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.     

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     

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     

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.     

The mechanical properties and thermal performances of polypropylene with a novel intumescent flame retardant

A novel intumescent flame retardant: tetra‐spirophosphoryl‐benzoguanamine (TSPB) containing three constituents was used as a new flame retardant for polypropylene to prepare flame‐retardant materials, whose flammability and thermal behavior were studied by the limited oxygen index (LOI), thermogravimetric analysis (TGA), in addition whose mechanical properties were investigated in this work. It was found that when the addition of TSPB was 25 wt %, the LOI value of the PP could achieve to 29.5 and pass the UL‐94 V‐0 rating test. The TGA data showed that TSPB could enhance the thermal stability of PP and effectively increase the char residue formation. The mechanical performance test showed that the addition of TSPB improve the mechanical performances of PP to some extent. Thus, the trinity intumescent flame retardant TSPB is good to modify PP. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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     

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     

Synergistic effects of fumed silica on intumescent flame‐retardant polypropylene

The synergistic effects of fumed silica on the thermal and flame‐retardant properties of intumescent flame retardant (IFR) polypropylene based on the NP phosphorus‐nitrogen compound have been studied by Fourier transfer infrared (FTIR) spectroscopy, cone calorimeter test (CCT), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), limiting oxygen index (LOI), and UL‐94 tests. The LOI and UL‐94 data show that when ≤1 wt % fumed silica substituted for the IFR additive NP can increase 2 to 4% LOI values of the PP blends and keep the V‐0 rating. The data obtained from the CCT tests indicate the heat release rates (HRR) reduce by about 23% for the PP/NP sample with 0.5 wt % fumed silica, whereas the mass loss rates (MLR) and total heat release (THR) values are much lower than those of the PP/NP samples without fume silica. The TGA data demonstrate that a suitable amount of fumed silica can increase the thermal stability and charred residue of the PP/IFR/SiO₂ blends after 500°C. The morphological structures of charred residues observed by SEM give positive evidence that a suitable amount of fumed silica can promote the formation of compact intumescent charred layers and prevent the charred layers from cracking, which effectively protects the underlying polymer from burning. The dynamic FTIR spectra reveal that the synergistic flame‐retardant mechanism of a suitable amount of fumed silica with IFR additive is due to its physical process in the condensed phases. However, a high loading of fumed silica restricts the formation of charred layers with P? O? P and P? O? C complexes formed from burning of polymer materials and destroys the swelling behavior of intumescent charred layers, which deteriorates the flame retardant and thermal properties of the PP/IFR blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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     

Synthesis,thermal degradation,and flame retardance of novel triazine ring‐containing macromolecules for intumescent flame retardant polypropylene

Two novel triazine ring‐containing macromolecules, designated as charring‐foaming agent 1 (CFA1) and charring‐foaming agent 2 (CFA2), were synthesized by a series of polycondensation reactions. Their chemical structures were analyzed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (¹³C solid‐state NMR), and elemental analysis, and their thermal degradation properties were assessed by thermogravimetric analysis (TGA). TGA data revealed that CFA1 and CFA2 show high thermal stability and have a high propensity for char formation, their initial decomposition temperatures being 300.2°C and 287.1°C, and their char residues at 800°C amounting to 32.2 wt % and 21.1 wt %, respectively. CFA1 presents higher thermal stability and more char residue than CFA2. Based on experimental results of the flame retardancy (limiting oxygen indices values and UL‐94 V‐0 rating) and the TG data of new intumescent flame retardant polypropylene (IFR‐PP) containing CFA1 and CFA2, CFA1 exhibits more outstanding intumescent flame retardance than CFA2. IFRs containing CFA1 and CFA2 enhanced Notched Izod Impact strength of IFR‐PP, and slightly lower tensile strength of IFR‐PP. IFR2 shows more advantageous effect on mechanical properties of IFR‐PP than IFR1. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of tris(2‐hydroxyethyl) isocyanurate homopolymer and its application in intumescent flame retarded polypropylene

A macromolecular homopolymer (named as Homo‐THEIC) was synthesized through self‐etherification of tris(2‐hydroxyethyl) isocyanurate (THEIC) molecules and used as charring agent. Its chemical structure was characterized by FTIR and ¹³C‐NMR. The charring agent was mixed with ammonium polyphosphate (APP) and applied in flame retarded polypropylene (PP). Results of UL‐94, LOI, and cone calorimeter test showed that the LOI of flame retarded PP can reach 32.8% and UL‐94 V‐0 rating can be achieved at 30 wt % loading. The heat release rate and smoke production rate during the combustion of PP were substantially reduced. TGA results indicated that the synergistic effect between APP and Homo‐THEIC existed and the addition of intumescent flame retardant (IFR) dramatically enhanced the thermal stability of PP. According to the results of TGA, SEM, TG‐FTIR, FTIR, and Raman, the char forming process of IFR can be separated into three stages: the formation of viscous phosphate ester (T _onset?330 °C), the expanding process along with the decomposition of phosphate ester and the release of a large amount of gases (330–480 °C), and the final formation of graphitic‐like char without any expanding feature (480–670 °C). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44663.     

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.     

Flame retardancy,mechanical, and thermal properties of waterborne polyurethane conjugated with a novel phosphorous‐nitrogen intumescent flame retardant

A novel phosphorous‐nitrogen intumescent flame retardant with reactive diamino groups, benzoguanamine spirocyclic pentaerythritol bisphosphonate (BSPB), was synthesized and used as a chain extender, and then a series of flame retardant waterborne polyurethanes (FRWPU) were prepared by covalently conjugating the BSPB into waterborne polyurethane (WPU) backbone. Their structures were characterized by Fourier transformed infrared spectrometry (FTIR), ¹H and ³¹P nuclear magnetic resonances (NMR), respectively. Simultaneously, the flame retardancy and the thermal stability of FRWPU were systematically investigated by limiting oxygen index (LOI) test, UL‐94 vertical burning test and thermogravimetric analysis (TGA). The results indicated that with the increase of BSPB content from 0 to 8 wt%, the LOI value of FRWPU increased from 18.6 to 27.3%, showing significant improvement by 8.7%. Compared with WPU, FRWPU showed decreased thermal stability but promoted char residue ratio. Conjugation of BSPB could obviously enhance the mechanical properties of FRWPU, the Young's modulus and tensile strength dramatically increased with the increase of BSPB. Investigation of char forming mechanism of BSPB through real time Fourier transform infrared spectra (RTFTIR) and scanning electronic microscopy (SEM) revealed that the polyphosphoric acid and phosphorus oxynitrides rich outer intumescent char layer could form protective shields to inhibit effectively internal polyurethane to heat and flame diffusion during contacting fire. POLYM. COMPOS., 38:452–462, 2017. © 2015 Society of Plastics Engineers     

An efficient approach to improving fire retardancy and smoke suppression for intumescent flame‐retardant polypropylene composites via incorporating organo‐modified sepiolite

In this work, an efficient approach to improving the fire retardancy and smoke suppression for intumescent flame‐retardant polypropylene (PP) composites is developed via incorporating functionalized sepiolite (organo‐modified sepiolite [ONSep]). The PP composites with different amounts of intumescent flame retardants and ONSep were prepared by melt compounding. The morphology, thermal behavior, fire retardancy, smoke suppression, and mechanical property of flame‐retardant PP composites were studied. The results indicate an appropriate amount of ONSep in the flame‐retardant PP composites can increase thermal degradation temperature and char formation as well as a reduction of the peak heat release rate and total heat release; moreover, the addition of ONSep significantly decreases the CO production, total smoke production, smoke production rate, and smoke temperature. Simultaneously, the impact strength of intumescent flame‐retardant PP composite is also maintained by introducing an appropriate amount of ONSep as compared with that without ONSep.     

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。     

Influence of polyamide 6 as a charring agent on the flame retardancy,thermal, and mechanical properties of polypropylene composites

In this work, polyamide 6 (PA6) as a charring agent has been used in combination with thermoplastic polyurethane (TPU)‐microencapsulated ammonium polyphosphate (MTAPP) forming intumescent flame retardants (IFRs) which applies in polypropylene (PP). The effects of the IFRs on the flame retardancy, morphology of char layers, water resistance, thermal properties and mechanical properties of flame‐retardant PP composites are investigated by limiting oxygen index (LOI), UL‐94 test, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and mechanical properties test. The results show that the PP/MTAPP/PA6 composites exhibit much better flame‐retardant performances than the PP/MTAPP composites. The higher LOI values and UL‐94 V‐2 of the PP/MTAPP composites with suitable amount of PA6 are obtained, which is attributed to the thick and compact char layer structure evidenced by SEM. The results from TGA and DSC demonstrate that the introduction of PA6 into PP/MTAPP composites has a great effect on the thermal stability and crystallization behaviors of the composites. Furthermore, the mechanical properties of PP/MTAPP/PA6 composites are also improved greatly due to the presence of PA6 as a charring agent. POLYM. ENG. SCI., 55:1355–1360, 2015. © 2015 Society of Plastics Engineers     

Component ratio effects of hyperbranched triazine compound and ammonium polyphosphate in flame‐retardant polypropylene composites

A hyperbranched derivative of triazine group (EA) was synthesized by elimination reaction between ethylenediamine and cyanuric chloride. The different‐mass‐ratio EA and ammonium polyphosphate (APP) were mixed and blended with polypropylene (PP) in a constant amount (25%) to prepare a series of EA/APP/PP composites. The component ratio effect of EA/APP on the flame‐retardant property of the EA/APP/PP composites was investigated using the limiting oxygen index (LOI), vertical burning (UL‐94), and cone calorimetry tests. Results indicated that the EA/APP/PP (7.50/17.50/75.00) composite with the appropriate EA/APP mass ratio had the highest LOI, UL94 V‐0 rating, lowest heat release rate, and highest residue yield. These results implied that the appropriate EA/APP mass ratio formed a better intumescent flame‐retardant system and adequately exerted their synergistic effects. Furthermore, average effective combustion heat values revealed that EA/APP flame retardant possessed the gaseous‐phase flame‐retardant effect on PP. Residues of the EA/APP/PP composites were also investigated by scanning electron microscopy, Fourier‐transform infrared, and X‐ray photoelectron spectroscopy. Results demonstrated that the appropriate EA/APP mass ratio can fully interact and lock more chemical constituents containing carbon and nitrogen in the residue, thereby resulting in the formation of a dense, compact, and intumescent char layer. This char layer exerted a condensed‐phase flame‐retardant effect on EA/APP/PP composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41006.     

硼酸锌在膨胀型阻燃聚丙烯中的协同阻燃机理研究

通过氧指数，热重分析（TGA）和扫描电子显微镜（SEM）研究了硼酸锌在膨胀型阻燃丙烯中的协同阻燃作用，硼酸锌的加入在用量低时可显著增加膨胀型阻燃聚丙烯（PP）的氧指数,而当用量超过一定值后，氧指数则急剧降低，TGA显示硼酸锌用量为2．5份时，500℃的剩焦量出现最大值。这与氧指数的数值非常吻合。扫描电子显微镜观察到硼酸锌用量为2．5份时，燃烧剩炭出现大泡孔结构，这种大泡孔具有非常薄的壁，为此，我们认为该体系的阻燃机理是聚磷酸铵分解后形成的玻璃状物与硼酸锌分解物形成一种乳液体系覆盖在燃烧物表面，该体系使聚磷酸铵分解产生的气泡稳定，形成有效的隔离层使阻燃性能得到提高。     

新型含氮阻燃剂/PEPA协同阻燃PP的性能

以三聚氯氰、对羟基苯甲酸甲酯、水合肼为原料经两步反应合成了一种新型含氮阻燃剂4,4′,4″–(1,3,5–三嗪–2,4,6–三取代)三氧三苯甲酰肼(TNTN),并通过核磁共振等对其进行表征。将合成的含氮阻燃剂TNTN与1–氧–4–羟甲基–2,6,7–三氧杂–1–磷杂双环[2.2.2]辛烷(PEPA)以不同配比制备膨胀型阻燃聚丙烯(PP)材料(IFR–PP)。通过极限氧指数(LOI)、垂直燃烧(UL–94)、热重(TG)分析、锥形量热(CCT)法以及扫描电子显微镜(SEM)对阻燃PP燃烧及热稳定性能进行表征。结果表明,IFR–PP同时具有良好的阻燃性及抗熔滴能力,当PEPA∶TNTN=2∶1时,UL–94达到V–0级,LOI值达到了33.7%,表现出良好的阻燃性能。TG测试表明:阻燃剂的加入使IFR–PP材料提前降解,同时提高了材料的成炭性能,当PEPA∶TNTN=5∶1时,600℃时IFR–PP材料的残炭量由空白样的0.07%提高到了20.6%。CCT测试表明:相对于纯PP,经阻燃剂改性后的PP热释放率和总热释放量均显著减少。SEM测试表明:不同配比阻燃剂的加入使PP在燃烧过程中形成膨胀、致密的炭层,很好地保护了下层材料,提高了PP材料的阻燃性能。     

Synthesis of a novel flame retardant containing phosphazene and triazine groups and its enhanced charring effect in poly(lactic acid) resin

A novel flame retardant heax‐[N,N′,N″‐tris‐(2‐amino‐ethyl)‐[1,3,5] triazine‐2,4,6‐triamine] cyclotriphosphazene (HTTCP) containing phosphazene and triazine groups was synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), solid‐state ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy. HTTCP was applied to PLA matrix. The results of thermal gravimetric analysis (TGA), the limited oxygen index (LOI), and cone calorimeter test indicated that the HTTCP enhanced the thermal stability and flame retardant properties of PLA. When the mass fraction of HTTCP was 25 wt %, the PLA composite acquired a LOI value of 25.2% and the lower pk‐HRR at 290 kW/m². The excellent flame retardancy of HTTCP was attributed to the group synergistic effect between phosphazene and triazine groups. However, when combined HTTCP with APP (the total amount remaining 25 wt %, the ratio of HTTP to APP are 1:1 and 1:2), high values of LOI (over 40%) and UL94 V‐0 rating without dripping reached simultaneously. Meanwhile, the heat release rate, total heat release and mass loss rate were all decreased dramatically. Scanning electron microscopy (SEM) demonstrated that HTTCP/APP system benefited to the formation of more intumescent, dense, compact char layer on the materials surface which could effectively prevent the underlying material from degradation during burning. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44660.