Flame retardation and thermal degradation of intumescent flame‐retarded polypropylene composites containing spirophosphoryldicyandiamide and ammonium polyphosphate

A novel halogen‐free intumescent flame retardant, spirophosphoryldicyandiamide (SPDC), was synthesized and combined with ammonium polyphosphate (APP) to produce a compound intumescent flame retardant (IFR). This material was used in polypropylene (PP) to obtain IFR‐PP systems whose flammability and thermal behavior were studied by the limiting oxygen index (LOI) test, UL‐94, thermogravimetric analysis, and cone calorimetry. In addition, the mechanical properties of the systems were investigated. The results indicated that the compound intumescent flame retardant showed both excellent flame retardancy and antidripping ability for PP when the two main components of the IFR coexisted in appropriate proportions. The optimum flame retardant formulation was SPDC:APP = 3:1, which gave an LOI value of 38.5 and a UL‐94 V‐0 rating. Moreover, the heat release rate, production of CO, smoke production rate, and mass loss rate of the IFR‐PP with the optimum formulation decreased significantly relative to those of pure PP, according to the cone calorimeter analysis. The char residues from the cone calorimetry experiments were observed by scanning electron microscopy, which showed that a homogeneous and compact intumescent char layer was formed. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers     

A novel halogen‐free intumescent flame retardant containing phosphorus and nitrogen and its application in polypropylene systems

A novel halogen‐free intumescent flame retardant, pentaerythritol spirobisphosphoryl‐dicyandiamide (SPDC), was synthesized and characterized by FTIR, ¹H NMR, and ³¹P NMR spectra. The new flame retardant was used in polypropylene (PP) to prepare flame‐retardant materials whose flammability and thermal behavior were studied by the limiting oxygen index (LOI) method, thermogravimetric analysis (TGA), and cone calorimetry (CONE). The mechanical properties were also investigated. The results indicated that when the addition of SPDC reached 30 wt%, the material showed both excellent flame retardancy and anti‐dripping abilities for PP. Moreover, the LOI value of the PP‐IFR(30%) was 32.5, and it passed the UL‐94 V‐0 rating test. The CONE results revealed that in PP, SPDC(30%) significantly decreased the peak heat release, total heat release, and smoke relative to their values for pure PP. The morphological structures observed by SEM demonstrated that SPDC could promote the formation of a homogeneous and compact intumescent char layer. The TGA data showed that SPDC could enhance the thermal stability of PP and effectively increase the char residue formation. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers     

改性聚磷酸铵对三嗪类膨胀阻燃聚丙烯性能的影响

由改性聚磷酸铵(APP)、自制的三嗪类成炭发泡剂(CFA)等复配制成膨胀型阻燃剂(IFR),以二氧化硅、二氧化钛等为协效剂阻燃聚丙烯(PP)。研究了不同组分的IFR及协效剂对阻燃PP复合材料阻燃性能、力学性能和耐水性能的影响。结果表明:改性APP的亲水性下降;由改性APP/CFA(4/1)、二氧化硅协效剂复配的PP复合材料阻燃性能、力学性能优良,助剂在PP基体中分散性好,热水浸泡后氧指数为32.5%,仍能达到UL94V—1级,失重率为2.92%。     

Synergistic effect between aluminum hypophosphite and a new intumescent flame retardant system in poly(lactic acid)

A hyperbranched charring agent (CT) was synthesized by triglycidyl isocyanurate and diethylenetriamine in water, and a new intumescent flame retardant (IFR) system was formed by ammonium polyphosphate (APP) and CT. The different formula and synergistic system between IFR and aluminum hypophosphite (AHP) have been studied through limit oxygen index (LOI), UL‐94, cone calorimetry test and TGA. It was found that the LOI for poly(lactic acid) (PLA) with 30 APP/CT (4:1) and 20 wt % IFR/AHP (3:1) were 41.2% and 43.5%, respectively, and the both could achieve UL‐94V‐0 rating with no melt dripping. The heat release rate (HRR), maximum HRR value and average mass loss rate of PLA could be dramatically decreased by combination of IFR and AHP while the thermal stability was greatly enhanced. The study of morphology and structure of char illustrated that more intumescent and compact char layer with good intensity was formed during the degradation of IFR/AHP, which resulting to better flame retardancy and anti‐dripping than IFR or AHP alone. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46359.     

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.     

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.     

新型磷-氮膨胀阻燃剂在改性聚丙烯中的应用研究

采用自制干法合成的磷-氮膨胀型阻燃剂(磷酸酯三聚氰胺盐,IFR)复配聚磷酸胺(APP)和聚四氟乙烯(PT-FE)阻燃改性聚丙烯(PP),利用极限氧指数法、垂直燃烧法分析了阻燃PP的燃烧性能,通过热重分析仪、傅里叶变换红外光谱仪、扫描电子显微镜和X射线光电子能谱对阻燃PP的热降解过程、燃烧性能、残炭结构进行了分析,并研究了燃烧过程中复配阻燃体系对PP的阻燃机理。结果发现,IFR、APP和PTFE之间具有明显的阻燃协效作用;当阻燃剂总添加量为24%(APP为6%、IFR为17.5%、PTFE为0.5%)(质量分数)时,阻燃PP的极限氧指数达到30.1%,垂直燃烧测试达UL 94V-0级;加入阻燃剂还能提高PP的热稳定性。     

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 effects of hydroxy silicone oil on intumescent flame retardant polypropylene system

The effects of hydroxy silicone oil as a synergistic agent on the flame retardancy of intumescent flame retardant polypropylene composites (IFR-PP) were studied, and the IFR system mainly consisted of the ammonium polyphosphate (APP), melamine (MEL) and pentaerythritol (PER). The UL 94 rating, thermogravimetric analysis (TGA), cone calorimeter (CONE) and digital photograph were used to evaluate the synergistic effects of hydroxy silicone oil (HSO). It has been found that the PP composite containing only APP, MEL and PER does not show good flame retardancy at 30% additive level. The cone calorimeter results show that the heat release rate, mass loss rate, mass, total heat release, carbon monoxide and carbon dioxide of PP/APP/MEL/PER/HSO composites decrease in comparison with the PP/APP/MEL/PER composite. The digital photographs demonstrated that HSO could promote to form the homogenous and compact intumescent char layer. Thus, a suitable amount of HSO plays a synergistic effect in the flame retardancy.     

Synthesis of amino trimethylene phosphonic acid melamine salt and its application in flame‐retarded polypropylene

Amino trimethylene phosphonic acid melamine salt (MATMP) was synthesized and used as acid source and blowing agent in intumescent flame‐retarded polypropylene (PP); its compositions were characterized by Fourier transform infrared spectroscopy and X‐ray powder diffraction. An intumescent flame retardant (IFR) system composed of MATMP, pentaerythritol (PER), and PP was tested by limiting oxygen index (LOI), UL‐94, cone calorimeter tests, and thermogravimetric analysis and compared with an ammonium polyphosphate (APP)/PER system. The results showed that MATMP had better water resistance than APP, the LOI value of PP/MATMP/PER composite can reach 30.3%, and a UL‐94 V‐0 rating can be reached at 25 wt % IFR loading. The amount of residual char of IFR MATMP/PER was 20.3 and 9.5 wt % at 400 and 600 °C, respectively. A thermooxidative degradation route and a possible flame‐retardant mechanism of IFR were proposed according to the analysis of evolved gases and residual chars. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46274.     

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.     

Synthesis and characterization of a novel charring agent and its application in intumescent flame retardant polypropylene system

A novel halogen‐free charring agent bi(4‐methoxy‐1‐phospha‐2, 6, 7‐trioxabicyclo [2.2.2]‐octane‐1‐sulfide) phenylphosphate (BSPPO) was synthesized from phenylphosphonic dichloride (PPDC), and 4‐hydroxymethyl‐1‐phospha‐2, 6, 7‐trioxabicyclo[2.2.2]‐octane‐1‐sulfide (SPEPA) which was synthesized from pentaerythritol and thiophosphoryl chloride in this article. The structure of BSPPO and SPEPA was characterized by Fourier transform infrared (FTIR), ¹H‐NMR, ¹³C‐NMR, and ³¹P‐NMR. Combined with ammonium polyphosphate (APP) and melamine pyrophosphate (MPP), the flame retardance and dripping resistance of BSPPO added in polypropylene (PP) were investigated. The fire performance of the flame retardant PP system was investigated by limiting oxygen index (LOI), vertical burning test (UL‐94), and cone calorimeter. The thermal stabilities of the composites were studied by thermogravimetric analysis (TGA). The flame retardance mechanism was investigated by FTIR and scanning electronic micrograph (SEM). The mechanical properties and water solubility were also investigated. The residue of BSPPO is 40.6% at 600°C, which indicates BSPPO has excellent charring ability. The char residue of the polypropylene intumescent flame retardant (PP‐IFR) system is 22% at 600°C, which suggests that the flame retardation synergy of APP, BSPPO, and MPP is good. With the optimum formulation, the LOI of the IFR‐PP system is 32.0, and the UL‐94 is V‐0 rating. The heat release rate (HRR), total heat release (THR), smoke production rate (SPR), total smoke production (TSP), and mass loss rate (MLR) of IFR‐PP with the optimum formulation decrease significantly comparing to pure PP from cone calorimeter analysis. The FTIR and SEM results indicate that the char properties and the char yield have direct effect on the flame retardance and antidripping behaviors. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

氧化锌对膨胀阻燃聚丙烯的影响

研究了协效剂氧化锌（ZnO）对聚磷酸铵（APP）、季戊四醇（PER）、氰尿酸三聚氰胺（MCA）膨胀阻燃聚丙烯（PP）体系的阻燃协效作用。采用氧指数（LOI）、热失重法（TG）、锥形量热仪（Cone）、红外光谱（FTIR）等手段分析了ZnO对膨胀阻燃PP的影响。结果表明，氧化锌可提高该体系的LOI和阻燃性能，还可促进阻燃体系形成炭层，且可提高其炭层的强度，该体系氧化锌最佳用量应为1．0份。     

不同聚合度成炭剂在膨胀阻燃聚丙烯中的应用研究

以三聚氯氰、乙胺、乙醇胺和乙二胺为原料,通过控制物料比合成了4种不同聚合度的成炭-发泡剂(CFA)。将合成的CFA与聚磷酸铵(APP)及纳米二氧化硅复配成膨胀阻燃剂并添加到聚丙烯(PP)中,制备阻燃PP材料。通过热重分析、氧指数、垂直燃烧和力学性能测试研究了材料的热稳定性、阻燃性能和力学性能。结果表明:随着CFA聚合度的增加,膨胀阻燃体系对PP材料的阻燃效率相应提高;阻燃剂的加入提高了PP材料的热稳定性,CFA聚合度的变化对阻燃PP材料的力学性能影响不大。当CFA的聚合度为40时,阻燃PP材料的阻燃性能和热稳定性能均达到最佳。     

EG与IFR复合阻燃ABS的动态燃烧性和协同效应

将可膨胀石墨(EG)与P-N型膨胀阻燃剂(IFR)复合阻燃丙烯腈-丁二烯-苯乙烯共聚物(ABS)树脂,阻燃剂添加量为20%(质量分数,下同),通过极限氧指数(LOI)仪、垂直燃烧测试(UL-94)仪、锥形量热(CONE)仪和扫描电镜(SEM)研究了EG与IFR复合阻燃ABS的协同效应。结果表明,EG/IFR质量比为1/1为最佳配比,阻燃ABS的LOI达到29%,UL-94为V-0级;EG与IFR复合阻燃ABS,表现出一定的协同作用;通过SEM观察ABS/EG/IFR试样燃烧后样品发现,EG与IFR起到协同阻燃作用。     

A novel intumescent flame‐retardant system for flame‐retarded LLDPE/EVA composites

A new intumescent flame retardant (IFR) system consisting of ammonium polyphosphate (APP) and charing‐foaming agent (CFA) and a little organic montmorillonite (OMMT) was used in low‐density polyethylene (LLDPE)/ethylene‐vinyl acetate (EVA) composite. According to limiting oxygen index (LOI) value and UL‐94 rating obtained from this work, the reasonable mass ratio of APP to CFA was 3 : 1, and OMMT could obviously enhance the flame retardancy of the composites. Cone calorimeter (CONE) and thermogravimetric analysis (TGA) were applied to evaluate the burning behavior and thermal stability of IFR‐LLDPE/EVA (LLDPE/EVA) composites. The results of cone calorimeter showed that heat release rate peak (HRR‐peak) and smoke production rate peak (SPR‐peak) and time to ignition (TTI) of IFR‐LLDPE/EVA composites decreased clearly compared with the pure blend. TGA data showed that IFR could enhance the thermal stability of the composites at high temperature and effectively increase the char residue. The morphological structures of the composites observed by scanning electron microscopy (SEM) and X‐ray diffraction (XRD) demonstrated that OMMT could well disperse in the composites without exfoliation, and obviously improve the compatibility of components of IFR in LLDPE/EVA blend. The morphological structures of char layer obtained from Cone indicated that OMMT make the char layer structure be more homogenous and more stable. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

有机-金属杂化化合物阻燃聚丙烯的研究

将有机-金属杂化三嗪化合物（SCTCFA-ZnO）与聚磷酸铵（APP）复配制备了膨胀型阻燃剂（IFR）,通过极限氧指数测试、垂直燃烧测试、锥形量热分析、热失重分析和扫描电子显微镜分析等表征方法研究了SCTCFA-ZnO/APP的协同作用对PP复合材料阻燃性能的影响。结果表明,APP与SCTCFA-ZnO复配可以有提高PP材料的阻燃性能,当IFR的添加量为25 %（质量分数,下同）,且APP/SCTCFA-ZnO的质量比为2/1时,复合材料的极限氧指数最高,达到31.1 %,达到UL 94 V-0级;IFR可提高复合体系的温热稳定性,阻燃复合材料燃烧后会形成一层致密、连续的炭层,从而起到良好的阻燃效果。     

Synergist flame retarding effect of ultrafine zinc borate on LDPE/IFR system

The flame retardancy of low‐density polyethylene (LDPE) treated with complex flame retardant composed of ultrafine zinc borate (UZB) and intumescent flame retardant (IFR) have been investigated by limited oxygen index (LOI), UL‐94 test, thermogravimetric analysis (TGA), cone calorimeter test, scanning electron micrograph (SEM), energy‐dispersive spectrometer (EDS), and X‐ray diffraction (XRD). The results of LOI and UL‐94 test indicate the desired flame retardancy of LDPE is obtained when the mass ratio of UZB to IFR is 4.2 : 25.8 and the complex flame retardant mass content is 30% (based on LDPE). The results of cone calorimeter show that heat release rate (HRR) peak, total heat release (THR), and mass loss of LDPE/IFR/UZB decrease substantially when compared with those of LDPE/IFR. TGA results show that the residue of LDPE/IFR/UZB increases obviously than that of LDPE/IFR when the temperature is above 600°C. SEM indicates the quality of char forming of LDPE/IFR/UZB is superior to that of LDPE/IFR. The results of EDS and XRD indicate that boron orthophosphate (BPO₄) and zinc‐contained compounds are formed in the residual char and these substances may play an important role in stabilizing the intumescent char structure and decrease the degradation speed substantially when subjected to high temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3667–3674, 2007     

Application of a novel halogen‐free intumescent flame retardant for acrylonitrile‐butadiene‐styrene

A novel intumescent flame retardant (IFR), containing ammonium polyphosphate (APP) and poly(tetramethylene terephthalamide) (PA4T), was prepared to flame‐retard acrylonitrile‐butadiene‐styrene (ABS). The flame retardation of the IFR/ABS composite was characterized by limiting oxygen index (LOI) and UL‐94 test. Thermogravimetric analysis (TGA) and TGA coupled with Fourier transform infrared spectroscopy (TG‐FTIR) were carried out to study the thermal degradation behavior of the composite and look for the mechanism of the flame‐retarded action. The morphology of the char obtained after combustion of the composite was studied by scanning electron microscopy (SEM). It has been found the intumescent flame retardant showed good flame retardancy, with the LOI value of the PA4T/APP/ABS (7.5/22.5/70) system increasing from 18.5 to 30% and passing UL‐94 V‐1 rating. Meanwhile, the TGA and TG‐FTIR work indicated that PA4T could be effective as a carbonization agent and there was some reaction between PA4T and APP, leading to some crosslinked and high temperature stable material formed, which probably effectively promoted the flame retardancy of ABS. Moreover, it was revealed that uniform and compact intumescent char layer was formed after combustion of the intumescent flame‐retarded ABS composite. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

十溴二苯乙烷阻燃PBT性能研究

以十溴二苯乙烷(DBDPE)替代传统的十溴二苯醚(DBDPO)作为聚对苯二甲酸丁二醇酯(PBT)的阻燃剂,采用垂直燃烧(UL94)、氧指数(LOI)和锥形量热仪(CONE)方法研究了以十溴二苯乙烷阻燃的PBT的阻燃性能。结果表明:试样的氧指数最高为31.6%,垂直燃烧达到V0级,热释放速率、总热释放和有效燃烧热等数据明显降低,阻燃效果良好。