Flame‐retardant materials based on phosphorus‐containing polyhedral oligomeric silsesquioxane and bismaleimide/diallylbisphenol a with improved thermal resistance and dielectric properties

Polyhedral oligomeric silsesquioxane containing 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DP) was used to flame‐retard 4,4′‐bismaleimidophenyl methane (BDM)/2,2′‐dially bisphenol A (DBA) resins, and the integrated properties of the resins were investigated. The fire resistance of BDM/DBA resins containing DP was analyzed by limiting oxygen index (LOI) and vertical burning (UL94) tests. The results show that DP increased the LOI of the resins from 25.3 to 38.5%. The BDM/DBA resins were evaluated to have a UL‐94 V‐1 rating, which did not satisfy the high standards of industry. On the other hand, BDM/DBA containing DP achieved a UL‐94 V‐0 rating. The thermal stability and char formation were studied by thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy. TGA and scanning electron microscopy–energy‐dispersive X‐ray spectrometry measurements demonstrated that the DP resulted in an increase in the char yield and the formation of the thermally stable carbonaceous char. The results of Raman spectroscopy showed that the DP enhanced the graphitization degree of the resin during combustion. Moreover, the modified BDM/DBA resins exhibited improved dielectric properties. Specifically, the dielectric constant and loss at 1 MHz of the BDM/DBA/15% DP resin were 3.11 and 0.008, respectively, only about 93 and 73% of those of the BDM/DBA resin. All of the investigations showed that DP was an effective additive for developing high‐performance resins with attractive flame‐retardant and dielectric properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41545.     

Synthesis,flame‐retardancy testing,and preliminary mechanism studies of nonhalogenated aromatic boronic acids: A new class of condensed‐phase polymer flame‐retardant additives for acrylonitrile–butadiene–styrene and polycarbonate

This study describes the syntheses and thermal properties of aromatic boronic acids and their use as flame retardants. The possible flame‐retardancy mechanisms are also discussed. The materials were synthesized from aromatic bromides using one of two procedures. The first procedure involved traditional approaches to boronic acids, using lithium–halogen exchange and quenching with trimethylborate followed by hydrolysis. The second procedure used a nickel catalyst and a dialkoxy borane to generate aromatic dialkoxyboronates that were converted to boronic acids by acid hydrolysis. The thermal properties of these aromatic boronic acids were studied using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). These materials were blended into acrylonitrile–butadiene–styrene (ABS) and polycarbonate (PC) resins and tested for ignition resistance, using the UL‐94 flame test. A 10 wt % loading of 1,4‐benzenediboronic acid in polycarbonate gave a UL‐94 V‐0 result. This same diboronic acid showed flame retardancy and char formation in ABS, but this result was not quantifiable by the UL‐94 test. Burn times for the ABS samples often exceeded 5 min, thereby showing unusual resistance to consumption by fire. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1257–1268, 2000     

Flame retarded epoxy resins by adding layered silicate in combination with the conventional protection‐layer‐building flame retardants melamine borate and ammonium polyphosphate

The pyrolysis and flammability of phosphonium‐modified layered silicate epoxy resin nanocomposites (EP/LS) were evaluated when LS was combined with two flame retardants, melamine borate (MB) and ammonium polyphosphate (APP), that also act via a surface protection layer. Thermogravimetry (TG), TG coupled with Fourier Transform Spectroscopy (TG‐FTIR), oxygen index (LOI), UL 94 burning chamber (UL 94) and cone calorimeter were used. The glassy coating because of 10 wt % MB during combustion showed effects in the cone calorimeter test similar to nanodispersed LS, and somewhat better flame retardancy in flammability tests, such as LOI and UL 94. Adding APP to EP resulted in intumescent systems. The fire retardancy was particularly convincing when 15 wt % APP was used, especially for low external heat flux, and thus, also in flammability tests like LOI and UL 94. V0 classification is achieved when 15 wt % APP is used in EP. The flame retardancy efficiency of the protection layers formed does not increase linearly with the MB and APP concentrations used. The combination of LS with MB or APP shows antagonism; thus the performance of the combination of LS with MB or APP, respectively, was disappointing. No optimization of the carbonaceous‐inorganic surface layer occurred for LS‐MB. Combining LS with APP inhibited the intumescence, most probably through an increase in viscosity clearly above the value needed for intumescent behavior. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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     

Synthesis of a novel cross‐linked organophosphorus‐nitrogen containing polymer and its application in flame retardant epoxy resins

A novel cross‐linked organophosphorus–nitrogen polymetric flame retardant additive poly(urea tetramethylene phosphonium sulfate) defined as PUTMPS was synthesized by the condensation polymerization between urea and tetrahydroxymethyl phosphonium sulfate. Its chemical structure was well characterized by Fourier transform infrared (FTIR) spectroscopy, ¹³C and ³¹P solid‐state nuclear magnetic resonance. The synthesized PUTMPS and curing agent m‐phenylenediamine were blended into epoxy resins to prepare flame retardant epoxy resin thermosets. The effects of PUTMPS on fire retardancy and thermal degradation behavior of EP/PUTMPS thermosets were investigated by limiting oxygen index (LOI), vertical burning test (UL‐94), cone calorimeter measurement, and thermalgravimetric analysis (TGA) tests. The surface morphologies and chemical compositions of char residues for cured epoxy resins were investigated by scanning electron microscopy and X‐ray photoelectron spectroscopy (XPS), respectively. Water resistant properties of epoxy resin thermosets were evaluated by putting the samples into distilled water at 70°C for 168 h. The results demonstrated that the EP/12 wt% PUTMPS thermosets successfully passed UL‐94 V‐0 flammability rating and the LOI value reached 31.3%. The TGA results indicated that the incorporation of PUTMPS promoted epoxy resin matrix decomposed and char forming ahead of time, which led to a higher char yield and thermal stability for epoxy resin thermosets at high temperature. The morphological structures and analysis of XPS for the char residues of the epoxy resin thermosets shown that PUTMPS benefited to the formation of a sufficient, more compact, and homogeneous char layer with rich flame retardant elements on the materials surface during burning, which prevented the heat transmission and diffusion, limited the production of combustible gases, inhibited the emission of smoke, and then led to the reduction of the heat release rate and smoke produce rate. After water resistance tests, EP/12 wt% PUTMPS thermosets still remained excellent flame retardancy. Copyright © 2015 John Wiley & Sons, Ltd.     

Polyamide‐enhanced flame retardancy of ammonium polyphosphate on epoxy resin

An attractive intumescent flame retardant epoxy system was prepared from epoxy resin (diglycidyl ether of bisphenol A), low molecular weight polyamide (cure agent, LWPA), and ammonium polyphosphate (APP). The cured epoxy resin was served as carbonization agent as well as blowing agent itself in the intumescent flame retardant formulation. Flammability and thermal stability of the cured epoxy resins with different contents of APP and LWPA were investigated by limited oxygen index (LOI), UL‐94 test, and thermogravimetric analysis (TGA). The results of LOI and UL‐94 indicate that APP can improve the flame retardancy of LWPA‐cured epoxy resins. Only 5 wt % of APP can increase the LOI value of epoxy resins from 19.6 to 27.1, and improve the UL‐94 ratings, reaching V‐0 rating from no rating when the mass ratio of epoxy resin to LWPA is 100/40. It is much interesting that LOI values of flame retardant cured epoxy resins (FR‐CEP) increase with decreasing LWPA. The results of TGA, FTIR, and X‐ray photoelectron spectroscopy (XPS) indicate that the process of thermal degradation of FR‐CEP consists of two main stages: the first stage is that a phosphorus rich char is formed on the surface of the material under 500°C, and then a compact char yields over 500°C; the second stage is that the char residue layer can give more effective protection for the materials than the char formed at the first stage do. The flame retardant mechanism also has been discussed according to the results of TGA, FTIR, and XPS for FR‐CEP. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermal degradation and flame retardance of epoxy resins containing a microencapsulated flame retardant

Two steps were used in the synthesis of a microencapsulated intumescent flame retardant (MIFR). First bis (1‐oxo‐2,6,7‐trioxa‐l‐phosphabicyclo[2.2.2]octane‐4‐methylol) phosphate melaminium salt (Melabis) was synthesized. Then the Melabis was encapsulated with melamine resin to obtain the MIFR. Its structure was characterized by XPS, SEM, and elemental analysis, and the factors affecting microencapsulation were identified and discussed. Epoxy resins (EP) were modified with the MIFR to prepare flame‐retardant EP, whose flammability and burning behavior were characterized by UL 94 and limiting oxygen index (LOI) tests. The microcapsules (20% by weight) were added to EP in order to achieve an LOI of 29.5% and a UL 94 rating of V‐0. The thermal properties of epoxy resins containing the MIFR were investigated by thermogravimetry (TG) and differential thermogravimetry (DTG). The FR decreased by weight loss, R_max (the maximum weight loss rate), and the thermal stability of EP while promoting the formation of an effective charring layer. The char structures were studied by SEM. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers     

Click chemistry‐assisted preparation and properties of phosphorus and nitrogen synergistic flame retardant optical resin with a high refractive index

In this study, halogen‐free flame retardant tri(acryloyloxyethyl) phosphate (TAEP) was prepared using 2‐hydroxyethyl acrylate and phosphorus oxychloride. The chemical structure of TAEP was characterized by Fourier transform infrared and proton nuclear magnetic resonance spectrometers. The mixture of TAEP, acrylamide, and pentaerythritol tetrathioglycolate with different P, N, and S content were used to prepare flame retarding optical resin via the click chemistry curing. The curing performance, thermal stability, and flame retardant performance of the optical resins were measured by differential scanning calorimeter, thermogravimetric analyzer, vertical burning tester, and limiting oxygen index test, respectively. Additionally, the morphology of the burned residual was investigated by scanning electronic microscopy, and the refractive indices of the optical resins were measured by an Abbe Refractometer. The results strongly indicated that increasing sulfur content in resins improved their refractive indices, but deteriorated their flame retardancy. Meanwhile, the nitrogen element was helpful for the flame retardancy of the optical resin. With S N, and P contents of 3.00%, 1.00%, and 6.70 wt %, respectively, the refractive index of the optical resin reached up to 1.4987, and its flame retardancy achieved the UL‐94 V‐0 level and the LOI value of 29.3%. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46648.     

新型磷系阻燃剂四苯基(双酚-A)二磷酸酯阻燃PC/ABS的研究

利用自制的四苯基(双酚-A)二磷酸酯(BDP)及其复配体系制备了阻燃PC/ABS,研究了阻燃PC/ABS的力学性能、氧指数(LOI)和垂直燃烧测试性能(UL94)、材料的阻燃性能和烟气释放。结果表明:采用15%的BDP阻燃PC/ABS,材料的冲击强度下降了12.82%,LOI达到30.0%,UL94阻燃性能达到V—0级,平均热释放速率(av-HRR)和最大热释放速率(pk-HRR)分别下降了35.84%和31.17%,点燃时间(TTI)延长18s,火势增长指数(FGI)下降了46.72%,比消光面积(SEA)上升了6.68%;采用BDP/APP复配阻燃PC/ABS,材料的冲击强度最大降幅为33.33%,LOI最大可达30.1%,UL94阻燃性能由V—0级降为V—1级,av-HRR和pk-HRR最大分别下降40.89%和31.2%,TTI最大延长20s,FGI最大降幅为50.37%,SEA最大涨幅为11.14%;采用BDP/纳米SiO2复配阻燃PC/ABS,当纳米SiO2的添加量为7%时,材料的冲击强度上升了5.13%,LOI达到31.1%,UL94阻燃性能达到V—0级,av-HRR和pk-HRR分别下降了43.18%和4069%,TTI延长20s,FGI降幅为59.12%,平均比消光面积(av-SEA)涨幅为8.09%,6min内av-SEA下降6.92%,(6min总发烟指数)TSPI6min下降5.54%,阻燃、抑烟效果最佳,对PC/ABS材料的力学性能影响最小。     

Novel flame retardant thermosets from nitrogen‐containing and phosphorus‐containing epoxy resins cured with dicyandiamide

A novel phosphorus‐containing epoxy resin (EPN‐D) was prepared by addition reaction of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene 10‐oxide (DOPO) and epoxy phenol‐ formaldehyde novolac resin (EPN). The reaction was monitored by epoxide equivalent weight (EEW) titration, and its structure was confirmed by FTIR and NMR spectra. Halogen‐free epoxy resins containing EPN‐D resin and a nitrogen‐containing epoxy resin (XT resin) were cured with dicyandiamide (DICY) to give new halogen‐free epoxy thermosets. Thermal properties of these thermosets were studied by differential scanning calorimeter (DSC), dynamic mechanical analysis (DMA), thermal mechanical analyzer (TMA) and thermal‐gravimetric analysis (TGA). They exhibited very high glass transition temperatures (T_gs, 139–175°C from DSC, 138–155°C from TMA and 159–193°C from DMA), high thermal stability with T_{d,5 wt %} over 300°C when the weight ratio of XT/EPN‐D is ≥1. The flame‐retardancy of these thermosets was evaluated by limiting oxygen index (LOI) and UL‐94 vertical test. The thermosets containing isocyanurate and DOPO moieties showed high LOI (32.7–43.7) and could achieve UL‐94 V‐0/V‐1 grade. Isocyanurate and DOPO moieties had an obvious synergistic effect on the improvement of the flame retardancy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

The effect of red phosphorus on the fire properties of intumescent pine wood flour – LDPE composites

Red phosphorus (RP) was used to improve the fire performance of wood flour – low density polyethylene (LDPE) composites containing ammonium polyphosphate (APP). The fire performance of LDPE‐based composites was investigated by using limiting oxygen index (LOI), UL‐94 standard, thermogravimetric analysis, and cone calorimeter. The addition of 30 wt% APP increased the LOI value from 17.5 to 24.2 and still burned to clamp (BC) in UL‐94 test. The RP showed beneficial effect when combinedly used with APP. The maximum beneficial effect was seen at ratio of 5:1 (APP : RP) with the highest LOI value of 27.2 and UL‐94 rating of V0. RP showed its beneficial effect via increasing the gas phase action of the flame retardant system. Copyright © 2015 John Wiley & Sons, Ltd.     

磷氮复配无卤阻燃聚苯醚合金的研究

采用固体阻燃剂间苯二酚双[二(2,6-二甲苯基)磷酸酯](RXP)及其与三聚氰胺氰脲酸盐(MCA)的复配阻燃剂,制备了无卤阻燃聚苯醚/高抗冲聚苯乙烯/苯乙烯-丁二烯-苯乙烯热塑性弹性体(PPE/PS-HI/SBS)合金,通过氧指数、水平垂直燃烧、扫描电子显微镜、力学性能等测试分析方法,考察了PPE/PS-HL/SBS合...     

The application of organophosphorus flame‐retardants in epoxy resin

The influence of two novel aryl phosphate mixtures on fire retardancy and the thermal stability of epoxy resin were studied. Combustion behavior, decomposition pathway, and thermal and thermo‐oxidative degradation of the epoxy resin were examined by using the limiting oxygen index, vertical burning test (UL‐94), cone calorimeter test, thermogravimetric analysis, and thermogravimetry coupled with Fourier‐transform infrared spectroscopy. The morphology of the residues from the degradation of flame‐retarded epoxy resins was investigated by using scanning electron microscopy. Data from the cone calorimeter test demonstrated that the total heat evolved, heat release rate, and peak heat release rate decreased significantly when the epoxy resin contained these retardants. Moreover, a 20 wt% of both phosphate mixtures in the epoxy resin allowed for a satisfactory oxygen index (30–33%) and for UL‐94 V2 to be achieved. The condensed‐phase and gas‐phase actions of these aryl phosphate flame‐retardants are proposed as the mode of flame‐retardancy in epoxy resins. J. VINYL ADDIT. TECHNOL., 23:142–151, 2017. © 2015 Society of Plastics Engineers     

Synthesis of a novel phosphorus‐containing dicyclopentadiene novolac hardener and its cured epoxy resin with improved thermal stability and flame retardancy

A novel phosphorus‐containing dicyclopentadiene novolac (DCPD‐DOPO) curing agent for epoxy resins, was prepared from 9,10‐dihydro‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) and n‐butylated dicyclopentadiene phenolic resin (DCPD‐E). The chemical structure of the obtained DCPD‐DOPO was characterized with FTIR, ¹H NMR and ³¹P NMR, and its molecular weight was determined by gel permeation chromatography. The flame retardancy and thermal properties of diglycidyl ether bisphenol A (DGEBA) epoxy resin cured with DCPD‐DOPO or the mixture of DCPD‐DOPO and bisphenol A‐formaldehyde Novolac resin 720 (NPEH720) were studied by limiting oxygen index (LOI), UL 94 vertical test and cone calorimeter (CCT), and differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. It is found that the DCPD‐DOPO cured epoxy resin possess a LOI value of 31.6% and achieves the UL 94 V‐0 rating, while its glass transition temperature (T_g) is a bit lower (133 °C). The T_g of epoxy resin cured by the mixture of DCPD‐DOPO and NPEH720 increases to 137 °C or above, and the UL 94 V‐0 rating can still be maintained although the LOI decreases slightly. The CCT test results demonstrated that the peak heat release rate and total heat release of the epoxy resin cured by the mixture of DCPD‐DOPO and NPEH720 decrease significantly compared with the values of the epoxy resin cured by NPEH720. Moreover, the curing reaction kinetics of the epoxy resin cured by DCPD‐DOPO, NPEH720 or their mixture was studied by DSC. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44599.     

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.     

Combustion characteristics and synergistic effects of red phosphorus masterbatch with expandable graphite in the flame retardant HDPE/EVA composites

In this work, the flammability behaviors and synergistic effects of red phosphorus masterbatch (RPM) with expandable graphite (EG) in flame‐retardant high‐density polyethylene/ethylene vinyl‐acetate copolymer (HDPE/EVA) composites have been investigated by limiting oxygen index (LOI), UL‐94 test, cone calorimeter test (CCT), thermogravimetric analysis (TGA), Fourier‐transform infrared (FTIR) and scanning electron microscopy (SEM). The data obtained from LOI, UL‐94 test and CCT showed that suitable amount of RPM had synergistic effects with EG in the HDPE/EVA/EG/RPM composites. The addition of RPM greatly increased the LOI values by 3.4%, obtained UL‐94 V‐0 rating, decreased the heat release rates and total heat release, and prolongated the ignition time when 6.7 phr RPM substituted for EG in the HDPE/EVA/EG/RPM composites. The data from TGA and FTIR spectra also indicated the synergistic effects of RPM with EG considerably enhanced the thermal degradation temperatures. The morphological observations after UL‐94, CCT, and SEM images presented positive evidences that the synergistic effects took place for RPM with EG, and the flame‐retardant mechanism has been changed in flame‐retardant HDPE/EVA/EG/RPM composites. The formation of stable and compact charred residues promoted by RPM acted as effective heat barriers and thermal insulations, which improved the flame‐retardant performances and prevented the underlying polymer materials from burning. POLYM. ENG. SCI., 55:2884–2892, 2015. © 2015 Society of Plastics Engineers     

Effects of organopalygorskite on intumescent flame‐retarded polypropylene

The effect of organopalygorskite (OPGS) on an intumescent flame retardant (IFR) low‐density polypropylene (PP) has been investigated using the limited oxygen index (LOI), vertical burning test (UL‐94) and thermogravimetric analysis (TGA). The results of the LOI and UL‐94 tests indicate that the addition of OPGS substantially increases the LOI value for PP/IFR at a OPGS to IRF mass ratio of 2/28 with 30 wt% of total flame retardant. In addition, the samples pass the V‐0 rating in the UL‐94 tests. The results indicate that the addition of 2.0 wt% of OPGS simultaneously increases the tensile strength and bending strength of PP/IFR. J. VINYL ADDIT. TECHNOL., 24:281–287, 2018. © 2016 Society of Plastics Engineers     

Synergistic effects of 4A zeolite on the flame‐retardant properties and thermal stability of an efficient halogen‐free flame‐retardant EVA composite

The synergistic effects of 4A zeolite (4A) on the thermal degradation, flame retardancy, and char formation of an efficient halogen‐free flame‐retardant ethylene‐vinyl acetate copolymer composite (EVA/IFR) were investigated by limited oxygen index (LOI), vertical burning test (UL‐94), cone calorimeter test (CCT), digital photography, scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), laser Raman spectroscopy (LRS) and thermogravimetric analytical (TGA) methods. It was found that a small amount of 4A clearly improved the LOI value of the EVA/IFR composite and reinforced the fire retardant performance with a great reduction in the combustion parameters of the EVA/IFR system from the CCT test. The entire composites passed the UL‐94 V‐0 rating test. The TGA and integral procedure decomposition temperature (IDPT) results showed that 4A enhanced the thermal stability of the EVA/IFR system and increased the char residue content effectively. The morphological structures observed by digital and SEM imaging revealed that 4A could promote EVA/IFR to form a more continuous and compact intumescent char layer. The LRS and EDS results demonstrated that by introduction of 4A into the EVA/IFR system, a more graphite structure was formed with increase phosphorus content in the char residue. POLYM. ENG. SCI., 56:380–387, 2016. © 2016 Society of Plastics Engineers     

Melamine poly(metal phosphates) as flame retardant in epoxy resin: Performance,modes of action,and synergy

Melamine poly(metal phosphates) (MPMeP) are halogen‐free flame retardants commercialized under the brand name Safire. Melamine poly(aluminum phosphate) (MPAlP), melamine poly(zinc phosphate) (MPZnP), and melamine poly(magnesium phosphate) (MPMgP) were compared in an epoxy resin (EP). The thermal decomposition, flammability, burning behavior, and glass transition temperature were investigated using thermogravimetric analysis, pyrolysis combustion flow calorimeter, UL 94 testing, cone calorimeter, and differential scanning calorimetry. While the materials exhibited similarities in their pyrolysis, EP + MPZnP and EP + MPMgP showed better fire behavior than EP + MPAlP due to superior protective properties of the fire residues. Maintaining the 20 wt % loading, MPZnP was combined with various other flame retardants. A synergistic effect was evident for melamine polyphosphate (MPP), boehmite, and a derivative of 6H‐Dibenzo[c,e][1,2]oxaphosphinine‐6‐oxide. The best overall performance was observed for EP + (MPZnP + MPP) because of the best protection effectiveness of the fire residue. EP + (MPZnP + MPP) achieved V1/V0 in UL 94, and an 80% reduction in the peak heat release rate. This study evaluates the efficiency of MPMeP in EP, alone and in combination with other flame retardants. MPMeP is a suitable flame retardant for epoxy resin, depending on its kind and synergists. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43549.     

Novel synergistic flame‐retardant system of Mg–Al–Co–LDHs/DPCPB for ABS resins

Acrylonitrile‐butadiene‐styrene (ABS) resins are widely used in many sectors of the industry due to excellent mechanical properties, low temperature resistance, heat resistance, and chemical resistance. However, its flammability constitutes a key limitation in their applications. Consequently, development of flame‐retarding ABS resins is imperative. Herein, we report a novel synergistic system composed of Mg–Al–Co–layered double hydroxides (LDHs) prepared via a co‐precipitation method, and [4‐(diphenoxy‐phosphorylamino)‐6‐phenyl‐[l,3,5] triazin‐2‐y1]‐phosphoramidic acid diphenyl ester (DPCPB), a novel intumescent flame retardant. The properties of the as‐prepared LDHs/DPCPB/ABS composites are evaluated using standard combustion performance tests including limiting oxygen index (LOI) and vertical burning test (UL‐94). Novel ABS resins with the composition of ABS/DPCPB = 100/25 and ABS/DPCPB/LDHs = 100/2l/4 exhibit higher LOIs, 23.9 and 24.7, respectively, compared to 18.1 for the pure ABS. Meanwhile, they meet the V‐2 and A‐1 level, respectively, in UL‐94 tests. Moreover, the prepared composites exert flame‐retarding effects in gas phase and condensed phase simultaneously. Our results reveal synergistic effects between Mg–Al–Co–LDHs and DPCPB for the flame retardation of ABS resins. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46319.