Search

Severe flame retardancy and poor impact resistance of epoxy resins (EPs) have become key factors limiting their industrial application. Herein, a strategy is developed to integrate nitrogen‐rich black phosphorus (BP) loaded with cerium oxide via aryl diazonium chemistry to reduce the flame risk of the EPs. Cone test results exhibit that the fire hazard of EPs containing 2 wt.% BP‐NHH‐Ce is suppressed effectively, such as that total heat release rate (THR) is reduced by 46.9%, the peak heat release rate (pHRR) is reduced by 56.2%, and the total smoke production (TSP) is reduced by 48.9%. With only 1.0 wt.% of the BP‐NHH‐Ce added, the nanocomposite can reach up to 30.5 of LOI value and simultaneously upgrade the UL‐94 rate to V‐0. In addition, the nano‐structure is beneficial to stress transfer and homogenization, which leads to significant elevation (28.2%) for the impact strength of EPs. This developed new EP/BP‐NHH‐Ce nanocomposite merits the high‐end field application of EPs. [ABSTRACT FROM AUTHOR]

A systematic series of flexible polyurethane foams (FPUF) with different concentrations of flame retardants, bis([dimethoxyphosphoryl]methyl) phenyl phosphate (BDMPP), and melamine (MA) or expandable graphite (EG) was prepared. The mechanical properties of the FPUFs were evaluated by a universal testing machine. The pyrolysis behaviors and the evolved gas analysis were done by thermogravimetric analysis (TGA) and TGA coupled with Fourier‐transform infrared (TG‐FTIR), respectively. The fire behaviors were studied by limiting oxygen index (LOI), UL 94 test for horizontal burning of cellular materials (UL 94 HBF), and cone calorimeter measurement. Scanning electronic microscopy (SEM) was used to examine the cellular structure's morphology and the postfire char residue of the FPUFs. LOI and UL 94 HBF tests of all the flame retarded samples show improved flame retardancy. BDMPP plays an essential role in the gas phase because it significantly reduces the effective heat of combustion (EHC). This study highlights the synergistic effect caused by the combination of BDMPP and EG. The measured char yield from TGA is greater than the sum of individual effects. No dripping phenomenon occurs during burning for FPUF‐BDMPP‐EGs, as demonstrated by the result of the UL 94 HBF test. EG performs excellently on smoke suppression during burning, as evident in the result of the cone calorimeter test. MA reduces the peak heat release rate (pHRR) significantly. The synergistic effect of the combination of BDMPP and EG as well as MA offers an approach to enhance flame retardancy and smoke suppression. [ABSTRACT FROM AUTHOR]

Flexible polyurethane foam (FPUF) is extremely flammable and will release a large number of toxic fumes during the combustion process, which brings great safety hazards. Therefore, a binary hybrid nanocoating composed of graphene oxide (GO) and octaamino polyhedral oligomeric silsesquioxane (OA‐POSS) is deposited on the surface of FPUF through layer‐by‐layer self‐assembly technology, with the aim of enhance the flame retardancy and smoke suppression properties of the hybrid FPUF. Compared with pure FPUF, the peak heat release rate, the total heat release, the peak smoke production rate and the total smoke release of FPUF@GO/OA‐POSS‐6 is decreased by 67.3%, 28.3%, 65.03% and 42.9%, indicating the hybrid FPUF excellent flame retardancy and smoke suppression properties. Compared with pure FPUF, the tensile strength of FPUF@GO/OA‐POSS‐6 is increased by 42%, and after three times of compression, the compressive strength increases by 83.17% on average. Facts have proved that the hybrid effect between GO and OA‐POSS enhances the flame retardancy, smoke suppressive effects, tensile strength and compressive strength of FPUF. [ABSTRACT FROM AUTHOR]

Flexible polyurethane foam (FPUF), a widely used cushioning and comfort component for homeware and automobile industries if tailored for flame resistance, can exhibit enhanced market value. With the view to preparing such protective films, multilayered coating composed of montmorillonite (MMT) and triphenyl phosphate (tPP) along with polyethyleneimine (PEI), poly[(o‐cresyl glycidyl ether)‐co‐formaldehyde] (CNER), tPP solution and MMT suspension was deposited via layer‐by‐layer technique so as to suppress the flammability of FPUF. A comparative study applying "cone test" revealed that multilayered coatings having PEI(CNER/NH2‐MMT/PEI)n and PEI(CNER/NH2−MMT/tPP)n architectures, where "n" signifies the number of layer pairs, exhibited remarkable decrease in "peak heat release rate" (pHRR) of 20 and 25%, respectively, as compared to uncoated FPUF. Moreover, these coatings showed a 50% reduction in "fire growth rate index" (FIGRA) when compared to uncoated FPUF. This significant decrease in FIGRA after a specific combination of epoxy‐clay features that such multilayered coatings can be used to protect the underlying FPUF due to the labyrinth effect offered by MMT and accelerated char formation by tPP. Furthermore, the evolution of volatile gases upon combustion of multilayered coated foam decreased due to the inhibition of oxygen permeation owing to the protective effect of the coating. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48890. [ABSTRACT FROM AUTHOR]

Summary: Induced by extremely inflammable characteristic, fire accidents worldwide of crops frequently occur and give rise to loss of life and personal injury. Given this problem, combustion behavior characterization of four major crops was investigated by cone calorimeter. Results confirmed the less quantity of crops needed longer time to be ignited. Meanwhile, the linear relation between the inverse square of time to ignition and heat flux of crops was found. For heat release rate (HRR), it was demonstrated that more quantity of crops prolonged the heat release process. For instance, with heat flux of 50 kW/m2, HRR values of 100 and 50 g soybean at 400 seconds were 212 and 40 kW/m2. Besides, peak values of HRR (PHRR) were close with different mass, especially for corn. Interestingly, compared to less quantity, more quantity crops were harder to be ignited at same heat flux. In addition to soybean, PHRR and total heat release (THR) of crops was gradually increased with the increasing heat flux. Meanwhile, THR values of 100 g crops were lower than double THR of 50 g crops. The investigation of combustion behavior characteristic could guide the safety storage of crops, thus avoiding the occurrence of crops fire hazards. [ABSTRACT FROM AUTHOR]

In the present work, lanthanum phenylphosphonate (LaPP)–based multilayered film was fabricated on the surface of flexible polyurethane (PU) foam by layer‐by‐layer self‐assembled method. The successful deposition of the coating was confirmed by scanning electron microscopy (SEM) and energy‐dispersive X‐ray (EDX). Subsequently, the thermal decomposition and burning behavior of untreated and treated PU foams were investigated by thermogravimetric analysis (TGA) and cone calorimeter, respectively. The TGA results indicated that Tmax2 of treated PU foams were increased by approximately 15°C to 20°C as compared with untreated PU foam. The peak heat release rate (PHRR) and total heat release (THR) of PU‐6 (with 19.5 wt% weight gain) were 188 kW/m2 and 20.3 MJ/m2, with reductions of 70% and 15% as compared with those of untreated PU foam, respectively. Meanwhile, the smoke production of treated PU foam was suppressed after the construction of LaPP‐based coating. [ABSTRACT FROM AUTHOR]

In this study, high electrical conductivity and flame retardant electrothermal ethylene‐vinyl acetate (EVA) films were fabricated by using carbon nanotubes‐wrapped ammonium polyphosphate (CAPP) and conductive carbon black (CCB). CAPP was used as a synergistic conductive filler and flame retardant to improve the electrical conductivity and fire safety of the electrothermal film at the same time. Besides, the heat release rate (HRR) and the total heat release (THR) of EVA‐5 decreased about 81.5% and 57.3% compared with those of pure EVA film, respectively. Moreover, by incorporating a small amount of CAPP, EVA‐5 can reach up to V‐0 rating with an limiting oxygen index (LOI) value of 31%. EVA film fabricated by CCB and CAPP as conductive material exhibited almost 10 times increment on electrical conductivity than that of same content for CCB alone. And time vs temperature profiles of EVA‐5 showed a stable trend over 3600 seconds without any offset at a given applied voltage of 15 V. Moreover, its excellent cycle heating performance indicated that the electrothermal film can be recycled, which meets the requirements of sustainable development. In a word, this novel strategy provides a simple and effective way to obtain a high conductive and fire safety electrothermal film. [ABSTRACT FROM AUTHOR]

Graphene‐polyaniline/nickel hydroxide ternary hybrid (RGO‐PANI/Ni(OH)2) was synthesized and incorporated into epoxy resin (EP) to improve the fire retardant property. Thermogravimetric analysis results showed that the RGO‐PANI/Ni(OH)2 nanohybrid could catalyze the thermal degradation of epoxy matrix that was essential to trigger the char formation. The char yield of the RGO‐PANI/Ni(OH)2/EP composite was improved compared with that of the samples with graphene and polyaniline only. With 3.0‐wt% RGO‐PANI/Ni(OH)2, significant reduction in peak heat release rate (40%) and peak smoke production rate (36%) was observed in the cone calorimeter tests. Thermogravimetric analysis/infrared spectrometry (TG‐IR) results indicated that the flammable volatiles of the RGO‐PANI/Ni(OH)2/EP composite was reduced compared with those of the EP and RGO‐PANI/EP. The superior flame retardant and smoke suppressant behaviors of the RGO‐PANI/Ni(OH)2 nanohybrid over RGO‐PANI were attributed to the combination of good barrier effect of graphene with catalytic ability of char formation of PANI and metal hydroxide. [ABSTRACT FROM AUTHOR]

A novel and highly effective flame retardant (FR), DOPO‐TPMP oligomer, was synthesized by a simple condensation of 4‐(hydroxymethyl)‐2,6,7‐trioxa‐1‐phosphabicyclo[2.2.2]octane‐1‐oxide and phosphorus oxychloride followed by a polycondensation reaction with 6‐(2,5‐dihydroxyphenyl)‐6H‐dibenzo[c,e][1,2]oxaphosphinine‐6‐oxide. The chemical structure of DOPO‐TPMP was well characterized using Fourier transform infrared and NMR spectra. DOPO‐TPMP was used as an additive‐type FR for epoxy resin (EP). The FR properties of the resultant EP composites were investigated by limiting oxygen index (LOI) test, UL‐94 vertical burning test and cone calorimeter measurements. Specifically, the EP composite containing 10.0% DOPO‐TPMP achieved a LOI value of 36.1%, V‐0 rating in the UL‐94 test and a 58% reduction in peak heat release rate. Further mechanism analysis attributed the enhanced flame retardancy to the increased char yield on the addition of DOPO‐TPMP. © 2019 Society of Chemical Industry A novel oligomeric flame retardant, DOPO‐TPMP, was synthesized, which imparted high flame‐retardant performance to epoxy resins. [ABSTRACT FROM AUTHOR]

This work reported a facile fabrication method to modify molybdenum disulfide (MoS2) nanosheets with common flame retardant melamine phosphate (MAP) and then were incorporated into poly(butylene succinate) by melt blending method with the purpose of improving the thermal and flame retardancy properties. MAP modified MoS2 nanosheets dispersed well in poly(butylene succinate) composites with intercalated structure. The incorporation of MAP modified MoS2 nanosheets led to an increase of thermal degradation temperature and char formation as well as reduction of the peak heat release rate. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The pyrolysis process of polypropylene (PP), PP-based nanoclay composites, acrylonitrile-butadiene-styrene (ABS), and ABS/metal hydroxide nanorods (MHR)/grapheme nanosheets (GNS) composites in a cone calorimeter test was simulated with a recently developed numerical codes, the Federal Aviation Administration ThermaKin. First, the heat release rate (HRR) and the surface temperature as a function of time were compared with experiment data. With reasonable input parameters, the pyrolysis behaviors were predicted reasonably. Subsequently, the influence of the properties of char residue on the HRR was discussed. The char residue of PP/nanoclay acted as a heat transfer barrier, while the char layer of ABS/MHR/GNS acted as a mass transfer barrier. Finally, the sensitivity of the residue characteristic parameters to the model output was discussed. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

For improving the flame retardancy of epoxy resin (EP), β‐cyclodextrin@ ferrocene@hollow mesoporous silica microspheres (β‐CD@FE@HMS) were prepared successfully by the self‐assembly method. Then, they were used as flame retardant to improve the fire safety of EP. EP/β‐CD@FE and EP/HMS composites were also prepared for comparative study. The results showed that β‐CD@FE@HMS could effectively improve the thermal stability of EP, in which the initial degradation temperature and the amount of char residue of EP were increased. The content of small molecule toxic gases produced by the combustion of EP composite was also reduced apparently. With the addition of 5 wt% β‐CD@FE@HMS, LOI value of EP was increased to 27.5% from 19.8%, and UL‐94 reached V‐1 rating. Comparing with pure EP, the peak heat release rate and total heat release values of EP were reduced by 11.0% and 12.3%, respectively, and the total smoke production was reduced by 30.6%. EP/β‐CD@FE@HMS composite formed a higher quality char layer. Therefore, β‐CD@FE@HMS microspheres could improve the fire safety of EP. [ABSTRACT FROM AUTHOR]