The flame retardant group‐synergistic‐effect of a phosphaphenanthrene and triazine double‐group compound in epoxy resin

A flame retardant tri‐(phosphaphenanthrene‐(hydroxyl‐methylene)‐phenoxyl)‐1, 3, 5‐triazine (Trif‐DOPO) and its control samples are incorporated into diglycidyl ether of bisphenol‐A (DGEBA) and 4, 4′‐diamino‐diphenyl sulfone (DDS) to prepare flame retardant thermosets, respectively. According to the results of limited oxygen index (LOI), UL94 vertical burning test and cone calorimeter test, the Trif‐DOPO/DGEBA/DDS thermoset with 1.2 wt % phosphorus possesses the LOI value of 36% and UL94 V‐0 flammability rating, and Trif‐DOPO can decrease the peak of heat release rate (pk‐HRR) and reduce the total heat release (THR) of thermosets. All these prove better flame retardant performance of Trif‐DOPO than that of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide(DOPO). The residue photos of thermosets after cone calorimetry test disclose that Trif‐DOPO can promote the formation of thick and tough melting char layer for combined action of the flame retardant groups of Trif‐DOPO. The results from thermo gravimetric analysis (TGA) and pyrolysis‐gas chromatography‐mass spectrometry(Py‐GC/MS) show that the groups in Trif‐DOPO can be decomposed and produce PO₂ fragments, phosphaphenanthrene and phenoxy fragments, which can jointly quench the free radical chain reaction during combustion. Therefore, the excellent flame retardancy of Trif‐DOPO is attributed to its flame retardant group‐synergic‐effect. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39709.     

Synthesis and properties of a novel phosphorous‐containing flame‐retardant hardener for epoxy resin

An aryl phosphinate dianhydride 1,4‐bis(phthalic anhydride‐4‐carbonyl)‐2‐(6‐oxido‐6H‐dibenz[c,e][1,2]‐oxaphosphorin‐6‐yl)‐phenylene ester (BPAODOPE) was synthesized and its structure was identified by FTIR and ¹H‐NMR. BPAODOPE was used as hardener and flame retardant for preparing halogen‐free flame‐retarded epoxy resins when coupled with another curing agent. Thermal stability, morphologies of char layer, flame resistance and mechanical properties of flame‐retarded epoxy resins were investigated by thermogravimetric analysis, SEM, limiting oxygen index (LOI), UL‐94 test, tensile, and charpy impact test. The results showed that the novel BPAODOPE had a better flame resistance, the flame resistance and char yield of flame‐retarded epoxy resins increased with an increase of phosphorus content, tensile strength and impact strength of samples gradually decreased with the addition of BPAODOPE. The flame‐retarded sample with phosphorus contents of 1.75% showed best combination properties, LOI value was 29.3, and the vertical burning test reached UL‐94 V‐0 level, tensile strength and impact strength were 30.78 MPa and 3.53 kJ/m², respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synergistic flame‐retardant effect of phosphaphenanthrene derivative and aluminum diethylphosphinate in glass fiber reinforced polyamide 66

The synergistic flame‐retardant (FR) effect of 1,1′‐bis(4‐hydroxyphenyl)‐metheylene‐bis(9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide‐2‐hydroxypropan‐1‐yl) (DPOH) and aluminum diethylphosphinate (AlPi) composites on glass fiber reinforced polyamide 66 (PA) was investigated by limiting oxygen index (LOI) tests, vertical burning (UL94) tests, and cone calorimeter tests. DPOH/AlPi system with 1:1 mass ratio increased UL94 ratings, suppressed heat release rate and increased residue yields of PA composites, and DPOH/AlPi system also imposed high LOI values and lower total heat release values to PA composites. All these results verified excellent synergistic FR effect between DPOH and AlPi. The reason of DPOH/AlPi system with higher flame‐retardant efficiency was caused by the quenching effect as good as that of DPOH and also by the higher charring effect than that of AlPi. DPOH/AlPi system possesses good flame retardancy in gas phase and also the strengthened FR effect in condensed phase compared with DPOH and AlPi alone, which led to excellent synergistic FR effect between the two components DPOH and AlPi. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45126.     

Synthesis of a novel,multifunctional inorganic curing agent and its effect on the flame‐retardant and mechanical properties of intrinsically flame retardant epoxy resin

Traditional curing agents have only a single property, while traditional synthetic organic flame‐retardant hardeners often show poor tolerance to oxidants, strongly acidic or alkaline reagents, and organic solvents and have toxicity problems. Here, a novel and multifunctional flame‐retardant curing agent of the inorganic substrate multifunctional curing agent of the inorganic substrate (FCIN) was proposed first and successfully prepared, and then an intrinsically flame‐retardant epoxy resin (EP) was prepared by covalently incorporating FCIN nanoparticles (FCINs) into the EP. The curing behavior of the FCINs was investigated, showing that FCIN/EP expresses a higher global activation energy than tetraethylenepentamine (TEPA)/EP and that the FCINs had strong interfacial adhesion to the EP matrix. Additionally, the FCINs were well dispersed and provided a remarkable improvement in mechanical and flame‐retardant properties of the intrinsically flame‐retardant EP. With the incorporation of 9 wt % FCINs into the EP, dramatic enhancements in the strength, modulus under bending, and toughness (～36%, ～109%, and ～586%, respectively) were observed, along with 85.2%, 46.4%, 98.3%, and 77.26% decreases in the peak heat release rate, total heat release, smoke production rate peak, and total smoke production, respectively, with respect to that of TEPA/EP. The mechanisms of its flame‐retardant, smoke‐suppression, and failure behaviors were investigated. The development of this unconventional, multifunctional flame‐retardant curing agent based on an inorganic substrate showed promise for enabling the preparation of a variety of new high‐performance materials (such as intrinsically flame‐retardant EP and functional modified polyesters). © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46410.     

Preparation and investigation of flame‐retardant epoxy resin modified with a novel halogen‐free flame retardant containing phosphaphenanthrene,triazine‐trione,and organoboron units

In this article, a novel flame retardant (coded as BNP) was successfully synthesized through the addition reaction between triglycidyl isocyanurate, 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide and phenylboronic acid. BNP was blended with diglycidyl ether of bisphenol‐A to prepare flame‐retardant epoxy resin (EP). Thermal properties, flame retardancy, and combustion behavior of the cured EP were studied by thermogravimetric analysis, limited oxygen index (LOI) measurement, UL94 vertical burning test, and cone calorimeter test. The results indicated that the flame retardancy and smoke suppressing properties of EP/BNP thermosets were significantly enhanced. The LOI value of EP/BNP‐3 thermoset was increased to 32.5% and the sample achieved UL94 V‐0 rating. Compared with the neat EP sample, the peak of heat release rate, average of heat release rate, total heat release, and total smoke production of EP/BNP thermosets were decreased by 58.2%–66.9%, 27.1%–37.9%, 25.8%–41.8%, and 21.3%–41.7%, respectively. The char yields of EP/BNP thermosets were increased by 46.8%–88.4%. The BNP decomposed to produce free radicals with quenching effect and enhanced the charring ability of EP matrix. The multifunctional groups of BNP with flame retardant effects in both gaseous and condensed phases were responsible for the excellent flame retardancy of the EP/BNP thermosets. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45291.     

Synthesis of phosphorus‐containing flame‐retardant antistatic copolymers and their applications in polypropylene

By adjusting the molar ratios of antistatic monomer of octyl phenol ethylene oxide acrylate (denoted as AS), rigid monomer of methyl methacrylate (denoted as MMA), and flame‐retardant monomer of 2‐(phosphoryloxymethyl oxyethylene) acrylate (denoted as FR), a series of flame‐retardant antistatic copolymers poly (octyl phenol ethylene oxide acrylate‐co‐methyl methacrylate‐co‐phosphoryloxymethyl oxyethylene acrylate) (donated as AMF) were synthesized through radical polymerization. Among the obtained copolymers, two copolymers, AMF162 (the feed molar ratio of AS, MMA, and FR as 1 : 6 : 2) and AMF1104 (the feed molar ratio of AS, MMA, and FR as 1 : 10 : 4) with different concentrations were added into polypropylene (PP) to prepare PP‐AMF162 and PP‐AMF1104 series of composites. The thermal stability, limiting oxygen index, the antistatic property, and mechanical properties of PP composites were tested and analyzed. PP‐AMF162 series composites have excellent antistatic effect. When the AMF162 content was equal to or <15 wt %, the impact strength of PP‐AMF162 composites was higher than that of pure PP. The results indicated that copolymer AMF162 was a suitable flame‐retardant and antistatic additive for PP. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41677.     

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.     

Improved flame retardancy by synergy between cyclotetrasiloxane and phosphaphenanthrene/triazine compounds in epoxy thermoset

A siloxane compound (MVC) and a bi‐group phosphaphenanthrene/triazine compound (TGD) were employed in epoxy thermosets to explore high‐efficiency flame retardant systems. With only 1 wt% MVC and 3 wt% TGD, an epoxy thermoset passed UL 94 V‐0 rating test and achieved a limiting oxygen index value of 34.0%, exhibiting an excellent flame retardant effect. The MVC/TGD system not only decreased the peak value of heat release rate and effective heat of combustion but also imparted an improved charring ability to thermosets, thereby outstandingly reducing the flammability of 1%MVC/3%TGD/EP. Compared with the fire performance of 4%TGD/EP and 4%MVC/EP, the MVC/TGD system showed an obvious flame retardant synergistic effect, mainly depending on the general improvement of flame inhibition, charring and barrier effects of the thermoset during combustion. Evolved gas analysis combined with condensed‐phase pyrolysis product analysis jointly revealed the details of the changed pyrolysis mode. © 2017 Society of Chemical Industry     

Synergistic effect of expandable graphite and aluminum hypophosphite on flame‐retardant properties of rigid polyurethane foam

A series of flame retarding rigid polyurethane foam (RPUF) composites based on expandable graphite (EG) and aluminum hypophosphite (AHP) were prepared by the one‐pot method. The properties were characterized by limiting oxygen index (LOI) test, cone calorimeter test, thermogravimetric analysis (TGA), real‐time Fourier transform‐infrared spectra (RT‐FT‐IR), X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), etc. The results indicate that both EG and AHP could enhance the flame retardency of RPUF composites. Besides, the flame retardant effect of EG was better than that of AHP. The results also show that partial substitution of EG with AHP could improve the flame retardency of RPUF, and EG and AHP presented an excellent synergistic effect on flame retardancy. What is more, compared with RPUF/20EG and RPUF/20AHP, the heat release rate (HRR) and total heat release (THR) of RPUF/15EG/5AHP were lower.TGA results indicate that partial substitution of EG with AHP could improve the char residue which provided better flame retardancy for RPUF composites. The thermal degradation process of RPUF composites and the chemical component of the char residue were investigated by RT‐FT‐IR and XPS. And the results prove that RPUF/15EG/5AHP had higher heat resistance in the later stage. Compared with the RPUF composites filled with EG, a better cell structure and mechanical properties were observed with the substitution of AHP for part of EG. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42842.     

Synergistic effects of zinc oxide in montmorillonite flame‐retardant polystyrene nanocomposites

In this study, two‐dimensional organic montmorillonite (OMMT) and one‐dimensional needlelike ZnO were used as flame retardants of polystyrene (PS). Polystyrene/organic montmorillonite (PMT) and polystyrene/organic montmorillonite/zinc oxide nanocomposites (PMZs) with different weight ratios were prepared by melt intercalation. Information on the morphologies and structures of the PS nanocomposites was obtained with Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results indicate that a mixed exfoliated–intercalated structure was observed in the PMT and PMZs. Dynamic mechanical thermal analysis showed that both the storage modulus and glass‐transition temperature values of the PMT and PMZs were significantly improved compared with those of the neat PS. The mechanical property tests showed that the bending modulus values of both PM5 (PS/OMMT weight ratio = 95:5) and PMZs increased compared with that of pristine PS. PMZ1 (PS/OMMT/ZnO weight ratio = 94:5:1) provided no decrease in the tensile strength in comparison with PS. A synergistic effect was observed between OMMT and ZnO; this resulted in improvements in the flame retardancy and dynamic mechanical properties in the PMZs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43047.     

Pyrolysis of epoxy resins and fire behavior of epoxy resin composites flame‐retarded with 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide additives

The pyrolysis of an epoxy resin and the fire behavior of corresponding carbon fiber‐reinforced composites, both flame‐retarded with either 10‐ethyl‐9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene 10‐oxide or 1,3,5‐tris[2‐(9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene 10‐oxide‐10‐)ethyl]1, 3,5‐triazine‐2,4,6(1H,3H,5H)‐trione, are investigated. The different fire retardancy mechanisms are discussed, and their influence on the fire properties assessed, in particular for flammability (limiting oxygen index, UL 94) and developing fires (cone calorimeter with different external heat fluxes of 35, 50, and 70 kW m^?2). Adding the flame retardants containing 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide affects the fire behavior by both condensed phase and gas phase mechanisms. Interactions between the additives and the epoxy resin result in a change in the decomposition pathways and an increased char formation. The release of phosphorous products results in significant flame inhibition. The fire properties achieved are thus interesting with respect to industrial exploration. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2260–2269, 2007     

Flame‐retardant,glass‐fabric‐reinforced epoxy resin laminates fabricated through a gradient distribution mode

In general, epoxy resin (EP) glue mixed with a high content of flame retardants is used to coat glass fabrics layer by layer to prepare fire‐retardant printed circuit boards (PCBs). However, the addition of the flame retardants not only increases the cost but also greatly deteriorates the processability and mechanical properties of the PCBs. In this study, a gradient distribution mode of composite flame retardants was designed and applied in EP‐based PCB composites. Unlike the traditional uniform distribution mode, in which flame retardants are evenly distributed in every resin layer, the gradient mode concentrates a higher content of the flame retardants on the surface layer, and the concentrations are gradually reduced along the thickness. In this way, the surface resin can quickly form a condensed charring barrier to hold back fire; this effectively protects the underlying resin, which has lower contents of flame retardant. The results of this study show that PCB prepared by the gradient mode obtained satisfactory flame retardance (a UL94 V‐0 rating) with only a 3.5 wt % total amount of flame retardant; this value was much lower than that (6.3 wt %) of composites featuring a uniform distribution. Additionally, the gradient mode also maintained the mechanical properties of PCB better. The tensile, impact, and flexural strengths of the gradient distribution system were obviously higher than those of the uniform distribution one with the same content of flame retardant. On the basis of the mode, a more economic and efficient technology was developed to manufacture flame‐retardant layered PCB. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44369.     

Melamine polyphosphate/silicon‐modified phenolic resin flame retardant glass fiber reinforced polyamide‐6

The halogen‐free flame retardance of glass fiber reinforced polyamide‐6 (PA6) is an everlastingly challenge due to well‐known wick effect. In this research, a novel system composed of a nitrogen–phosphorous flame retardant, melamine polyphosphate combined with a macromolecular charring agent, silicon‐modified phenolic resin (SPR), was employed to flame‐retard glass fiber reinforced PA6. It exhibited obvious synergistic effect between the two components at a proper ratio range. The flame retardance of the composites can be remarkably improved due to the increased amount and improved thermal stability of the produced char. The flame resistance tests indicated that the synergism system with an optimized ratio achieved V0 (1.6 mm) rating of UL94, 25.2% of Limited Oxygen Index, and only 338.2 W/g of the heat release peak rate. The corresponding synergistic mechanisms were investigated by the characterizations including the thermal gravimetric analysis, carbonation test, and the char morphology observation. It confirmed that the introduced SPR could accelerate the carbonation of PA6 resin, which was in favor of the construction of denser and more continuous charring structure. In addition, the flame retardant materials also indicated the acceptable mechanical properties, showing the advantages in the overall performance. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

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‐retardant properties and mechanisms of epoxy thermosets modified with two phosphorus‐containing phenolic amines

Two phosphorus‐containing phenolic amines, a 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO)‐based derivative (DAP) by covalently bonding DOPO and imine (SB) obtained from the condensation of p‐phenylenediamine with salicylaldehyde, and its analog (AP) via the addition reaction between diethyl phosphite and SB, were used to prepare flame‐retardant epoxy resins. The burning behaviors and dynamic mechanical properties of epoxy thermosets were studied by limited oxygen index (LOI) measurement, UL‐94 test, and dynamic mechanical analysis. The flame‐retardant mechanisms of modified thermosets were investigated by thermogravimetric analysis, Py‐GC/MS, Fourier transform infrared, SEM, elemental analysis, and laser Raman spectroscopy. The results revealed that epoxy thermoset modified with DAP displayed the blowing‐out effect during UL‐94 test. With the incorporation of 10 wt % DAP, the modified thermoset showed an LOI value of 36.1% and V‐0 rating in UL‐94 test. The flame‐retardant mechanism was ascribed to the quenching and diluting effect in the gas phase and the formation of phosphorus‐rich char layers in the condensed phase. However, the thermoset modified with 10 wt % AP only showed an LOI value of 25.7% and no rating in UL‐94 test, which was possibly ascribed to the mismatching of charring process with gas emission process during combustion. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43953.     

Transparent epoxy resin material with excellent fire retardancy enabled by a P/N/S containing flame retardant

An epoxy resin (EP) with excellent fire retardancy, good transparency, and satisfactory thermal stability has been obtained by introducing a new N/P/S containing flame retardant (HBD) into EP composites. When the phosphorus content was 0.48 wt%, EP/HBD reached V-0 rating with the limiting oxygen index of 33.5%. The cone calorimeter test (CC) indicated that the incorporation of HBD resulted in 1.5 times increase in ignition time, a 50% decrease in the maximum of heat release rates, 40% reduction of total heat release, and 50.7% decrease in total smoke production compared with EP. Besides, the fire-resistant behavior of EP/8% HBD is much better than the EP materials modified by similar P/N/S flame retardants reported in literature. The fire-retardant mechanism of HBD on EP was also analyzed by Raman, scanning electron microscope, Py-GC/MS, and Fourier transform infrared spectroscopy. The results show that HBD plays an important role in the formation of a dense intumescent carbon layer and gas phase quenching.     

An intrinsic flame retardant epoxy resin with high transparency and strengthened mechanical property

In order to search for multifunctional epoxy thermosets (EP) with low flammability, high transparency and satisfied mechanical performance, DOPO-based phosphonate ammonium salt (DOA) was synthesized from 10-hydroxy-9,10-dihydro-9-oza-10-phosphaphenanthrene-10-oxide (DOPO-OH) and 2-amino-2-methyl-1,3-propanediol (AMPD). Under the influence of DOA, the flame-retardant and mechanical performances of the resulting EP were obviously improved. On account of the enhanced interaction and the incorporated flexible fragments in epoxy macromolecular chains, the tensile strength, elongation at break, and impact toughness of EP/5.0 wt% DOA significantly increased from 65.4 ± 1.2 MPa, 6.7 ± 0.6%, and 12.1 ± 1.3 kJ m⁻² of EP to 81.4 ± 2.8 MPa, 10.6 ± 0.5%, and 18.0 ± 1.1 kJ m⁻², respectively. In the presence of DOA, the limiting oxygen index (LOI) value of EP/5.0 wt% DOA increased to 35.5% and it passed the underwriter laboratories-94 vertical burning tests (UL-94 V) and got a V-1 rating. Moreover, the peak value of heat release rate (PHRR) was decreased by 38.0%. The analyses of char residues and volatile products showed that the activities of DOA on reducing the flammability of EP were ascribed to the protective effect of the char, the release of incombustible gases, and the radical-capture action of phosphorus-containing free radicals. Moreover, the modified epoxy thermosets still retained a high transparency.     

Microencapsulation of intumescent flame‐retardant agent: Application to flame‐retardant natural rubber composite

The first part of this investigation focused on the synthesis and characterization of a microencapsulated intumescent flame retardant (MIFR) agent. Two steps were used in the synthesis process. The structure was characterized by scanning electron microscopy, thermogravimetric anaylysis, and Fourier transform infrared spectroscopy. The addition of this MIFR agent into natural rubber (NR) led to an improvement in its physicomechanical and flame‐retardant (FR) properties. The second part focused on the evaluation of such characteristics as cure characteristics, FR property, tensile properties, abrasion resistance, and dynamic mechanical analysis of MIFR filled NR composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1828–1838, 2007     

Excellent role of Cu2O on fire safety of epoxy resin with ammonium polyphosphate based on the construction of self-intumescent flame retardant system

This work reports an effective self-intumescent flame retardant system for epoxy resin (EP) based on the remarkable synergistic effect between Cu₂O and ammonium polyphosphate (APP). The effect of Cu₂O/APP on improving EP's fire performance was evaluated by limited oxygen index (LOI), UL-94, and cone calorimeter test. The optimal mass ratio of Cu₂O: APP was shown to be 2:8. With 15 wt% total flame retardant loading, the EP with optimum Cu₂O/APP formulation reached V-0 classification and high LOI (33.5%), while the EP with APP only got NR and low LOI (26.5%). Additionally, the pHRR, total heat release, total smoke production, CO production of the EP with optimum Cu₂O/APP formulation were primarily decreased. All the improvements were ascribed to the formation of the self-intumescent char layer of EP resulted from the catalyzing effect of Cu₂O for char formation and CO to CO₂ conversion. These findings will consolidate approaches for conferring flame retardancy to flammable polymers or their blends.     

Synthesis of a novel curing agent containing organophosphorus and its application in flame‐retarded epoxy resins

A novel amine‐terminated and organophosphorus‐containing compound m‐aminophenylene phenyl phosphine oxide oligomer (APPPOO) was synthesized and used as curing and flame‐retarding agent for epoxy resins. Its chemical structure was characterized by Fourier transform infrared (FTIR) spectroscopy, ¹H nuclear magnetic resonance (¹H NMR), ¹³C nuclear magnetic resonance, and ³¹P nuclear magnetic resonance. The flame‐retardant properties, combusting performances, and thermal degradation behaviors of the cured epoxy resins were investigated by limiting oxygen index (LOI), vertical burning test (UL‐94), cone calorimeter test, and thermogravimetric analysis. The EPO/APPPOO thermosets passed V‐1 rating with the thickness of 3.0 mm and the LOI value reached 34.8%. The thermosets could pass V‐2 rating when the thickness of the samples was 1.6 mm. The cone calorimeter test demonstrated that the parameters of EPO/APPPOO thermosets including heat release rate and total heat release significantly decreased compared with EPO/PDA thermosets. Scanning electron microscopy revealed that the incorporation of APPPOO into epoxy resins obviously accelerated the formation of the compact and stronger char layer to improve flame‐retardant properties of the cured epoxy resins during combustion. The mechanical properties and water resistance of the cured epoxy resins were also measured. After the water‐resistance test, EPO/APPPOO thermosets still remained excellent flame retardant and the water uptake was only 0.4%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41159.