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     

Inorganic/organic phosphorus-based flame retardants synergistic flame retardant rigid polyurethane foam

The flame-retardant rigid polyurethane foam (RPUF) composites are fabricated by ammonium polyphosphate (APP) with pentaerythritol phosphate (PEPA), phenoxycycloposphazene (PCP), and aluminum diethylphosphinate (ADP), respectively, which are labeled as RPUF-1, RPUF-2, and RPUF-3. The influence of flame retardants on the apparent density and compressive strength of RPUF is studied. The results reveal that flame retardants not only improve the apparent density, but also improve the compressive strength of RPUF composites. The limiting oxygen index (LOI) results reveal that these inorganic/organic phosphorus-based flame retardants improve the LOI significantly, especially for RPUF-2 and RPUF-3 systems. The cone calorimeter test results suggest that the peak of heat release of RPUF-1, RPUF-2, and RPUF-3 systems decrease by 38%, 41%, and 52% likened to that of pure RPUF. And APP and ADP system performs best in declining the heat release. And APP and PEPA systems perform best in decreasing the smoke release. The flame retardancy mechanism of RPUF composites is analyzed in details.     

Condensed‐phase flame retardation in nylon 6‐layered silicate nanocomposites: Films,fibers, and fabrics

Flame‐retardant properties of nylon 6/organically modified montmorillonite (OMMT) thin films, fibers, and fabrics were investigated to determine the efficacy of condensed‐phase flame‐retardant mechanism in relation to montmorillonite concentration, sample geometry, and flame test conditions. Horizontal flame spread conducted on thin films revealed no significant difference in burning behavior between nylon 6 and nanocomposites with 5 wt% OMMT. However, with a higher concentration level of 8–10 wt% OMMT, the films burned without any dripping. The flame spread rate was reduced by 30–40% as compared with nylon 6 films. Cone calorimeter study on nanocomposite films showed that the peak heat release rate of nylon 6 was reduced by 65–67% with 8–10 wt% OMMT. Undrawn nanocomposite monofilaments with 10 wt% OMMT burned slowly and steadily in Bunsen flame without dripping. In cone calorimeter, nanocomposite fabrics with 8 wt% OMMT showed reduced heat release rate and mass loss rate compared to nylon 6 fabrics with increase in fabric tightness factor. The mass loss rate was about 40–60% less when compared with nylon 6 fabrics. The fabric char structure remained intact after burning. This demonstrated the interdependence of fabric tightness factor, OMMT concentration, and source of heat flux in forming a protective char and affecting the flammability of fabrics. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Mechanical,thermal and combustion properties of intumescent flame retardant biodegradable poly (lactic acid) composites

ABSTRACT

Despite extraordinary mechanical properties and excellent biodegradability, poly (lactic acid) (PLA) still suffers from a highly inherent flammability, restricting its applications in the electric and automobile fields. Although a wide range of flame retardants have been developed to reduce the flammability, they normally compromise the mechanical strength of PLA. In this study, a series of composites based on PLA, have been prepared by melt-blending with intumescent flame retardants (IFRs). The morphology, thermal stability and burning behaviour of the composites were investigated using a scanning electron microscope–energy dispersive spectrometer (SEM–EDS), thermogravimetric analysis (TGA), the limiting oxygen index (LOI), vertical burning (UL-94) and the cone calorimeter test (CCT). The LOI value reached 38.5% and UL-94 could pass V-0 for the PLA/IFR composite containing only 12 wt-% IFR. The dispersion of IFR in PLA was observed using SEM–EDS. A significant improvement in fire retardant performance was observed for the PLA/IFR composite from the CCT (reducing the heat release rate and the total heat release). More importantly, compared to pure PLA, the addition of IFR did not seriously deteriorate the mechanical properties of the material.     

Combustion characteristics of cellulosic loose fibres

The aim of this paper is to study the combustion characteristics of loose fibrous cellulosic compounds through cone calorimeter measurements. The challenge in studying loose fibrous materials by cone calorimeter in a reproducible manner is met by optimizing various process parameters such as sample weight, heat flux and grid type. The method is validated using cotton fibres and fabrics with a range of flame retardant properties. Good correlations are obtained between the flame retardant content of samples and the heat release parameters for both the fibres and the fabrics. In addition, fibres from specific cotton cultivars showed statistically significant differences in heat release characteristics. This shows that valuable data concerning the combustion behaviour and the corresponding kinetics of loose fibrous compounds can be successfully gathered using a cone calorimeter. Thus, such data can be exploited to well define future fibre breeding programmes or fibre modification research. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis and characterization of bio-based intumescent flame retardant and its application in polyurethane

A novel bio-based P-N containing intumescent flame retardant melamine starch phytate (PSTM) was prepared via the reaction of phytic acid starch ester with melamine and characterized by Fourier transform infrared, scanning electron microscopy and thermogravimetric analysis (TGA). The effects of PSTM on thermal properties and flammability of rigid polyurethane (PU) foams were analyzed by TGA, limit oxygen index (LOI), vertical burning tests (UL-94) and cone calorimeter measurement. The TGA results demonstrated that the thermal stabilities of PU/PSTM foam at high temperature was enhanced with the increasing additive amount of PSTM. The results showed that PU foam with 30 php PSTM (PU/PSTM-30%) observed an LOI value of 25.9 and a UL-94 rating of V-0. Cone calorimetry data showed that peak heat release rate, total heat release and smoke production rate of PU/PSTM-30% were distinctly lower than that of pure PU. Further experimental results demonstrated that PSTM promotes well charring of PU which could protect the foam from combustion. This work developed a novel bio-based intumescent flame retardant by suing phytic acid and starch as the acid source and carbon source, respectively, which is of great significance to the preparation of environmental-friendly flame retardants.     

用锥形量热仪研究聚氨酯泡沫的阻燃性能

在50 kW/m2辐射功率下,利用锥形量热仪研究了氢氧化铝、卤系阻燃剂、氮系阻燃剂和磷系阻燃剂阻燃聚氨酯泡沫(PUF)的阻燃特性,获得了点燃时间、最大热释放速率、总热释放、比消光面积及质量损失速度等参数。结果表明,将热释放速率、燃烧总释放热和烟气释放量作为材料阻燃性能好坏的评价指标,阻燃剂聚磷酸铵（APP）和三聚氰胺磷酸盐（MP）是PUF的理想阻燃剂。     

Effect of flame heat flux on thermal response and fire properties of char‐forming composite materials

This study evaluates the effect of flame heat flux on the prediction of thermal response and fire properties of a char‐forming composite material. A simplified two‐layer flame model was developed and incorporated into a heat transfer thermal model to predict the thermal response and fire reaction characteristics of a burning material. A typical char‐forming material, E‐glass reinforced polyester composite, was used in the study. A cone calorimeter was used to measure the fire reaction characteristics of the composite. The flame heat flux in a cone calorimeter test setup was estimated using the simplified flame model. Thermal response and fire property predictions with and without the effect of flame heat flux were compared with experimental data obtained from the cone calorimeter tests. Results showed that the average flame heat flux of the composite in a cone calorimeter was 19.1 ± 6 kW/m² from model predictions. The flame had a significant effect on the thermal response and fire properties of the composite around the first heat release peak but the effect decreased rapidly afterwards. Copyright © 2012 John Wiley & Sons, Ltd.     

六苯氧基环三磷腈对PC/ABS合金的阻燃作用

通过极限氧指数测定(LOI)、垂直燃烧试验和锥型量热分析研究了六苯氧基环三磷腈(HPTCP)对聚碳酸酯/丙烯腈-苯乙烯-丁二烯共聚物(PC/ABS)合金的阻燃作用。结果表明:HPTCP对PC/ABS具有良好的阻燃效果。当添加量为15%时,阻燃PC/ABS的LOI为25.0%,阻燃等级达FV-0,并且与未阻燃PC/ABS相比,燃烧时的热释放速率、总热释放量、最高热释放速率、平均热释放速率,平均有效燃烧热和质量损失明显降低;热重分析表明,HPTCP对PC/ABS合金的热稳定性影响较小。热重和残余物分析结果表明,HPTCP主要是通过凝聚相产生阻燃作用,HPTCP的添加可有效抑制PC/ABS的分解,促进它成炭,形成膨胀性炭层,该炭层通过隔热、隔氧及阻止PC/ABS分解产物的挥发而产生阻燃作用。     

Epoxy resin/phosphorus‐based microcapsules: Their synergistic effect on flame retardation properties of high‐density polyethylene/graphene nanoplatelets composites

Two types of microcapsule flame retardants are prepared by coating ammonium polyphosphate (APP) and aluminum diethylphosphinate (ADP) with epoxy resin (EP) as the shell via in situ polymerization, and blended with high density polyethylene (HDPE)/graphene nanoplatelets (GNPs) composites to obtain flame‐retardant HDPE materials. Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), and water contact angle results confirm the formation of core–shell structures of EP@APP and EP@ADP. The limiting oxygen index (LOI), vertical burning test (UL‐94), cone calorimetry, and Raman spectroscopy are employed to characterize the HDPE/GNPs composites filled with EP@APP and EP@ADP core–shell materials. A UL94 V‐0 level and LOI of 34% is achieved, and the two flame retardants incorporated in the HDPE/GNPs composite at 20 wt % in total play a synergistic effect in the flame retardancy of the composite at a mass ratio of EP@ADP:EP@APP = 2:1. According to the cone‐calorimetric data, the compounding composites present much lower peak heat release rate (300 kW/m²) and total heat release (99.4 MJ/m²) than those of pure HDPE. Raman spectroscopic analysis of the composites after combustion reveals that the degree of graphitization of the residual char can reach 2.31, indicating the remarkable flame retarding property of the composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46662.     

Calorimetric study of flammable fabrics. II. Analysis of flame retardant-treated cotton

Efficiencies of three flame retardants for cellulose, phosphoric acid, diammonium phosphate, and THPOH ammonia finish, have been evaluated based on the heat release value and the rate of heat release of treated fabrics burning in air measured with the isoperibol calorimeter. The results were compared and correlated with those obtained previously with the bomb-calorimetric technique. Complete heat balances were obtained for the systems studied by correlation of the calorimetric data and the measurement of combustible gases evolved from the fabric burning in air. The rate of heat release was found to correlate with the flame propagation rate measured at a 45° angle. The results from the heat, rate, and combustible gas measurements were interpretable in terms of existing mechanisms of flame-retardant action.     

聚氨酯/乙烯-乙酸乙烯酯聚合物弹性体耐磨性及微观分析

为了探究聚合物弹性体耐磨性及微观形态,本文以沙柳液化产物与MDI反应生成聚氨酯为预聚体,EVA/PU进行接枝共聚形成聚合物弹性体,并利用扫面电镜探针显微镜等对聚合物弹性体进行了测试分析。结果表明:当含EVA为10%时材料的硬度达到最大,磨耗率也是最低的,分子的结晶度增大,两相的相容性也达到最佳状态。对EVA/PU弹性共体拉伸断裂面的扫面分析,发现随着EVA的加入量的增大,断面呈现由脆性断裂向韧性断裂过渡,并且在断裂的微观区出现了明显塑性变形。在扫描探针显微图下可以看到EVA/PU之间发生的接枝共聚现象,分子变小,同时分子的高度增加。这就说明EVAL中的游离羟基与PU预聚体发生了接枝反应。     

Fire retardancy of polypropylene composites reinforced with rice husks: From oxygen index measurements and cone calorimetry to large‐scale single‐burning‐item tests

Rice husks containing 12 wt % inorganic silica were incorporated together with halogen‐free fire retardants in a polypropylene matrix and extruded into facade profiles. An increase in the amount of rice husks resulted in an increase in the oxygen index. The cone calorimetry measurements showed that all of the fire retardants tested significantly reduced the peak heat‐release rate (pHRR) and maximum average rate of heat emission (MARHE) of the formulations and moderately reduced total heat release. The best results in terms of MARHE were achieved for the formulation including 24% melamine‐coated ammonium polyphosphate. pHRR and MARHE were reduced with increasing amount of rice husks. Single‐burning‐item (SBI) tests were performed for the extruded profiles based on rice husks and, for comparison, wood flour. In the best case, a B‐s2, d0 classification was obtained. The results obtained from cone calorimetry and SBI tests were in agreement. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46654.     

Butyltriphenylphosphine-based chelate borates influenced on flame retardancy of polystyrene composite containing self-expanded intumescent flame retardants

The polystyrene (PS) composite containing self-expanded intumescent flame retardant (polyphosphate ammonium and expandable graphite) was blended with three butyltriphenylphosphine-based chelate borates, respectively, to evaluate their effect on flame retardancy. The chemical structure of as-prepared three chelate borates was confirmed by nuclear magnetic resonance (NMR) and Fourier transform infrared spectrum (FTIR). The flame retardancy of various PS composites was evaluated by vertical burning test (UL-94), limited oxygen index (LOI), and cone calorimeter (CC). Flammability and combustion results suggested that one of chelate borates, named [BTP][BMB], made PS composite (PS4) obtain V-0 rating, 27.0 ± 0.3% LOI value, and reduction on heat release and smoke production with 17 wt% total flame retardants loading. The combustion residue was analyzed by scanning electron microscope and FTIR, and the pyrolysis gaseous products were investigated by TG-FTIR technique. Besides, complex viscosity of PS composites composed of various chelate borates from a rheology instrument indicated that the improvements of flame retardancy of PS composites depended on the temperature of construction of crosslinked network by expandable graphite, which the chelate borates showed distinctive influence. Accordingly, the flame-retarding mechanism about fast response to flame has been proposed.     

聚氨酯／蒙脱土复合阻燃硬质泡沫材料的研究

采用原位聚合法制备了蒙脱土阻燃硬质聚氨酯泡沫材料,并用多种添加型阻燃剂制备了阻燃聚氨酯硬质泡沫,同时尝试有机改性蒙脱土与添加型阻燃剂并用对聚氨酯硬质泡沫进行阻燃。用锥形量热仪测试了阻燃聚氨酯泡沫材料的燃烧性能,结果发现,材料的热释放速率、质量损失速率与纯聚氨酯硬质泡沫相比均显著降低,峰值热释放速率最多降低到纯硬质泡沫的55％,表明制备的泡沫材料具有较好的阻燃性。用X-射线衍射和扫描电镜分析了蒙脱土及有机改性蒙脱土的微观结构。通过分析材料的燃烧性能和燃烧残余物,探讨了其可能的阻燃机理。     

溴锑阻燃体系对PS-HI／有机蒙脱土复合材料的阻燃性研究

采用熔融法制备包括溴锑阻燃剂（TBBPA—Sb2O3）和有机蒙脱土（OMMT）并用体系的阻燃PS-HI复合材料；利用琏于耗氧原理的锥形量热仪测试并分析复合材料的燃烧性能，用扫描电子显微镜表征复合材料的微观结构肜貌，结果表明：TBBPA-Sb2O3与OMMT并用阻燃的PS-HI复合材料热释放速率、峰值热释放速率、平均热释放速率以技中烟速率均明显降低，火灾性能指数明显增加；形成的PS-HI／OMMT复合材料与TBBPA—Sb2O3体系之间具有阻燃协同效应，当TBPA—Sb2O3添加7．5份和2．5份，OMMT添加5份时，三者之间的阻燃协同作用最佳。     

Effect of charring agent THEIC on flame retardant properties of polypropylene

Tris(2‐hydroxyethyl) isocyanurate (THEIC) was used as charring agent and combined with ammonium polyphosphate (APP) to form an intumescent flame retardant (IFR) for polypropylene (PP). The flame retardancy and combustion performance of PP/IFR composite was tested by limiting oxygen index (LOI), UL‐94 vertical burning test and cone calorimeter. The results showed that PP/IFR composite had highest LOI of 34.8 and obtained V‐0 rating when 30 wt % IFR was loaded and mass ratio APP/THEIC was 2 : 1. The peak heat release (PHRR) and total heat release (THR) values of PP composite containing FRs were remarkably reduced compared with that of pure PP. However, water resistant test demonstrated the PP/IFR composite had poor flame retardant durability, both the LOI value and UL‐94 V‐rating decreased when PP/IFR composite was soaked in water at 70°C after 36 h. The degradation process and the char morphology of IFR and PP/IFR composite were investigated by TGA and SEM images. The possible reaction path between APP and THEIC in the swollen process was proposed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41214.     

“三源一体”壳核型阻燃剂的制备及其在聚乳酸中的应用

以聚磷酸铵（APP）为核,壳聚糖（CS）、氯化铁和埃洛石（HNT）为壳,以水为溶剂,通过自组装的方式制备了“三源一体”壳核型阻燃剂（APP@CS@HNT和APP@CS-Fe@HNT,分别简写为ACH和ACFH）,并将其用于提升聚乳酸（PLA）的阻燃性能。通过扫描电子显微镜、热重分析仪等对ACH和ACFH的组成及结构进行了分析,然后对PLA的阻燃性能进行表征。结果表明,PLA/15%ACFH（质量分数,下同）的阻燃性能优于纯PLA和PLA/15%ACH,PLA/15%ACFH的极限氧指数（LOI）最高,提升到29.5%,且UL 94达到V-0级;相较于纯PLA,PLA/15%ACFH的最大热释放速率（PHRR）和总热释放量（THR）分别下降了33.5%和22.0%,残炭量提高了12.5%;ACFH主要发挥凝聚相阻燃效果,燃烧过程能促进PLA基体形成大量连续、致密的炭层,起到抑制氧气和热量扩散的阻隔作用。     

磷-胺-醛树脂型阻燃剂处理落叶松的热分析及其动力学

将落叶松用一系列磷-胺-醛树脂型阻燃剂进行阻燃处理,所得阻燃落叶松采用热分析、锥形量热研究其热解行为,用氧指数、剩炭率、热释放速率、总热释放量等参数表征它的阻燃性能,并用Broido方程计算落叶松的动力学参数. 结果发现,阻燃落叶松氧指数、剩炭率增加,热释放速率、总热释放量降低,表明经阻燃剂处理的落叶松燃烧性降低. 落叶松经阻燃剂处理后,热解活化能降低很多,表明阻燃剂对落叶松热解具有催化作用,其主要热解阶段在低于300℃进行. 在此温度下,落叶松热解主要发生脱水、重排交联炭化反应,产生水、CO及CO2、固体残渣,可燃性气体大大降低,达到降低落叶松燃烧性的目的.     

MPP/PER/APP阻燃PP的阻燃及热裂解行为

采用聚磷酸蜜胺(MPP)／季戊四醇(PER)／聚磷酸铵(APP)三元膨胀型阻燃剂(IFR)阻燃聚丙烯(PP),测定了阻燃PP的极限氧指数(LOI)、UL94V阻燃性及热稳定性,以傅里叶变换红外光谱(FTIR)分析了阻燃PP的热分解残余物。以锥形量热仪(CONE)测定了阻燃PP的诸多与火灾有关的阻燃参数,包括释热速度、质量损失速度、总释热量、有效燃烧热、比消光面积及引燃时间等,以光电子能谱(XPS)测定了阻燃PP残炭表面的元素组成及XPS曲线拟合数据,还以扫描电镜(SEM)观测了阻燃PP残炭的形态。