fourier transform infrared spectroscopy and ³¹P‐NMR. Subsequently, HUMCS was added to a fire‐retardant polypropylene (PP) compound containing an intumescent flame‐retardant (IFR) system to improve its flame‐retardant properties. The PP/IFR/HUMCS composites were characterized by limiting oxygen index (LOI) tests, vertical burning tests (UL‐94 tests), microscale combustion calorimetry tests, and thermogravimetric analysis to study the combustion behavior and thermal stability. The addition of 3 wt % HUMCS increased the LOI from 31.4 to 33.0. The addition of HUMCS at a low additive amount reduced the peak heat‐release rate, total heat release, and heat‐release capacity obviously. Furthermore, scanning electron micrographs of char residues revealed that HUMCS could prevent the IFR–PP composites from forming a dense and compact multicell char, which could effectively protect the substrate material from combusting. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40845.     

Flame Retardancy and Thermal Performance of Polypropylene Treated With the Intumescent Flame Retardant,Piperazine Spirocyclic Phosphoramidate

Piperazine spirocyclic phosphoramidate (PSP), a novel halogen‐free intumescent flame retardant, was synthesized and used to improve the flame retardancy and dripping resistance of polypropylene (PP) combined with ammonium polyphosphate (APP) and a triazine polymer charring‐foaming agent (CFA). The optimum flame‐retardant formulation was PSP:APP:CFA = 3:6:2 (weight ratio). The flammability and thermal behavior of the (intumescent flame‐retardant)‐PP (IFR‐PP) were investigated via limiting oxygen index (LOI), vertical burning tests (UL‐94), thermogravimetric analysis, and cone calorimetry (CONE). The results indicated that the IFR‐PP had both excellent flame retardancy and anti‐dripping ability. The optimum flame‐retardant formulation gave an LOI value of 39.8 and a UL‐94 V‐0 rating to PP. Moreover, both the heat release rate and the total heat release of the IFR‐PP with the optimum formulation decreased significantly relative to those of pure PP, according to the cone calorimeter analyses. The residues of IFR‐PP obtained after CONE tests were observed by scanning electron microscopy, and it was found that the char yield was directly related to the flame retardancy and anti‐dripping behavior of the treated PP. J. VINYL ADDIT. TECHNOL., 20:10–15, 2014. © 2014 Society of Plastics Engineers     

Synthesis of a bio-based triazine derivative and its effects on flame retardancy of polypropylene composites

A triazine derivative CC–Cy was synthesized using cytosine (Cy) and cyanuric chloride (CC). The CC–Cy was used as a charring agent and combined with ammonium polyphosphate (APP) to form an intumescent flame-retardant (IFR) system. The IFR system was applied to improve the flame retardancy of polypropylene (PP). Moreover, bisphenol-A bis(diphenyl phosphate) (BDP) was introduced in the IFR system to regulate the suitability between the IFR and PP. The results showed the PP containing 20 wt % APP and 5 wt % CC–Cy achieves the UL-94 V-2 rating. While the PP with 18 wt % APP/CC-Cy (4:1) and 3 wt % BDP obtains the UL-94 V-0 rating indicating the improved flame-retardant efficiency. Thermal degradation behaviors and char morphology both showed that the reactions between APP and CC–Cy promote the formation of char residues, and BDP works in gas phase to enhance the flame retardancy of PP composites. Thus, a synergistic IFR system based on APP, CC–Cy, and BDP is formed, which can protect PP from fire effectively. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 47367.     

纳米SiO2对PP/MPP/PEPA膨胀阻燃体系的协同作用

以纳米SiO,为阻燃协效剂,采用多聚磷酸蜜胺(MPP)和茏状季戊四醇磷酸酯(PEPA)复配阻燃剂,制备具有良好阻燃性能的无卤阻燃聚丙烯(PP).研究纳米SiO2用量对PP阻燃性能和协效作用的影响.结果表明:添加少量的纳米SiO2可提高PP的阻燃性能;当纳米SiO2添加量为1%时,阻燃PP的氧指数达28.5%.TGA和FTIR分析及SEM和体式显微镜观测结果表明:添加少量的纳米SiO2可促进体系成炭,稳定炭层,从而提高材料的阻燃性能.     

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.     

焦磷酸哌嗪/MCA对聚丙烯的阻燃作用

通过垂直燃烧试验、极限氧指数(LOI)测定和锥形量热分析,对焦磷酸哌嗪(DPP)与三聚氰胺氰尿酸盐(MCA)复合而成的膨胀型阻燃剂(IFR)阻燃聚丙烯(PP)进行了研究。结果表明:当m(MCA):m(DPP)为1.0∶2.5,IFR质量分数为26%时,PP的LOI为34.2%,垂直燃烧试验可通过V-0级;与PP相比,阻燃PP的热释放速率(HRR)、总热释放量(THR)分别降低了91.34%,31.42%。该IFR对PP的阻燃机理与聚磷酸铵基IFR的类似,主要是通过凝聚相阻燃。     

Percolation and catalysis effect of bamboo‐based active carbon on the thermal and flame retardancy properties of ethylene vinyl‐acetate rubber

The effect of percolation and catalysis of bamboo‐based active carbon (BAC) on the thermal degradation and flame retardancy of ethylene vinyl‐acetate rubber (EVM) composites with intumescent flame retardants (IFR) consisting of ammonium polyphosphate (APP) and dipentaerythritol (DPER) has been investigated. The vulcanization characteristics were analyzed by a moving die rheometer. Thermogravimetric analysis (TGA) and fire behavior tests such as limiting oxygen index (LOI), vertical burning (UL 94), and cone calorimetry were used to evaluate the thermal properties and flame retardancy of EVM composites. Scanning electron microscopy (SEM) was used to study the morphology of residues of EVM composites. The addition of BAC significantly increased the maximum torque (M_H) of EVM composites and EVM matrices. The combination of IFR with BAC can improve the thermal stability of EVM composites. Moreover, BAC can enhance char residue and promote the formation of a network for IFR. The current EVM/37IFR/3BAC composite achieved an LOI of 33.6% and a UL 94 V‐0 rating. The PHRR, total heat release (THR), and total smoke release (TSR) for EVM/IFR/BAC were greatly reduced as compared to EVM/40IFR. Also, the mechanical properties of the EVMIFR/BAC composites increased with increasing BAC contents. The physical percolation effect between BAC and EVM before and after thermal degradation, and the chemical catalysis effect between BAC and IFR during thermal degradation are responsible for the improved flame retardancy of EVM composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42414.     

氧化锌催化膨胀型阻燃剂对PP阻燃及力学性能的影响

研究了氧化锌催化膨胀型阻燃剂(APP/PER)对PP阻燃和力学性能的影响。研究表明,当APP/PER质量比为20/10,ZnO的质量分数为1．3%时,阻燃PP的LOI值达到最大;同时阻燃PP的拉伸强度和冲击强度比不含ZnO的PP有所提高。TG结果表明,ZnO的加入使阻燃PP燃烧时降解过程加快并生成更多的剩炭,形成稳定的保护层,从而提高了PP的阻燃效果。SEN的形貌观察表明,加入ZnO的试样燃烧炭膜孔径较小、孔膜较厚。     

润滑剂对PP/IFR复合材料性能的影响

以聚丙烯(PP)为基体树脂、FR–1420为无卤膨胀型阻燃剂,分别加入乙撑双硬脂酰胺(EBS)、聚乙烯(PE)蜡、硬脂酸锌(硬锌)、硅酮及聚偏氟乙烯(PVDF)等五种润滑剂来制备阻燃PP复合材料(PP/IFR),考察了润滑剂及其含量对PP/IFR的阻燃性能和力学性能的影响,并对材料的热分解行为及炭层结构进行了表征和分析。结果表明,FR–1420含量为21%,五种润滑剂含量在0.5%~2%范围内变化时,对PP/IFR复合材料的力学性能影响不大,而对阻燃性能产生了明显影响;EBS与阻燃剂产生对抗作用,不论添加量多少,都显著降低PP/IFR的阻燃性,垂直燃烧等级由V–0级降低至无级;PE蜡、硬锌、硅酮及PVDF的添加量都存在一个最大值,当低于最大值时,不会影响PP/IFR的阻燃性,垂直燃烧等级均为V–0级,而高于最大值时,则会降低PP/IFR的阻燃性;PE蜡、硬锌、硅酮及PVDF均会不同程度延后PP/IFR的起始分解温度,略微降低其成炭率。     

Synthesis of a novel oligomeric intumescent flame retardant and its application in polypropylene

A novel oligomeric phosphorous‐nitrogen containing intumescent flame retardant, poly (4,4‐diamino diphenyl methane‐O‐bicycli pentaerythritol phosphate‐phosphate) (PDBPP), was synthesized and characterized. Thermal stability and flammability properties of polypropylene (PP)/PDBPP composites with various PDBPP loading were investigated by thermogravimetric analysis (TGA), limited oxygen index (LOI), and cone calorimeter, respectively. The results showed that the incorporation of PDBPP could improve both the thermal stability and flame retardancy of PP considerably. PP/30%PDBPP system had a LOI value of 28 and its peak heat release rate was reduced by 60% relative to pure PP. Infrared spectrum and field emission scanning electron microscope measurements revealed that PDBPP and PP/PDBPP composites would form a continuous multicellular char layer containing phosphoric acid when exposed to elevated temperature. It was suggested that the very char layer was responsible for the enhanced thermal stability and improved flame retardancy. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers