Fire and thermal properties of PA 66 resin treated with poly‐N‐aniline‐phenyl phosphamide as a flame retardant

In this study, a halogen‐free phosphorous‐nitrogen synergistic flame retardant, poly‐N‐aniline‐phenyl phosphamide (PDPPD), was synthesized. Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and elemental analysis data confirmed the structure of PDPPD. The essential FR PA66 was polymerized with PA66 pre‐polymer and PDPPD pre‐polymer, prepared from PDPPD and adipic acid. The limit oxygen index and UL‐94 test results of FR PA66 reached 28% and V‐0, respectively, when the contents of PDPPD pre‐polymer were 4.5 wt%. The thermo‐gravimetric and differential scanning calorimetry results demonstrated that the initial decomposition temperature of FR PA66 was 43 °C lower than that of pristine PA66 from 385 to 342 °C; however, the peak decomposition temperature was 36 °C higher than that of pure PA66 from 437 to 473 °C, when the contents of PDPPD pre‐polymer reached 4.5 wt%. Flame retardant mechanism was studied by cone calorimeter testing and SEM‐EDX, confirming that the heat release rate (HRR), total heat release (THR), and total smoke product (TSP) decreased slightly, and PDPPD followed the gas phase flame retardant mechanism. Copyright © 2016 John Wiley & Sons, Ltd.     

Preparation and properties of a novel flame retardant polyurethane quasi‐prepolymer for toughening phenolic foam

A novel phosphorus‐ and nitrogen‐containing polyurethane quasi‐prepolymer (PNPUQP) was synthesized and incorporated into phenolic foam (PF) in different ratios in order to improve the toughness. The structure of PNPUQP was confirmed by Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR). The effects of PNPUQP on the flame retardant properties, thermal stability and mechanical properties of modified PF were investigated. The results suggested that the addition of 3 wt % PNPUQP increased the toughness of PF and improved the flame retardancy. The investigation on the morphology of PF and modified PF by scanning electron microscope (SEM) certified the good toughness of the PNPUQP on PF. Additionally, the thermal properties of the foams were investigated by thermogravimetric analysis (TGA) under N₂ atmosphere. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42424.     

Synthesis,thermal stability,and flame retardancy of PA66, treated with dichlorophenylphsophine derivatives

Synthesis, thermal stability, and flame retardancy of PA66, treated with derivatives of dichlorophenylphosphine, are reported. With an aim to improve the thermal stability and flame retardancy of PA66, along with improving its consistency, several new derivatives of dichlorophenylphosphine, namely bis-(4-carboxyanilino) phenyl phosphamide (BNPO), N-benzoic acid-(ethyl-N-benzoic acid formamide) phosphamide (NENP), poly-N-aniline-phenyl phosphamide (DPPD), and bis-N-benzoguanamine-phenyl phosphamide (MCPO), were synthesized, which resulted in end amino or carboxyl. FTIR, ¹H NMR, MS, and elemental analysis confirmed the chemical structures of the synthesized flame retardants. Interestingly, thermal stabilities and flame retardancies of PA66 improved, however, the intrinsic viscosities ([η]) and viscosity average molecular weights (M_η) decreased with grafting of the flame retardants. Moreover, the consistency was overcome conformingly using SEM without interfacial effect.     

Effect of graphite on the flame retardancy and thermal conductivity of P‐N flame retarding PA6

In this article, a novel flame‐retardant polyamide 6 (PA6) was prepared by introducing a halogen‐free flame‐retardant (OP1314). Graphite was added as a flame‐retardant synergistic agent, and the flame retardancy was enhanced, especially the melt‐dripping was forbidden and for the formula of PA6/12 wt % OP1314/5 wt % graphite, UL94 V‐0 grade was reached. Meanwhile, the graphite is also an excellent thermal conductive filler and with the addition of 5 wt % graphite in the flame‐retardant PA6 mixtures, the thermal conductivity (λ) rose to 1.2 W/mK which was nearly three times higher than the flame‐retardant PA6. Due to the good flame retardancy and improved thermal conductivity, the material could be suitable for applications in electronic and electrical devices. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46559.     

New heat resistant nanocomposites reinforced silicate nanolayers containing triazine rings based on polyamide: Synthesis,characterization, and flame retardancy study

N¹,N¹′‐(6‐methoxy‐1,3,5‐triazine‐2,4‐diyl)dibenzene‐1,4‐diamine (MTDA) containing triazine ring structure was synthesized and characterized. A new, montmorillonite (Mt) modified by MTDA (MTDA‐Mt), was prepared by ion‐exchange of sodium montmorillonite (Na⁺‐Mt) with protonated form of MTDA. It was confirmed by Fourier transform infrared spectroscopy and X‐ray powder diffraction (XRD) techniques. The results of XRD indicated that MTDA had intercalated with Na⁺‐Mt. A new polyamide (PA) containing triazine ring was synthesized by direct polycondensation reaction of 4,4′‐(6‐methoxy‐1,3,5‐triazine‐2,4‐diyl)bis(azanediyl)dibenzoic acid and 4,4′‐diaminodiphenylether and characterized. PA/MTDA‐Mt nanocomposites containing 4 and 8 mass% of MTDA‐Mt were prepared via blending of MTDA‐Mt with the PA by solution intercalation technique in N‐methyl‐2‐pyrrolidone. The nanostructures and properties of the PA/MTDA‐Mt nanocomposites were investigated using different techniques. Transmission electron microscopy and XRD results revealed the good dispersion nano silicate layers in the polymer matrix. Thermal properties and flame retardancy of the resulting PA/MTDA‐Mt nanocomposites were investigated by thermal gravimetry analyses and microscale combustion calorimetry techniques. The results showed that the addition of MTDA‐Mt enhanced the flame retardancy of PA, reflecting the decrease in heat release rate from 111 W/g for PA to 91 and 77 W g⁻¹ for PA/MTDA‐Mt nanocomposites. POLYM. COMPOS., 188–198, 2016. © 2014 Society of Plastics Engineers     

The flame retardancy and mechanical properties of jute/polypropylene composites enhanced by ammonium polyphosphate/polypropylene powder

Surface flame retarded jute/polypropylene composites (J/P/A) were prepared via a modified strategy: the mixture of PP and APP powder was spread over the surface of jute/PP nonwoven felts, and then transformed into the flame retarded layer by the hot pressing process. The flame retardancy and thermal properties of composites were analyzed by limit oxygen index (LOI), horizontal burning rate (HBR), thermogravimetric analyses (TGA), and differential scanning calorimetry (DSC). We demonstrated that the flame retardancy and mechanical properties of composites was significantly improved compared with those obtained by presoaking the nonwoven fiber felts in flame retardant (FR) solvent before hot pressing. The mechanism of thermal degradation of jute fiber and flame‐retardant mechanism of composites were analyzed by Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), and scanning electron microscope (SEM). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43889.     

Aging studies on flame retardant treated lignocellulosic fibers

The study deals with chemical and flame retardant (FR) treatment of flax fabric. Sheets of flax fabric were subjected to chemical treatments using NaOH and silane coupling agents. A phosphate‐based flame retardant (DAP) was also applied to improve the flammability of the fabric. The effects of the chemical treatments and FR treatments on flax fabric were investigated using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and vertical flame resistance test. Aging studies were carried out by exposing the samples in an environmental chamber at specified conditions for two weeks. The mechanical properties of the fabric, before and after environmental aging, were investigated. Flammability of flax fabric was improved after FR treatment. Thermal studies revealed a shift of decomposition temperature to lower temperatures and an increase in char residue after FR treatment. Despite treatment of the fabric with NaOH and silane, the tensile strength of FR‐treated flax fabric declined by more than 90% after aging for two weeks at 90 °C and 50% RH. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44175.     

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.     

高含量玻璃纤维增强阻燃聚酰胺材料的制备与性能

采用双螺杆挤出机制备了聚酰胺6(PA6)/50%（质量分数,下同）玻璃纤维（GF）、PA66/50%GF、PA56/50%GF 3种高含量GF增强阻燃PA复合材料,对比研究了红磷、溴系、磷氮3种阻燃体系下复合材料的力学性能、阻燃性能和激光打标性能。结果表明,不同阻燃体系对复合材料的力学性能有明显影响,吸水平衡后,PA66复合材料的力学性能保持率最高;PA56复合材料在3种阻燃体系中均表现出比PA6、PA66复合材料更好的阻燃性能;红外激光和紫外激光的打标效果存在明显不同,而在阻燃体系和激光光源相同的条件下,PA6、PA66和PA56 3种PA复合材料的激光打标效果没有明显差异。     

Flame retarding mechanism of Polyamide 6 with phosphorus‐nitrogen flame retardant and DOPO derivatives

A novel flame‐retardant composite was prepared by introducing a phosphorus‐nitrogen flame retardant and DOPO‐SiO₂ into PA6. DOPO‐SiO₂ was synthesized successfully in a one‐step process. PA6/OP1314/DOPO‐SiO₂ achieved a UL 94 V‐0 rating with an LOI value of 31%. The maximum mass loss rate of decomposition decreased significantly and char residue increased to 11.6 wt % compared with that of pure PA6. The compacted and dense char was formed due to the combination of the P‐N flame retardant and DOPO‐SiO₂. The complex viscosity of PA6/OP1314/DOPO‐SiO₂ increased considerably which tend to prevent the dripping phenomenon. The flame‐retardant mechanism of PA6/OP1314/DOPO‐SiO₂ was also investigated by Fourier transform infrared spectroscopy FTIR at different temperatures and the pyrolysis products were investigated by pyrolysis gas chromatography/ mass spectrum (Py‐GC/MS). It was assumed that DOPO‐SiO₂ and the hypophosphite of OP1314 possess excellent flame retardancy during the gaseous phase. Meanwhile, melamine and phosphate reacted with the pyrolytic products of PA6 to protect the matrix during the condensed phase. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42932.     

Effect of type of substitution in 4,4′‐bis‐(diaminodiphenyl) methane hardener on cure kinetics,mechanical, and flame retardant properties of tetrafunctional epoxy resins

The nature of the substituent in 4,4′‐bis‐(diaminodiphenyl) methane (DDM) hardener on the cure kinetics, mechanical, and flame retardant properties of N,N,N′,N′‐tetraglycidyl diaminodiphenyl methane (TGDDM) resin is investigated in comparison with unsubstituted DDM and widely used 4,4′‐bis‐(diaminodiphenyl) sulfone hardeners. Dynamic differential scanning calorimetry (DSC) and cure rheology studies showed that the substitution decreased the reactivity of the amine. An electron‐withdrawing chlorine substituent was found to be more effective than an electron‐releasing methyl group in reducing the amine reactivity. Substituted and unsubstituted DDM hardeners showed two peaks in their DSC thermograms that were due to steric hindrance in the former and deficiency of amine in the latter. Substitution showed its effect on the mechanical properties and glass‐transition temperature. The flexural modulus was increased; however, the Izod impact and glass‐transition temperature were decreased in substituted amine systems. The limiting oxygen index results showed higher flame retardancy in the chlorine substituted hardener system compared to other hardener systems that were studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 480–491, 2006     

An effective intumescent flame retardancy of LDPE induced by the combination of APP and CNCO‐HA

A char‐forming agent poly(4,6‐dichloro‐N‐hydroxyethyl?1,3,5‐triazin‐2‐amine‐1,6‐diaminohexane) (CNCO‐HA) containing triazine rings was chosen for improving the flame retardant of low density polyethylene (LDPE). The synergistic effect of CNCO‐HA and Ammonium polyphosphate (APP) on the flame retardancy and char‐forming behavior of LDPE were investigated. The limited oxygen index (LOI) and vertical burning test (UL‐94) results indicated the optimal weight ratio of APP to CNCO‐HA was 3:1, and the LOI value of composite reached 31.0% with 30% intumescent flame retardant (IFR) loading. The cone calorimeter test analysis revealed that IFR presented excellent char forming and smoke suppression ability, and resulted in the efficient decrease of combustibility parameters. The thermogravimetric analysis results demonstrated that IFR reduced the thermal degradation rate at main stage of degradation. Scanning electron microscopy observed that IFR promoted to form a compact and continuous intumescent char layer. The Laser Raman spectroscopy spectra showed that larger graphitization degree was formed to enhance the strength of char, and Fourier transform infrared results presented that P‐O‐C and P‐O‐P structures in the residue char were formed to improve shield performance of the char layer to obtain better flame retardant properties of the composite. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43950.     

In situ polymerization of flame retardant modification polyamide 6,6 with 2-carboxy ethyl (phenyl) phosphinic acid

A novel halogen-free flame retardant copolyamide 6,6 (FR-PA66) was prepared successfully by in situ polymerizing with adipic acid hexamethylene salt and 2-carboxy ethyl (phenyl) phosphinic acid (CEPPA). The elemental composition and chemical structure of FR-PA66 were characterized by energy dispersive X-ray spectroscopy, Fourier transform infrared spectrometer and ¹³C Nuclear magnetic resonance spectrometer. The flame retardancy, thermal stability, and morphology of char residues were also investigated by the limiting oxygen index (LOI), UL 94 test, thermogravimetric analysis, and scanning electron microscopy. The results showed that FR-PA66 samples had much better flame retardancy and char formation ability than pure PA66 after the flame retardant modification. The LOI values were increased from 24.0 to 28.0% by adding 6 wt % of CEPPA and all FR-PA66 samples were rated as V-0 rating in UL-94 test. Furthermore, the thermal stability analysis indicated that in situ polymerization with CEPPA effectively decreased the initial decomposition temperature and increased the amount of char residue. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48687.     

The flame‐retardant properties and mechanisms of poly(ethylene terephthalate)/hexakis (para‐allyloxyphenoxy) cyclotriphosphazene systems

Para‐allyl ether phenol derivative of cyclophosphazene (PACP) was prepared and used as a filler to modify the flame‐retardant properties of poly(ethylene terephthalate) (PET) by melting‐blending. The mechanism of flame‐retardant was discussed and the influences of flame‐retardant contents to the mechanical properties were studied. The results revealed that the incorporation of only 5 phpp PACP (0.37 wt % phosphorus containing) into PET matrix can distinctly increase the flame retardancy of PET/PACP composition, and it has a little effect on the mechanical properties of PET. The high flame‐retardant performance of PET/PACP composite was attributed to the combination of condensed‐phase flame retardant and gas‐phase flame retardant. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42711.     

A phosphorus‐containing phenolic derivative and its application in benzoxazine resins: Curing behavior,thermal, and flammability properties

In this work, flame‐retardant benzoxazine resins were prepared by copolymerization of bisphenol A based benzoxazine (BA‐a) and a phosphorous‐containing phenolic derivative (DOPO‐HPM). The curing behavior, thermal stability, and flame resistance of BA‐a/DOPO‐HPM composites were studied by differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), limited oxygen index (LOI) measurement, UL94 test, and cone calorimeter. The DSC results indicated that DOPO‐HPM catalyzed the curing reaction because of its acidity. The TGA results revealed that the BA‐a/DOPO‐HPM thermosets possessed higher decomposition temperatures (T_5%) and char yields than that of BA‐a. The combustion tests indicated that the flame retardant properties of BA‐a/DOPO‐HPM thermosets were enhanced. The BA‐a/DOPO‐HPM‐20 sample acquired the highest LOI value of 32.6% and UL94 V‐0 rating. Moreover, the average of heat release rate (av‐HRR), peak of heat release rate (pk‐HRR), average of effective heat of combustion (av‐EHC) and total heat release (THR) of BA‐a/DOPO‐HPM‐20 were decreased by 24.6%, 53.1%, 14.9%, and 22.1%, respectively, compared with BA‐a. The attractive performance of BA‐a/DOPO‐HPM blends was attributed to the molecular structure of DOPO‐HPM composed of DOPO group with excellent flame‐retardant effect and phenolic hydroxyl group with catalysis. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43403.     

Preparation of alginate flame retardant containing P and Si and its flame retardancy in epoxy resin

In the present paper, a novel biomass flame retardant based on alginic acid was synthesized through chemical combination with a reactive P–Si compound. Compared with alginates, the modified alginate showed obviously increased thermal stability and water resisting property, as well as better compatibility with epoxy resin, which can satisfy the requirements of a flame‐retardant additive in the polymer. The flame‐retardant properties were evaluated by vertical burning tests, limiting oxygen index, and microscale combustion calorimetry. Due to the self‐charring capacity of alginate combined with the charring catalyst from P and the charring reinforcer from Si, the modified alginate exhibited much better flame retardancy, taking advantage of the formation of a more continuous, denser, and strengthened char layer than either individual alginate or P–Si flame retardant. The corresponding flame‐retardant mechanisms were investigated and discussed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45552.     

微胶囊化红磷阻燃剂的制备及其在玻纤增强尼龙66中的应用

为克服红磷直接应用于玻纤增强尼龙66中的缺点,研究了用原位聚合法制备微胶囊红磷的工艺,测试了样品的吸湿性以及表面包覆性能,并研究了其用于玻纤增强尼龙66的阻燃性能和力学性能。结果表明,制得的微胶囊化红磷应用于玻纤增强尼龙66中,不仅具有优良的阻燃性能(FV 0级),而且力学性能比单独应用红磷有所提高,加工工艺性能有较大幅度的提高。     

Effect of zinc oxide on properties of phenolic foams/halogen‐free flame retardant system

A halogen‐free flame retardant system consisting of ammonium polyphosphate (APP) as an acid source, blowing agent, pentaerythritol (PER) as a carbonific agent and zinc oxide (ZnO) as a synergistic agent, was used in this work to enhance flame retardancy of phenolic foams. ZnO was incorporated into flame retardant formulation at different concentrations to investigate the flammability of flame retardant composite phenolic foams (FRCPFs). The synergistic effects of ZnO on FRCPFs were evaluated by limited oxygen index (LOI), thermogravimetric analysis (TGA), cone calorimeter tests, and images of residues. Results showed that the flame retardant significantly increased the LOI of FRCPFs. Compared with PF, heat release rate (HRR), total heat release (THR), effective heat of combustion (EHC), production or yield of carbon monoxide (COP or COY) and Oxygen consumption (O₂C) of FRCPFs all remarkably decreased. However specific extinction area (SEA) and total smoke release (TSR) significantly increased, which agreed with the gas‐phase flame retardancy mechanism of the flame retardant system. The results indicated that FRCPFs have excellent fire‐retardant performance and less smoke release. And the bending and compression strength were decreased gradually with the increase of ZnO. The comprehensive properties of FRCPFs were better when the amount of ZnO was 1～1.5%. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42730.     

Properties of poly(vinyl chloride) incorporated with a novel soybean oil based secondary plasticizer containing a flame retardant group

A novel bio‐based plasticizer containing flame retardant groups based on soybean oil (SOPE) was synthesized from epoxidized soybean oil (ESO) and diethyl phosphate through a ring‐opening reaction. PVC blends plasticized with ESO and SOPE were prepared, respectively. Properties including rheological behavior, thermal stability, flame retardant performance, mechanical properties of PVC plasticized with ESO and SOPE were carefully studied. The results showed that the plasticized PVC blends indicated better compatibility, thermal, and mechanical properties. As a novel bio‐based plasticizer containing flame retardant groups, the TGA data indicated that the thermal degradation temperature of PVC blends plasticized with SOPE could reach to 275.5°C. LOI tests and SEM indicated that the LOI value of PVC blends could increase from 24.2 to 33.6%, the flame retardant performance of SOPE was put into effect by promoting polymer carbonization and forming a consolidated and thick flame retardant coating quickly, which is effective to prohibit the heat flux and air incursion. The enhancement in flame retardancy will expand the application range of PVC materials plasticized with SOPE. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42111.     

Improvement in flame retardancy of polyurethane dispersions by newer reactive flame retardant

A novel phosphorus containing reactive flame retardant was synthesized and incorporated successfully in polyurethane backbone to obtain flame retardant aqueous polyurethane dispersions (FRPUDs). The reactive flame retardant compound was synthesized by using phosphorus oxychloride (1 mole) and N-methylaminoethanol (3 mole). The structure of synthesized phosphorus containing triol was confirmed by FTIR, ¹H NMR and ³¹P NMR spectrometry. Further, polyurethane prepolymer was modified with phosphorus containing triol compound in various amounts (30, 40 and 50% on equivalent basis) and FRPUDs were prepared. PUD films were applied on wood and mild steel panels and air dried. It was then characterized for mechanical, chemical, thermal and flame retardant properties. It was observed that all FRPUDs exhibited good mechanical properties and improved flame retardancy as compared to the conventional one. The maximum limiting oxygen index (LOI) value of 37 was obtained for FRPUD containing 0.8 mass% of phosphorus and 1 mass% of nitrogen. The flame retardancy was greatly depending on the phosphorus content and increased with increase in phosphorus content.